Purpose:
Exogenous nitric oxide donors, such as glyceryl trinitrate, have been used as treatment for anal fissures; however, headaches develop in 60 percent of patients. nitric oxide produced from the cellular metabolism of l-arginine mediates relaxation of the internal anal sphincter. this study investigated whether topical l-arginine gel reduces maximum anal resting pressure in volunteers.
Method:
In a two-center study, volunteers received a single topical dose of l-arginine or placebo (aquagel ). anal manometry was performed for two hours after application of 400 mg of l-arginine gel or placebo gel to the anal verge in 25 volunteers. side effects were recorded after single application and also after repeated dosing for three days.
Results:
L-arginine reduced maximum anal resting pressure by 46 percent from a median of 65 cm of water to a minimal value of 35 cm of water ( p< 0.001, wilcoxon's signed-rank test). the difference between l-arginine and placebo using repeated-measures testing was significant at p< 0.005. no side effects occurred with either gel; in particular, no episodes of headache were recorded.
Conclusion:
Topical l-arginine gel significantly lowers maximum anal resting pressure; its onset of action is rapid, and duration is at least two hours ( p< 0.01). l-arginine may have therapeutic potential, but further evaluation is needed before it can be used as a possible alternative treatment for chronic anal fissure.