EVOLUTION OF PLASMA HOMOVANILLIC-ACID (HVA) IN CHRONIC-SCHIZOPHRENIC PATIENTS TREATED WITH HALOPERIDOL

In a 4-week study of 14 drug-free schizophrenic patients (according to DSM-III-R), free and conjugated fractions of plasma homovanillic acid (pHVA) were repeatedly measured. Free HVA levels decreased during the first 2 h of haloperidol intake (P<0.03). Conjugated HVA levels slowl y decreased during the following weeks (P<0.05), while free HVA levels remained stable. After 4 weeks, free HVA levels remained unchanged 2 h after morning haloperidol intake, but conjugated HVA levels tended t o increase. In haloperidol responders, at baseline the free/total HVA ratio was significantly higher than that in non-responders (P<0.01). T olerant patients, i.e. those whose post-treatment free HVA levels decr eased below pretreatment levels, were not found to respond better to h aloperidol than nontolerant patients. The balance between free and con jugated pHVA may be a better reflection of the action of haloperidol t han free pHVA levels and it may be of prognostic value in terms of dru g response.