Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

Users Online : 63353

AbstractMaterial and MethodsResultsDiscussionConclusionReferencesDOI and Others
Article in PDF How to Cite Citation Manager Readers' Comments (0) Audio Visual Article Statistics Link to PUBMED Print this Article Send to a Friend
Advertisers Access Statistics Resources

Dr Mohan Z Mani

"Thank you very much for having published my article in record time.I would like to compliment you and your entire staff for your promptness, courtesy, and willingness to be customer friendly, which is quite unusual.I was given your reference by a colleague in pathology,and was able to directly phone your editorial office for clarifications.I would particularly like to thank the publication managers and the Assistant Editor who were following up my article. I would also like to thank you for adjusting the money I paid initially into payment for my modified article,and refunding the balance.
I wish all success to your journal and look forward to sending you any suitable similar article in future"



Dr Mohan Z Mani,
Professor & Head,
Department of Dermatolgy,
Believers Church Medical College,
Thiruvalla, Kerala
On Sep 2018




Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."



Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018




Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."



Dr Kalyani R
Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018




Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
‘Knowledge is treasure of a wise man.’ The free access of this journal provides an immense scope of learning for the both the old and the young in field of medicine and dentistry as well. The multidisciplinary nature of the journal makes it a better platform to absorb all that is being researched and developed. The publication process is systematic and professional. Online submission, publication and peer reviewing makes it a user-friendly journal.
As an experienced dentist and an academician, I proudly recommend this journal to the dental fraternity as a good quality open access platform for rapid communication of their cutting-edge research progress and discovery.
I wish JCDR a great success and I hope that journal will soar higher with the passing time."



Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
Lucknow
On Sep 2018




Dr. Arunava Biswas

"My sincere attachment with JCDR as an author as well as reviewer is a learning experience . Their systematic approach in publication of article in various categories is really praiseworthy.
Their prompt and timely response to review's query and the manner in which they have set the reviewing process helps in extracting the best possible scientific writings for publication.
It's a honour and pride to be a part of the JCDR team. My very best wishes to JCDR and hope it will sparkle up above the sky as a high indexed journal in near future."



Dr. Arunava Biswas
MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata




Dr. C.S. Ramesh Babu
" Journal of Clinical and Diagnostic Research (JCDR) is a multi-specialty medical and dental journal publishing high quality research articles in almost all branches of medicine. The quality of printing of figures and tables is excellent and comparable to any International journal. An added advantage is nominal publication charges and monthly issue of the journal and more chances of an article being accepted for publication. Moreover being a multi-specialty journal an article concerning a particular specialty has a wider reach of readers of other related specialties also. As an author and reviewer for several years I find this Journal most suitable and highly recommend this Journal."
Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
Muzaffarnagar.
On Aug 2018




Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".



Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
Bengaluru.
On Aug 2018




Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".



Dr. Mamta Gupta
Consultant
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018




Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.


Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."



Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
E-mail: drrajendrak1@rediffmail.com
On May 11,2011




Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."



Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
E-mail: ravi.dr.shankar@gmail.com
On April 2011
Anuradha

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.


Dr. Anuradha
E-mail: anuradha2nittur@gmail.com
On Jan 2020

Important Notice

Original article / research
Year : 2022 | Month : September | Volume : 16 | Issue : 9 | Page : OC15 - OC20 Full Version

Safety and Efficacy of Enalapril Combined with Metoprolol in Patients of Hypertension Complicated with Coronary Heart Disease: A Randomised Clinical Trial


Published: September 1, 2022 | DOI: https://doi.org/10.7860/JCDR/2022/52689.16850
Ping Wang, Lijun Wang, Zhihui Liu, JI Feng

1. Doctor, Department of Cardiology, Jingdezhen Municipal First People’s Hospital, Jingdezhen, Jiangxi, China. 2. Doctor, Department of Cardiology, Jingdezhen Municipal First People&’s Hospital, Jingdezhen, Jiangxi, China. 3. Doctor, Department of Cardiology, Jingdezhen Municipal First People’s Hospital, Jingdezhen, Jiangxi, China. 4. Department of Cardiology, Jingdezhen Municipal First People’s Hospital, Jingdezhen, Jiangxi, China.

Correspondence Address :
Ping Wang,
317, North China Road, Jingdezhen City, Jiangxi Province,
China,Jingdezhen, Jiangxi, China.
E-mail: wangping_ys@126.com

Abstract

Introduction: Enalapril, which inhibits Angiotensin-Converting Enzyme (ACE), is a commonly used drug for the treatment of hypertension. Metoprolol, a β-blocker, is widely prescribed for patients with cardiac diseases. Essential hypertension has been identified as an independent risk factor of Coronary Heart Disease (CHD). Until now, there are few studies and reports on the application of the two drugs in patients with Hypertension and Coronary Heart Disease (HCHD).

