L-arginine fights nitrate tolerance

A Canadian study has suggested that L-arginine can help prevent nitrate tolerance in patients receiving continuous transdermal nitroglycerin (TD-GTN) therapy, a common treatment for angina.

Writing in the Journal of the American College of Cardiology, lead author Dr John O. Parker from Queens University, Kingston, Ontario, said his team had studied 14 patients with stable angina, receiving TD-GTN therapy while also receiving either supplemental L-arginine or a placebo.

The researchers then assessed the performance of the subjects on a treadmill after they had received the L-arginine but before the start of TD-GTN. They detected no difference in the time to onset of angina compared with baseline. But when the same patients were studied after TD-GTN, the treadmill-walking time increased at four hours and at 24 hours in the patients receiving L-arginine.

"The improvement in exercise performance both four hours and 24 hours after TD-GTN during continuous therapy, when patients were receiving L-arginine, is of statistical significance, but the confidence intervals are wide,"​ Parker wrote.

"The data suggests that L-arginine supplementation modified the development of tolerance to GTN, but it cannot be stated that this modification completely prevents tolerance. In order to make the latter statement, it would be necessary to compare the initial responses to TD-GTN and placebo in a blinded fashion in these patients."​