The
angiotensin converting enzyme inhibitors (ACEIs) and
angiotensin receptor blockers (ARBs) are a well known entity and have been used in
therapeutics for various indications like
hypertension,
myocardial infarction and CHF. However, there is a renewed interest in these compounds in terms of their effects on pain perception in animals as well as in human beings. They have yielded contradictory results, showing
hyperalgesia in some studies but
analgesia in others. Hence this study was undertaken to evaluate the effect of
Ramipril (an ACE-I) and
Losartan (an ARB) on pain perception in human volunteers using cola caps and handcuff of sphygmomanometer. A total of 30 healthy, normotensive individuals with no previous history of intake of
analgesics during or 4 weeks prior to the study were selected after an informed consent. The first group received a single dose of placebo, the second group received
Ramipril (2.5 mg) & the third group received
Losartan (50 mg). Pain perception threshold (the point at which an individual first experiences
pain) and the maximum tolerated
pain were assessed using the above method. The control group showed no significant changes in pain threshold, but the group receiving either
Ramipril or
Losartan showed a decline in threshold for maximum tolerated
pain. Only
Ramipril and not
Losartan decreased the pain perception threshold. Our study revealed that single dose treatment of healthy volunteers with
Ramipril and
Losartan may cause algesia as early as after ingestion of the first dose and further studies are needed to study their long term effects on pain perception.