Introduction: Intracavernosal injection for pharmocological erection is an important tool for diagnosis and treatment of erectile dysfunction. Commonly the three drugs Papaverine, Phentolamine and Prostaglandin E1 have been used either alone or as combinations.

Aim: To determine the efficacy and safety of a bimix combination of Papaverine and Chlorpromazine administered intracavernosally in patients with erectile dysfunction( ED) of various origins as compared to Papaverine alone.

Methods: This was a randomized prospective comparative dose titration study as a part of diagnostic armamentarium in the evaluation of erectile dysfunction. Two hundred forty patients diagnosed with Erectile dysfunction were enrolled Injection was subsequently titrated to the dose producing an effective response i.e. an erection sufficient for vaginal penetration lasting for atleast 20 minutes with atleast 48 hrs interval between the successive doses. The response was measured in terms of time for erection(latency period),grade of erection and duration of erection. Any adverse effect or complications were noted.

Results: Satisfactory erectile response was 85% with Papaverine-CPZ combination in the dose range of 0.1 to 1 ml and and 65% with Papaverine alone in the dose range of 15 to 60 mg respectively. Of 42 men who had failed erection with 60mg of Papaverine, 18 produced erection with Papaverine-CPZ combination. Incidence of prolonged erection were 10% and 12.5% in PPV and Combination groups respectively. Altogether 56 adverse events occurred. 12.5% in PPV alone and 15% in combination group had erection lasting for more than 4 hrs and were aborted by intracavernosal injection of Phenylephrine. 10 in PPV alone and 5 in Combination had penile pain. Eight patients in PPV group had penile haematoma which resolved spontaneously whereas there was no haematoma reported in the combination group. Patients were followed up for a maximum of four years. Seven patients developed fibrotic plaque in the PPV group and there was none in the combination group.

Conclusion: Papaverine-CPZ combination has proved a cheap and effective alternative to other combinations with better efficacy than Papaverine alone. Side effects like penile pain, hematoma and fibrotic plaque formation was significantly less in the combination group.