Effect of apomorphine, a dopamine receptor agonist, on penile tumescence in normal subjects

Prog Neuropsychopharmacol Biol Psychiatry. 1984;8(4-6):695-9. doi: 10.1016/0278-5846(84)90040-x.


Apomorphine HCl (Apo) (0.25, 0.5 or 0.75 mg sc), a dopamine (DA) receptor agonist, induced penile erections (PEs) (monitored by mercury strain gauges and continuous recording on paper strip charts) in 7 out of 9 normal subjects and placebo in 1 of these 9 (p less than 0.05). Apo-induced PEs recurred in each of the 6 subjects retested. Benztropine (2 mg iv) had no effect on Apo-induced penile tumescence (PT). These data suggest (a) DA mechanisms play a role in normal erectile function (b) DA-mediated PT is not modulated by cholinergic systems (c) evaluation of the erectile response to Apo may provide a simple ancillary test to the investigation of impotence and a way of identifying a subpopulation of impotent subjects with impaired DA function who may respond to long-acting DA agents (d) Apo-induced PT may provide a novel way of studying DA function in man.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Apomorphine / pharmacology*
  • Benztropine / pharmacology
  • Bromocriptine / pharmacology
  • Cholinergic Fibers / physiology
  • Dopamine / physiology*
  • Drug Interactions
  • Humans
  • Levodopa / pharmacology
  • Male
  • Middle Aged
  • Penis / drug effects*
  • Penis / physiology


  • Benztropine
  • Bromocriptine
  • Levodopa
  • Apomorphine
  • Dopamine