Erection-inducing methods and compositions

Methods and compositions for inducing penile erections, sufficient for vaginal penetration, in a human male suffering from impotence are provided. Kits containing the compositions in containers for single dosage administration are provided. Compositions for treating impotence that is of psychogenic or neurogenic origin contain a neuropeptide, vasoactive intestinal peptide and/or peptide N-terminal histidine C-terminal methioneamide and are formulated in a pharmaceutically acceptable carrier that has a pH of about 2 to about 4.5, preferably between about 2 and about 3.5, and most preferably about 3. Compositions for treating impotence of almost origin, including severe atherosclerosis, contain a neuropeptide, vasoactive intestinal peptide and/or peptide N-terminal histidine C-terminal methioneamide, and an alpha -adrenergic blocker, such as phentolamine or prazosin. In practicing the methods, the composition is administered by intracavernosal injection accompanied by or followed by sexual stimulation.