Aim: To assess the safety and efficacy of enalapril combined with metoprolol in patients with HCHD.

Materials and Methods: The present single-centre randomised clinical trial was conducted on 109 patients with HCHD at Jingdezhen Municipal First People’s Hospital from April 2018 to January 2020. The participants were randomly divided into into two groups, one group on enalapril (n=58), and the other on enalapril and metoprolol combination (n=51). Patients in both groups were treated for eight weeks. The blood pressure, cardiac function index, serum C-Reactive Protein (CRP), Homocysteine (Hcy), and Matrix Metalloproteinase-9 (MMP-9) levels were compared between the two groups, and the adverse drug reactions of the two groups were statistically analysed using independent sample t-test or Mann-Whitney U test.

Results: The mean age of enalapril group was 64.78±7.29 years, and the gender ratio was 1:1.42. The mean age of enalapril/metoprolol combination group was 63.90±6.91 years, and the gender ratio was 1:0.96. After treatment, both systolic and diastolic blood pressure of the enalapril/metoprolol combination group were significantly lower than that of enalapril group (p<0.05). Enalapril combined with metoprolol significantly improved cardiac function and significantly decreased the levels of serum inflammatory markers (CRP 18.57±3.61 vs 27.50±3.60, p<0.001; Hcy 12.14±2.07 vs 13.83±2.17 mmol L-1, p<0.001; MMP-9 372.35±12.34 vs 436.69±13.89 pg L-1, p<0.001; Transforming Growth Factor ALPHA (TGF-a) 8.18±1.38 vs 10.40±1.44 mmol L-1, p<0.001). The overall rate of adverse reactions was not significantly different between the groups (enalapril/metoprolol combination group vs enalapril group, 15.69% vs 10.34%, p=0.406).

Conclusion: The combined treatment of enalapril and metoprolol was more effective than enalapril alone in reducing the inflammatory response, reducing blood pressure, and improving cardiac function in patients with HCHD. This combinational therapeutic strategy may be a better choice for patients with HCHD.

Keywords

β-blocker, Angiotensin converting enzyme, Cardiac function, Matrix metalloproteinase

Cardiovascular Diseases (CVDs) are the leading cause of death globally.An estimated 17.9 million people died from CVDs in 2019, representing 32% of all global deaths. Of these deaths, 85% were due to heart attack and stroke (1). CHD is recognised as one of the most common CVDs in humans (2),(3). The death rate of CHD in China increased by 31.6% from 1990 to 2010, and CHD rose from the seventh place to the second place in the list of causes of premature death in China (4). Essential hypertension has been identified as an independent risk factor of CHD (5),(6). HCHD can significantly reduce patients’quality of life, for example, symptoms of angina and heart failure (7), activity restrictions, and participation restrictions (8). Therefore, effective prevention and early detection of hypertension and CHD are imperative.

Enalapril, which is a (S)-1-{N-{1-(ethoxycarbonyl)-3-phenylpropyl}-l-alanyl}-l-proline, inhibits ACE, and reduces the level of angiotensin-II, and results in reduced peripheral resistance without increasing cardiac oxygen demand, and decreases aldosterone secretion and elevates serum renin levels (9). Metoprolol, a β-blocker, is widely prescribed for patients with cardiac diseases (10). Metoprolol reduces the excitability of sympathetic nerves, reverses cardiac remodeling and improves myocardial function by attenuating myocardial expression of proinflammatory mediators such as Tumour Necrosis Factor-α (TNF-α) (11). ACE inhibitors and β-blockers have been combined to treat heart failure (12),(13), hypertension (14), diabetes and coronary disease (15), and its safety has been extensively studied (16),(17).

Serum biomarkers have been studied throughout HCHD disease progression, and have a substantial impact on the diagnosis, treatment, and care of patients with HCHD (18). The rupture of the fibrous cap of the atherosclerotic plaque induces coronary thrombosis and results in acute coronary syndrome. MMP plays an important role in plaque instability. Plaque instability is the most common mechanism of CHD and results in tissue proteolysis, which is an important factor in the thinning and cracking of the hardened atheromatous fibrous cap (19). The expression of MMP-9 is increased in atherosclerotic plaques and areas of macrophage aggregation. Overexpression of activated MMP-9 can enhance the degradation of Endothelial Cells (ECM), thereby reducing the strength of plaques and promoting plaque rupture (20). In humans, CRP is a major acute-phase protein whose concentration may increase more than 1,000-fold in severe inflammatory states. CRP may be an atheroprotective molecule, as shown by studies using transgenic CRP in animal models of human-like atherosclerosis (21),(22). Clinical data have indicated that CRP could be a key predictive factor of atherosclerosis (23),(24),(25). Intraplaque CRP colocalises with oxidised low-density lipoprote in and macrophages in human atherosclerotic lesions. However, MMP-9 has been implicated in plaque rupture (23). Hcy is a risk factor of atherosclerosis and affects the evolution of carotid intimal-medial thickness in patients with CHD. The degree of vascular disease is positively correlated with Hcy (16),(17). Transforming Growth Factor-α (TGF-a) binds to epidermal growth factor receptor, activates intracellular signal transduction pathways, regulates the activity of transcription factors and cell proliferation, and participates in the pathological process of vascular remodeling (26).

