Recent work has demonstrated artificial penile erection after intracavernous injection of prostaglandin E1 (PGE1). A possible dose-response relationship between PGE1 and its erectile action was examined in a double-blind, cross-over designed, placebo-controlled study. 2. Twenty patients aged (mean +/- s.d.) 45 +/- 10.5 years suffering from psychogenic erectile dysfunction were tested on four occasions. Subjects received four intracavernous injections of saline containing either no other substance, preservative, 5 micrograms or 10 micrograms PGE1. 3. Investigations revealed clear dose-dependency of PGE1 in the grade and duration of erection achieved as well as in the latency between injection and achievement of erection (P less than 0.001). Saline and preservative did not induce erection. 4. Some local pain of varying grades did occur in 11/20 patients after 5 micrograms PGE1 and in 14/20 patients after 10 micrograms PGE1 injected intracavernously. This side-effect was caused by PGE1 itself and also showed a clear dose-relation (P = 0.0035). 5. Prostaglandin E1 appears to be a promising substance for diagnostic and therapeutic purposes in erectile dysfunction. Despite the discomfort observed in some patients, PGE1 is very effective even in low doses. PGE1 10 micrograms is suggested as the appropriate initial diagnostic dose for intracavernous injection to differentiate between the normal and pathological cavernous-vascular system.
