Co-administration of low doses of intranasal PT-141, a melanocortin receptor agonist, and sildenafil to men with erectile dysfunction results in an enhanced erectile response

Objectives. To evaluate the safety and pharmacodynamic effect of co-administration of subtherapeutic doses of PT-141, a cyclic heptapeptide melanocortin analogue, and sildenafil to patients with erectile dysfunction. Methods. Nineteen patients with erectile dysfunction who were responders to either Viagra or Levitra by self-report were given 25 mg sildenafil and 7.5 mg intranasal PT-141, 25 mg sildenafil and an intranasal placebo spray, and a placebo tablet and an intranasal placebo spray in a randomized cross-over design. Erectile activity in response to two 30-minute episodes of visual sexual stimulation was assessed by RigiScan during a 6-hour postdose period. Results. The erectile response induced by co-administration of PT-141 and sildenafil was significantly greater than the response elicited by administration of sildenafil alone. Co-administration of PT-141 and sildenafil was safe and well-tolerated and did not result in new adverse events or adverse events that were increased in frequency or severity compared with monotherapy. Conclusions. Co-administration of intranasal PT-141 and a phosphodiesterase type 5 inhibitor may constitute a treatment alternative for patients in whom higher doses of a single therapy are not effective or well tolerated. (c) 2005 Elsevier Inc.