Although enalapril in the treatment of hypertension and metoprolol in the treatment of cardiac diseases have been widely investigated, the literature search of enalapril combined with metoprolol in patients with HCHD indicates that data are scarce (27). This study sought to determine safety and efficacy of enalapril combined with metoprolol in patients with HCHD. Primary outcome measures were the effect of the drug combination on blood pressure and cardiac function, and the incidence of adverse events in patients with HCHD. Secondary outcome measures were to examine the effect on the concentrations of serum CRP, Hcy, MMP-9, and TGF-α in these patients.

Material and Methods

This was a single-centre, randomised, clinical trial. Patients with HCHD admitted to Jingdezhen Municipal First People’s Hospital from April 2018 to January 2020 were selected for participation in this study. All patients gave written informed consent prior to the start of the study. This study was approved by the Medical Ethics Committee of Jingdezhen Municipal First People’s Hospital {Code: LIPJ (2018) -01-01 (Ke)}. A parallel-group randomised design was used for this clinical trial.

Sample size calculation: The sample size estimation formula is based on completely random design sample mean comparison:

where, α=0.05 and β=0.1, N represents the total sample size of two independent groups, Zα/2 representsthe two-sided critical value of the standard normal distribution, Zβ representsthe one-sided critical value of the standard normal distribution, Q1-1 represents sample ratio, and Q1-1=n1/N, Q2-1=n2/N, and σ represents the standard deviation, and δ represents the between-group difference with clinical significance. Sample size estimation was performed using PASS 2007 software. Calculation produced a suggested sample size of 43 per group. Assuming a 30% dropout rate, the total sample size was finalised at 112 (28).

Because blinding of the dispatching personnel, the paramedics on scene, patients and the physicians is not possible for practical reasons, laboratory personnel, staff of the cardiac function indexes measurements, and outcome assessors remained blinded.

Inclusion criteria: Patients with hypertension based on the 2010 Chinese Hypertension Prevention and Control Guidelines with a systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg (29), and at least one main coronary artery lumen stenosis ≥50% on a coronary angiogram; patients who have not taken β-blocker or ACE inhibitors drugs within a month and age ≥18 and age <65-year-old were included.

Exclusion criteria: Rheumatic heart disease, pulmonary hypertension, diabetes mellitus, dilated cardiomyopathy, hypertrophic cardiomyopathy, myocarditis, severe valvular disease, hyperthyroidism, cancer, haematologic disease, left ventricular systolic dysfunction; psychosis or dysgnosia and patients refusing to sign the informed consent were excluded.

The flowchart for the selection procedure of the study participants has been shown in (Table/Fig 1).

Study Procedure

The patients were numbered according to the order in which they were admitted and were divided into- enalapril alone group and an enalapril/metoprolol combination group, using a random number table. The patient’s Diastolic Blood Presure (DBP) and Systolic Blood Presure (SBP) were measured in sitting position, and the Left Ventricular End Systolic Diameter (LVEDD), Left Ventricular End Diastolic Diameter (LVESD) and Ventricular Ejection Fraction (LVEF) were measured using echocardiography (IE33 Colour Doppler Ultrasound Diagnostic System, Philips Electronics Co., Ltd., Netherlands). A 5 mL of fasting venous blood was obtained from the patient, and the serum was separated at 3500 r/min, centrifuge radius 8 cm, and centrifuge time 10 minutes. A double antibody sandwich Enzyme-Linked Immunosorbent Assay (ELISA) was used to detect serum CRP, Hcy, MMP-9, and TGF-α levels (CRP, Hcy, MMP-9, TGF-α kits were provided by Wuhan Boster Biotechnology Co., Ltd., MR III microplate reader, Hyperion, USA).

All patients were given routine treatment, including diet control. Patients in the enalapril alone group were treated with enalapril tablets (10 mg/tablet) (Yangtze River Pharmaceutical Group, Jiangsu Pharmaceutical Co., Ltd., specification: 10 mg/tablet), and the dose was adjusted according to the blood pressure level. Patients in the enalapril/metoprolol combination group were treated with oral enalapril and metoprolol tartrate tablets (25 mg/tablet) (Astra Zeneca Pharmaceutical Co., Ltd., specification: 25 mg/tablet). The usage and dosage of enalapril tablets were the same as those in the enalapril alone group. The initial dose of metoprolol tablets was 25 mg/time, 3 times/day, and then gradually increased according to the control of blood pressure and Heart Rate (HR). The maximum dose did not exceed 150 mg QD. All patients were treated for eight weeks. During the treatment, all adverse drug reactions (e.g., bronchospasm, cough (30), dermatitis (31)) were monitored and recorded. After eight weeks, the patient's blood pressure, cardiac function indexes, serum CRP, Hcy, MMP-9, and TGF-α levels were measured.

