Aim: Is to investigate topical papaverine (PAP), a phosphodiastase (PDE) inhibitor as an alternative agent for chemical 
sphincterotomy in comparison with topical nitroglycerine(NTG), as PAP is hypothesized to be more effective, cheaper with fewer side effects. 
Methods: A prospective assessment of 65consecutive patients with chronic anal fissure (CAF) randomized to receive topical therapy with either 3% PAPcream or 0.2% NTG from July. 2002 to August. 2003. 
Results: In PAPgroup, in 26/30(86.7%) treatment was labeled "successful" with 19 (63.3%) showing actual fissure healing and 7(23.3%) showing only symptomatic improvement. None experienced headache but one reported face flushing &one reported tachycardia and 2reported perianal allergic dermatitis. In NTG group in 20/29(68.9%)treatment labeled" successful" with15(51.7%) showing actual healing and 5(17.2%)showing only symptomatic improvement. 19/29(65%)reported headache&10 reported face flushing&6 reported tachycardia and2 reported perianal dermatitis. Recurrence was not a problem as nearly all patients responded to repeat topical therapy. 
Conclusion: Topical PAP as a novel agent for chemical sphincterotomy seems to be superior to NTG, it offers comparable healing rates, faster onset of action and doesn't have significant side effects, suggesting that it may become the first line 
treatment of choice for CAF and open the door for further research on the use of other PDE inhibitors or even other 
altremative smooth muscle relaxants for chemical sphincterotomy.