Effect of the acute administration of haloperidol and pimozide on plasma GH levels in acromegaly.

In 11 untreated acromegalic patients the plasma GH levels were determined after the acute administration of bromocriptine, haloperidol, pimozide (only in 8 patients) and of placebo. A 50% or more suppression of the basal GH levels was arbitrarily defined as a positive response to bromocriptine. Five patients displayed a negative response to bromocriptine. Of these, 4 responded to both antidopaminergic drugs. We conclude that the acute administration of antidopaminergic drugs reduces the GH secretion in some bromocriptine-insensitive acromegalic patients. Therapeutical implications will require further studies.