Statistical Analysis

Data analysis was performed using Statistical package for social sciences (SPSS) (version SPSS 20.0, IBM SPSS Inc, Chicago, IL, USA) for statistical analysis. Percentage (%) was used to represent count data, (x±s) was used to represent measurement data, and the comparison between groups was performed by independent samples t-test. α=0.05 was the test level p<0.05 indicates that the difference is statistically significant, and p<0.01 indicates that the results have significant statistical differences.

Results

Characteristics of the patients: A total of 109 patients with HCHD were included in this study (58 in the enalapril alone group and 51 in the enalapril/metoprolol combination group). There was no statistical difference (p>0.05) for gender, age, course of the disease, BMI, HR, SBP, DBP between the two groups, (Table/Fig 2).

Comparison of blood pressure before and after treatment: Before treatment, there was no statistical difference in SBP and DBP between the two groups (p=0.321, 0.395). After treatment, the mean differences of SBP and DBP in the enalapril/metoprolol combination group after treatment were significantly greater than those in the enalapril alone group (p=0.026, 0.013) (Table/Fig 3).

Comparison of cardiac function indexes before and after treatment: Before treatment, there was no statistical difference in HR, LVEDD, LVESD, and LVEF between the two groups (p=0.769, 0.645, 0.737, respectively). After treatment, the decrease of LVEDD and LVESD in the enalapril/metoprolol combination group was significantly higher than that in the enalapril alone group, and the increase of LVEF was significantly higher than that in the enalapril alone group (Table/Fig 4).

Comparison of serum levels of inflammatory factors before and after treatment: Before treatment, the differences in serum CRP, Hcy, MMP-9, and TGF-α between the two groups were not statistically significant (p>0.05). After treatment, the decrease of the markers in the enalapril/metoprolol combination group was significantly greater than that in the enalapril alone group, but there was no significant difference in the decrease of serum TGF-α (p=0.370, >0.05) (Table/Fig 5).

Adverse events assessment: During treatment, there were eight patients with adverse drug reactions in the enalapril/metoprolol combination group were- three intractable dry cough, two rashes, two headache, and one taste alteration. There were six patients with adverse drug reactions in the enalapril alone group- three intractable dry cough, one rash, one taste alteration, and one headache. The total incidence of adverse drug reactions in the enalapril/metoprolol combination group and the enalapril alone group was 15.69% and 10.34%, respectively, and the difference was not statistically significant (p=0.406).

Discussion

Hypertension is the most common and independent cardiovascular risk factor for coronary artery disease (32). Cardiovascular risk factors should be managed while regulating blood pressure in the clinical treatment of HCHD (12). ACE inhibitors used to block the Renin-Angiotensin System (RAS) are effective treatments for hypertension, congestive heart failure, and myocardial infarction. However, studies have found that long-term (13 months) use of ACE inhibitors does not adequately prevent aldosterone production, which results in aldosterone escape (33),(34). Metoprolol is a β-adrenergic receptor blocker, which inhibits the release of angiotensin II by binding to the receptor, thereby reducing blood pressure, regulating HR and prolonging ventricular diastolic time (35).

Clinical studies have shown that metoprolol can increase coronary blood flow, increase left LVEF, and improve cardiac function. At present, it is often used in the clinical treatment of mild to moderate hypertension, tachycardia, angina pectoris, prevents recurrent myocardial infarctions, and arrhythmias (35),(36),(37). Researchers have studied the combined treatment of heart failure (12),(13), hypertension, diabetes or coronary disease with ACE inhibitors and β-blockers (15), and its safety (12),(13).

This study showed that the combination of enalapril and metoprolol in the treatment of HCHD for eight weeks can significantly reduce SBP and DBP, LVEDD, LVESD, and improve LVEF. However, the long-term efficacy remains to be further studied. This may be due to the synergistic effect of enalapril and metoprolol on reducing cardiac load and pulmonary vascular resistance, increasing coronary blood flow and LVEF, thereby improving cardiacindexes. This study showed that enalapril and metoprolol combination treatment can significantly reduce serum levels of inflammatory factors (CRP, Hcy, and MMP-9) in patients with HCHD.

Fung JW et al.,believe that β-blockade also has a time-limited effect in reducing RAAS activation similar to ACE inhibitors (38). The effect was present at four weeks, reduced at eight weeks, and not different from baseline at 52 weeks. The experimental plan was to compare the clinical and inflammatory markers levels pretreatment and eight weeks post-treatment. This potential limitation may affect the interpretation of the results of this study.

