Research Article: Effect of Onopordon acanthium L. as Add on Antihypertensive Therapy in Patients with Primary Hypertension Taking Losartan: a Pilot Study

Date Published: March 18, 2018

Publisher: Tabriz University of Medical Sciences

Author(s): Roshanak Ghods, Manouchehr Gharouni, Massoud Amanlou, Niusha Sharifi, Ali Ghobadi, Gholamreza Amin.


Purpose: Onopordon acanthium L. is known for its medicinal properties. Our recent study showed that its seed extract is a novel natura angiotensin-converting-enzyme inhibitor (ACEI). This study was carried out to investigate its possible antihypertensive effects in patients receiving losartan.

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Hypertension (HTN) is a global concern and affects approximately 75 million adults in the United States and if left untreated increases risk of stroke, myocardial infarction, vascular disease, and chronic kidney disease.1,2 Diagnosis and treatment of high blood pressure are essential to prevent mortality and morbidity.2,3 Hypertension may be treated by using routine drugs such as angiotensin-converting-enzyme (ACE) inhibitors, beta-blockers, diuretics, calcium channel blockers, alpha-blockers, and peripheral vasodilators,3,4 improving lifestyle factors including weight loss, quitting smoking, reducing sodium intake, regular exercise and limiting alcohol consumption.5 These recommendations may be used alone or in combination with others4. Losartan is an oral medication that belongs to a class of drugs called angiotensin receptor blocker (ARBs) which was approved by the U.S. Food and Drug Administration (FDA) in April 1995. Losartan blocks the angiotensin receptor, relaxes muscle cells and dilates blood vessels and reduces blood pressure.6,7

Cytotoxicity of the extract was performed in mice by injecting different doses of OSE (0.5-13.5 g/kg) to measure the minimum toxic dose of OSE and LD50 was 8.44 ± 0.04 g/kg. Sampling began on May 21, 2013 and continued for five months, till October 23, 2013. 54 patients were assessed. Only 24 patients met the inclusion criteria whom four were not willing to participate in the study. At the end, 18 patients (of 20) completed the study and two patients were left the study due to increased blood pressure more than 160/100 mmHg in one patient after 2 days and another, after 3 days from starting point. Based on the ethical issues and respect to the patients’ right, they were excluded and researcher referred both of them to the cardiologist to be treated with two or more drugs (Figure 1).

OSE synergistically with diuretic and plasma ACE inhibitor activity reduced blood pressure (both systolic and diastolic) in the patients under treatment with losartan, and did not show remarkable side effects in patients with primary hypertension. Because of the low number of samples, this medication may be not safely recommended. Further clinical trials is needed for increasing certainty with larger sample size and placebo.

This study was part of a postgraduate thesis entitled: ”Investigating the Effect of Onopordon Acanthium Seed on Primary Hypertension Reduction in Patients under Treatment by Losartan”; and was supported by a grant from Tehran University of Medical Sciences. The funding source had no involvement in any part of the study. We would like to thank the participants for their contribution to the maintenance of our patient record without which this project would have been impossible. Special thanks to Mr. Hadi Salehi, for his kindly efforts for extraction and drug preparation. We would like to thank Dr. Mohsen Amin assistant Prof. at Faculty of Pharmacy, Tehran University of Medical Sciences for his help in data analysis and manuscript editing.

The study protocol was approved by the ethics committee of Research Institute for Islamic and Complementary Medicine of Iran University of Medical Sciences at 09/10/2012 with reference number 732/P26/M/T.

The authors have declared no conflicts of interest.




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