A dose rising study of the safety and effects on serum prolactin of SK&F 101468, a novel dopamine D2-receptor agonist.

1. SK&F 101468, a non phenolic indolone derivative, has been characterised preclinically as a novel, potent and specific dopamine D2-receptor agonist. 2. Its tolerability and effects on serum prolactin were investigated in 14 healthy male volunteers in a study of the first administration of SK&F 101468 to man. 3. Doses between 80 micrograms and 2.5 mg caused statistically significant (P less than 0.05) lowering of basal and food stimulated serum prolactin, relative to placebo, over a 6 h post treatment period. 4. SK&F 101468 was well tolerated up to 1 mg with symptoms of nausea and postural hypotension at higher doses.