Many factors may affect the metabolism of Hcy, including several medications widely used in the treatment of CVD (39),(40),(41). Several studies have already shown that thiazide-type diuretics can significantly increase plasma Hcy levels (42), and the β-receptor blocker, metoprolol, decreases plasma Hcy levels (43). Fan FF et al.,found that enalapril can cause an increase in plasma Hcy levels among hypertensives with low baseline Hcy levels, and there is no significant association of MTHFR C677T genotypes with changes in Hcy levels in response to enalapril among the subjects with essential hypertension (44). Yet, in the study by Poduri A et al., there was a significant decrease of Hcy levels in mild essential hypertensive patientsafter ramipril treatment (5 mg/d) for six weeks, and they believe the decrease in Hcy induced by β-blockers and ACE inhibitors due to the improvement of endothelial function along with improved renal function (45). The present results are consistent with the study by Poduri A et al., (45). The exact mechanism remains to be elucidated.

There was no significant difference in the reduction of serum levels of TGF-α between two groups.This may be due to the relatively small concentrations of TGF-α, or it may be that the number of cases is small, and no significant difference can be found. The sample size will be increased in the future studies. The RAS consists of ACE, the octapeptide product angiotensin II (Ang II), and AT1 and AT2 receptors (46). MMP activity can be reduced by diminishing RAS signaling (47). Combining ACE inhibitors and β-blockers increasing the inhibition of RAS signaling may reduce serum levels of MMP-9. The decrease in Hcy induced by ACE inhibitors may be due to the improvement of endothelial function along with improved renal function following ACE inhibitor therapy (48). A study previously documented that the reduction of plasma Hcy levels by β-blocker therapy in hypertensive patients, however, the mechanism of its action needs to be further studied (45).

The results of this study also showed that the rate of adverse reactions in patients treated with enalapril combined with metoprolol was higher than that of patients treated with enalapril alone, but the difference between groups was not statistically significant. Enalapril combined with metoprolol in the treatment of HCHD did not significantly increase the risk of adverse reactions and had a good safety profile.

Limitation(s)

Although the study design excluded patients who did not take β-blocker or ACE inhibitor drugs within a month, it did not set a wash-out period for participants and did not exclude participants who took anti-platelet aggregation drugs or statins.

Conclusion

Enalapril combined with metoprolol is superior to enalapril alone for hypertension complicated with CHD. Although enalapril, was able to significantly reduce serum levels of inflammatory factors (CRP, Hcy, and MMP-9) in patients with HCHD, the magnitude of the reduction in serum levels of inflammatory factors (CRP, Hcy, and MMP-9) with enalapril combined with metoprolol was greater than the reduction with enalapril alone. In the future, researchers need to investigate the molecular mechanism underlying the interaction of ACE inhibitor and β-blocker.

