Table 1. Summary of emerging therapy for ED: centrally acting agents.
| Compound | Type of study | Route and dosage of administration | Population studied | Main findings | Date (year) | Author |
|---|---|---|---|---|---|---|
| PT-141 | Phase I | Intranasal 7–20 mg | Healthy men (n=30) | Mean duration of base rigidity ≥60% increased from 49.4 to 137.7 min for subjects receiving the 7–20 mg PT-141 doses (placebo: 20.6 min). | 2004 | Diamond et al [54] |
| Flushing and nausea were the most common adverse events reported. | ||||||
| Phase IIA | Viagra-responsive ED (n=24) | Mean duration of ≥60% base rigidity was 26.0 and 53.8 min for patients receiving the 7 and 20 mg PT-141 doses (placebo: 18.5 min). | ||||
| Flushing and nausea were the most common adverse events reported. | ||||||
| PT-141 | Phase I | Subcutaneous 0.3–10 mg | Healthy men (n=48) | Erectile response increased at doses greater than 1.0 mg. | 2004 | Rosen et al [55] |
| Mean duration of base rigidity ≥60% increased from 18 to 73 min for subjects receiving the 1.0–10.0 mg PT-141 doses (placebo: 6 min). Single doses up to 10 mg were safely administered and welltolerated. | ||||||
| Phase IIA randomized, double-blind, placebo-controlled crossover study | Subcutaneous 4 or 6 mg | Non-responder to viagra (n=25) | Mean durations of base rigidity at ≥80% were 14 and 17 min for patients receiving the 4 and 6 mg PT-141 doses (placebo: 2 min). | |||
| Single doses up to 6 mg were safely administered and well-tolerated. | ||||||
| PT-141 | Randomized, double-blind, placebo controlled study | Intranasal 10 mg | Non-responder to sildenafil (n=342) | Positive clinical results (ability to attain and maintain an erection and intercourse satisfaction) were seen in 51 patients (34%) in the PT-141 group compared with 13 patients (9%) in the placebo group. | 2008 | Safarinejad and Hosseini [56] |
| Co-administration of PT-141 and a PDE5-I | Intranasal 7.5 mg (with 25 mg sildenafil) | Responders to sildenafil or vardenafil (n=19) | Mean duration of basal rigidity ≥60% was 113 min in co-administration group (sildenafil alone: 70 min). | 2005 | Diamond et al [57] | |
| No new adverse event was noted. |
ED: erectile dysfunction, PDE5-I: phosphodiesterase type 5 inhibitor.