Introduction: Pretreatment plasma homovanillic acid (HVA) levels have been
reported to be a correlate of clinical response to typical antipsychotics f
or schizophrenic, bipolar manic, and mixed groups of psychotic patients. Bi
ological markers of clinical response to antipsychotics could be useful for
optimizing drug treatment. Method: Thirty-one consenting acute inpatient s
ubjects between ages 19 and 66 years with a DSM-III-R clinical diagnosis of
bipolar disorder, manic with psychotic features were entered into this dou
ble-blind study and were randomly assigned to receive either haloperidol 25
mg/day or haloperidol 5 mg for the 3-week study. Subjects also received on
e of the following concomitant medications: standard lithium, lorazepam 4 m
g/day, or placebo. Results: The primary multiple regression analysis, inclu
ding all subjects on both haloperidol doses, yielded a significant main eff
ect for pretreatment plasma HVA (n = 31, F = 5.7, P = 0.025), indicating th
at higher pretreatment plasma HVA was predictive of better clinical respons
e. In addition, the interaction between haloperidol dose and pretreatment p
lasma HVA was also significantly associated with clinical response (F = 12.
59, P = 0.0015). When the two haloperidol doses were analyzed separately, w
e found that pretreatment plasma HVA was only correlated with clinical resp
onse in the low haloperidol 5 mg/day group (n = 18, F = 11.73, P = 0.0038)
and was unrelated to clinical response to the high haloperidol 25 mg/day gr
oup, Limitations: The sample size was small. Results may have been confound
ed by prior antipsychotic treatment and concomitant use of lithium or loraz
epam. Discussion: These results suggest, that pretreatment plasma HVA could
be useful for dosing antipsychotics. Patients with high plasma HVA levels
would be good candidates for low-dose treatment because they are more likel
y to improve on such a dose, while patients with low plasma HVA levels migh
t warrant more rapid dosage escalation. (C) 2000 Elsevier Science B.V. All
rights reserved.