References

1.
World Health Organization. Cardiovascular diseases (CVDs). 2021. https://www.who.int/news-room/fact-sheets/detail/cardiovascular-diseases-(cvds).
2.
Gao W, He HW, Wang ZM, Zhao H, Lian XQ, Wang YS, et al. Plasma levels of lipometabolism-related miR-122 and miR-370 are increased in patients with hyperlipidemia and associated with coronary artery disease. Lipids Health Dis. 2012;11:55. Doi: 10.1186/1476-511x-11-55. [crossref] [PubMed]
3.
Zhu K, Liu D, Lai H, Li J, Wang C. Developing miRNA therapeutics for cardiac repair in ischemic heart disease. J Thorac Dis. 2016;8(9):E918-27. Doi: 10.21037/jtd.2016.08.93. [crossref] [PubMed]
4.
Yang G, Wang Y, Zeng Y, Gao GF, Liang X, Zhou M, et al. Rapid health transition in China, 1990-2010: Findings from the Global Burden of Disease Study 2010. Lancet (London, England). 2013;381(9882):1987-2015. Doi: 10.1016/s0140-6736(13)61097-101. [crossref]
5.
Nargesi AA, Heidari B, Esteghamati S, Hafezi-Nejad N, Sheikhbahaei S, Pajouhi A, et al. Contribution of vitamin D deficiency to the risk of coronary heart disease in subjects with essential hypertension. Atherosclerosis. 2016;244:165-71. Doi: 10.1016/j.atherosclerosis.2015.11.020. [crossref] [PubMed]
6.
Kannel WB. Hypertension and other risk factors in coronary heart disease. Am Heart J. 1987;114(4 Pt 2):918-25. Doi: 10.1016/0002-8703(87)90588-6. [crossref]
7.
Thompson DR, Yu CM. Quality of life in patients with coronary heart disease-I: Assessment tools. Health Qual Life Outcomes. 2003;1:42. Doi: 10.1186/1477-7525-1-42. [crossref] [PubMed]
8.
Pai HC, Hu YF, Chao SY, Chen HM. Study on the correlation between continuity of care and quality of life for patients with coronary heart disease. Int J Environ Res Public Health. 2020;17(23):9125. Doi: 10.3390/ijerph17239125. [crossref] [PubMed]
9.
Faruqi A, Jain A. Enalapril. StatPearls. StatPearls Publishing; 2020.
10.
Bahar MA, Kamp J, Borgsteede SD, Hak E, Wilffert B. The impact of CYP2D6 mediated drug-drug interaction: A systematic review on a combination of metoprolol and paroxetine/fluoxetine. Br J Clin Pharmacol. 2018;84(12):2704-15. Doi: 10.1111/bcp.13741. [crossref] [PubMed]
11.
Wang Y, Liu J, Suo F, Hu HS, Xue M, Cheng WJ, et al. Metoprolol-mediated amelioration of sympathetic nerve sprouting after myocardial infarction. Cardiology. 2013;126(1):50-58. Doi: 10.1159/000351074. [crossref] [PubMed]
12.
Nochioka K, Sakata Y, Shimokawa H. Combination therapy of renin angiotensin system inhibitors and ??-blockers in patients with heart failure. Advances in Experimental Medicine and Biology. 2018;1067:17-30. Doi: 10.1007/5584_2018_179. [crossref] [PubMed]
13.
Dittrich S, Graf E, Trollmann R, Neudorf U, Schara U, Heilmann A, et al. Effect and safety of treatment with ACE-inhibitor Enalapril and ??-blocker metoprolol on the onset of left ventricular dysfunction in Duchenne muscular dystrophy - a randomised, double-blind, placebo-controlled trial. Orphanet Journal of Rare Diseases. 2019;14(1):105. Doi: 10.1186/s13023-019-1066-9. [crossref] [PubMed]
14.
Lazebnik LB, Mikheeva OM, Toporkov AS, Komissarenko IA, Vasnev OS, Fedulenkova LV. Correction of portal hypertension by beta-adrenoblockers (atenolol and metoprolol) and inhibitors of ACE (lisinopril and enalapril) in liver cirrhosis. Eksp Klin Gastroenterol. 2007;(5):57-66.
15.
Gustafsson F, Segura J, Ruilope LM. How should we manage heart failure developing in patients already treated with angiotensin-converting enzyme inhibitors and beta-blockers for hypertension, diabetes or coronary disease? Journal of Hypertension. 2010;28(8):1595-98. Doi: 10.1097/HJH.0b013e32833984b8. [crossref] [PubMed]
16.
Coop CA, Schapira RS, Freeman TM. Are ACE inhibitors and beta-blockers dangerous in patients at risk for anaphylaxis? J Allergy Clin Immunol Pract. 2017;5(5):1207-11. Doi: 10.1016/j.jaip.2017.04.033. [crossref] [PubMed]
17.
Correale M, Zicchino S, Monaco I, Di Biase M, Brunetti ND. Angiotensin-converting enzyme inhibitors, angiotensin II receptors antagonists, beta-blockers and ivabradine as supportive therapy in pulmonary hypertension: Drug safety and tolerability. Eur J Intern Med. 2017;44:e24-27. Doi: 10.1016/j.ejim.2017.07.016. [crossref] [PubMed]
18.
Baumgartner C, Lewis GD, Netzer M, Pfeifer B, Gerszten RE. A new data mining approach for profiling and categorizing kinetic patterns of metabolic biomarkers after myocardial injury. Bioinformatics. 2010;26(14):1745-51. Doi: 10.1093/bioinformatics/btq254. [crossref] [PubMed]
19.
Hamed GM, Fattah MF. Clinical Relevance of matrix metalloproteinase 9 in patients with acute coronary syndrome. Clin Appl Thromb Hemost. 2015;21(8):705-11. Doi: 10.1177/1076029614567309. [crossref] [PubMed]
20.
Shah PK, Falk E, Badimon JJ, Fernandez-Ortiz A, Mailhac A, Villareal-Levy G, et al. Human monocyte-derived macrophages induce collagen breakdown in fibrous caps of atherosclerotic plaques. Potential role of matrix-degrading metalloproteinases and implications for plaque rupture. Circulation. 1995;92(6):1565-69.
21.
Pathak A, Agrawal A. Evolution of C-Reactive protein. Front Immunol. 2019;10:943-43. Doi: 10.3389/fimmu.2019.00943. [crossref] [PubMed]
22.
Rifai N, Ridker PM. High-sensitivity C-reactive protein: A novel and promising marker of coronary heart disease. Clinical Chemistry. 2001;47(3):403-11. [crossref] [PubMed]
23.
Singh U, Dasu MR, Yancey PG, Afify A, Devaraj S, Jialal I. Human C-reactive protein promotes oxidised low density lipoprotein uptake and matrix metalloproteinase-9 release in Wistar rats. J Lipid Res. 2008;49(5):1015-23. Doi: 10.1194/jlr.M700535-JLR200. [crossref] [PubMed]
24.
Liu HH, Cao YX, Sun D, Jin JL, Zhang HW, Guo YL, et al. High-sensitivity C-reactive protein and hypertension: combined effects on coronary severity and cardiovascular outcomes. Hypertens Res. 2019;42(11):1783-93. Doi: 10.1038/s41440-019-0293-8. [crossref] [PubMed]
