Prolactin monitoring of haloperidol and pimozide treatment in children with Tourette's syndrome.

Neuroleptic therapy of children and adolescents with Tourette's syndrome (GTS) is associated with unpredictable outcome and adverse drug responses (i.e., extrapyramidal symptoms). Assessing the potential outcomes in GTS from a physiologic marker such as plasma prolactin concentration is important in limiting exposure and optimizing therapy. In a double-blind, placebo-controlled, double crossover comparison of pimozide and haloperidol therapy, prolactin, tic severity, and extrapyramidal symptoms were assessed at a 6-week end point. Twenty-six GTS patients (10.5 +/- 2.6 years), experienced clinical response rates of 69% on 3.4 +/- 1.6 mg pimozide and 65% on 3.5 +/- 2.2 mg/day haloperidol. Pimozide responders demonstrate elevated prolactin (26.1 +/- 11.8 ng/mL) versus pimozide nonresponders (10.5 +/- 3.8 ng/mL) (p = .05) and haloperidol treated patients (p = .05). Prolactin may be a marker for tic response to pimozide, and conversely, a potential marker for haloperidol-related incidence of extrapyramidal symptoms during haloperidol therapy.