25.
Li Y, Qadir Nawabi A, Feng Y, Ma G, Tong J, Shen C, et al. Coronary tortuosity is associated with an elevated high-sensitivity C-reactive protein concentration and increased risk of ischemic stroke in hypertensive patients. J Int Med Res. 2018;46(4):1579-84. Doi: 10.1177/0300060517748527. [crossref] [PubMed]
26.
Hardie WD, Davidson C, Ikegami M, Leikauf GD, Le Cras TD, Prestridge A, et al. EGF receptor tyrosine kinase inhibitors diminish transforming growth factor-alpha-induced pulmonary fibrosis. Am J Physiol Lung Cell Mol Physiol. 2008;294(6):L1217-25. Doi: 10.1152/ajplung.00020.2008. [crossref] [PubMed]
27.
Cooper ME, Allen TJ, O’Brien RC, Papazoglou D, Clarke BE, Jerums G, et al. Nephropathy in model combining genetic hypertension with experimental diabetes. Enalapril versus hydralazine and metoprolol therapy. Diabetes. 1990;39(12):1575-79. Doi: 10.2337/diab.39.12.1575. [crossref] [PubMed]
28.
Zhang H, Jiang X, Da H, Dai R, Zhao N, Pan W, Fan J. Effect of comprehensive psychosomatic promotion in hypertension patients with anxiety and depression based on community: A randomized parallel controlled trial. Medicine. 2020;99(33):e21451. https://doi.org/10.1097/MD.0000000000021451. [crossref] [PubMed]
29.
Liu LS. 2010 Chinese guidelines for the management of hypertension. Zhonghua Xin Xue Guan Bing Za Zhi. 2011;39(7):579-615. Doi: 10.3760/cma.j.issn.0253-3758.2011.07.002.
30.
Wood R. Bronchospasm and cough as adverse reactions to the ACE inhibitors captopril, enalapril and lisinopril. A controlled retrospective cohort study. Br J Clin Pharmacol. 1995;39(3):265-70. Doi: 10.1111/j.1365-2125.1995.tb04447.x. [crossref] [PubMed]
31.
Nguyen DL, Wittich CM. Metoprolol-induced lichenoid dermatitis. J Gen Intern Med. 2011;26(11):1379-80. Doi: 10.1007/s11606-011-1742-5. [crossref] [PubMed]
32.
Volpe M, Trimarco B, Battistoni A, Mancia G. Clinical management of coronary heart disease in hypertension. High Blood Press Cardiovasc Prev. 2013;20(3):129-34. Doi: 10.1007/s40292-013-0020-5. [crossref] [PubMed]
33.
Xiu JC, Wu P, Xu JP, Guo Z, Lai W, Zhang Y, et al. Effects of long-term enalapril and losartan therapy of heart failure on cardiovascular aldosterone. J Endocrinol Invest. 2002;25(5):463-68. Doi: 10.1007/BF03344039. [crossref] [PubMed]
34.
Borghi C, Boschi S, Ambrosioni E, Melandri G, Branzi A, Magnani B. Evidence of a partial escape of renin-angiotensin-aldosterone blockade in patients with acute myocardial infarction treated with ACE inhibitors. J Clin Pharmacol. 1993;33(1):40-45. Doi: 10.1002/j.1552-4604.1993.tb03901.x. [crossref] [PubMed]
35.
Morris J, Dunham A. Metoprolol. StatPearls. StatPearls Publishing; 2020.
36.
Zhang Q, Lu XN, Sun NL. Effects of verapamil and metoprolol on HR variability in patients with coronary heart disease. Beijing Da Xue Xue Bao Yi Xue Ban. 2007;39(6):610-13. Doi: 10.3321/j.issn:1671-167x.2007.06.014.
37.
Billinger M, Raeber L, Seiler C, Windecker S, Meier B, Hess OM. Coronary collateral perfusion in patients with coronary artery disease: Effect of metoprolol. European Heart Journal. 2004;25(7):565-70. Doi: 10.1016/j.ehj.2004.02.003. [crossref] [PubMed]
38.
Fung JW, Yu CM, Yip G, Chan S, Yandle TG, Richards AM, et al. Effect of beta blockade (carvedilol or metoprolol) on activation of the renin-angiotensin-aldosterone system and natriuretic peptides in chronic heart failure. Am J Cardiol. 2003;92(4):406-10. Doi: 10.1016/s0002-9149(03)00658-1. [crossref]
39.
Ueland PM, Hustad S, Schneede J, Refsum H, Vollset SE. Biological and clinical implications of the MTHFR C677T polymorphism. Trends Pharmacol Sci. 2001;22(4):195-201. Doi: 10.1016/s0165-6147(00)01675-8. [crossref]
40.
Desouza C, Keebler M, McNamara DB, Fonseca V. Drugs affecting homocysteine metabolism: Impact on cardiovascular risk. Drugs. 2002;62(4):605-16. Doi: 10.2165/00003495-200262040-00005. [crossref] [PubMed]
41.
Dierkes J, Westphal S. Effect of drugs on homocysteine concentrations. Semin Vasc Med. 2005;5(2):124-39. Doi: 10.1055/s-2005-872398. [crossref] [PubMed]
42.
Westphal S, Rading A, Luley C, Dierkes J. Antihypertensive treatment and homocysteine concentrations. Metabolism. 2003;52(3):261-63. Doi: 10.1053/meta.2003.50060. [crossref] [PubMed]
43.
Atar I, Korkmaz ME, Demircan S, Atar IA, Bozbas¸ H, Aydinalp A, et al. Beta blocker effects on plasma homocysteine levels in patients with hypertension. Atherosclerosis. 2005;181(2):399-402. Doi: 10.1016/j.atherosclerosis.2005.01.035. [crossref] [PubMed]
44.
Fan FF, Huo Y, Wang X, Xu X, Wang BY, Xu XP, et al. Effect of enalapril on plasma homocysteine levels in patients with essential hypertension. J Zhejiang Univ Sci B. 2010;11(8):583-91. Doi: 10.1631/jzus.B1001003. [crossref] [PubMed]
45.
Poduri A, Kaur J, Thakur JS, Kumari S, Jain S, Khullar M. Effect of ACE inhibitors and ??-blockers on homocysteine levels in essential hypertension. Journal of Human Hypertension. 2008;22(4):289-94. Doi: 10.1038/sj.jhh.1002325. [crossref] [PubMed]
46.
Joshi S, Chittimalli K, Jahan J, Vasam G, Jarajapu YP. ACE2/ACE imbalance and impaired vasoreparative functions of stem/progenitor cells in aging. Geroscience. 2020:01-14. Doi: 10.1007/s11357-020-00306-w. [crossref] [PubMed]
47.
Kim JH, Kim JH, Kim SC, Yi YS, Yang WS, Yang Y, et al. Adenosine dialdehyde suppresses MMP-9-mediated invasion of cancer cells by blocking the Ras/Raf-1/ERK/AP-1 signaling pathway. Biochemical Pharmacology. 2013;86(9):1285-300. Doi: 10.1016/j.bcp.2013.08.022. [crossref] [PubMed]
48.
Jiang S, Hsu YH, Niu T, Xu X, Xing H, Chen C, et al. A common haplotype on methylenetetrahydrofolate reductase gene modifies the effect of angiotensin-converting enzyme inhibitor on blood pressure in essential hypertension patients- a family-based association study. Clin Exp Hypertens. 2005;27(6):509-21. Doi: 10.1081/CEH-200067686. [crossref] [PubMed]

DOI and Others

DOI: 10.7860/JCDR/2022/52689.16850

Date of Submission: Oct 02, 2021
Date of Peer Review: Dec 09, 2021
Date of Acceptance: Jan 03, 2022
Date of Publishing: Sep 01, 2022

AUTHOR DECLARATION:
• Financial or Other Competing Interests: Funded by Science and Technology project of Jiangxi Province Health Commission (Grant No. 20197251).
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? Yes
• For any images presented appropriate consent has been obtained from the subjects. Yes

PLAGIARISM CHECKING METHODS:
• Plagiarism X-checker: Oct 04, 2021
• Manual Googling: Dec 23, 2021
• iThenticate Software: Aug 24, 2022 (19%)

ETYMOLOGY: Author Origin

JCDR is now Monthly and more widely Indexed .
  • Emerging Sources Citation Index (Web of Science, thomsonreuters)
  • Index Copernicus ICV 2017: 134.54
  • Academic Search Complete Database
  • Directory of Open Access Journals (DOAJ)
  • Embase
  • EBSCOhost
  • Google Scholar
  • HINARI Access to Research in Health Programme
  • Indian Science Abstracts (ISA)
  • Journal seek Database
  • Google
  • Popline (reproductive health literature)
  • www.omnimedicalsearch.com