The relationship between haloperidol blood levels and clinical responses

Haloperidol blood levels in patients were determined to elucidate the relationship between blood levels and clinical effects. Determinations of haloperidol serum were performed by radioimmunoassay and the clinical status was estimated using BPRS. The relationship between haloperidol serum levels and BPRS total score was studied in 20 chronic schizophrenics currently receiving haloperidol treatment. The results did not show positive relationship between these two. Another 11 schizophrenic patients were treated with daily doses of average 6 mg of haloperidol. The patients were classified into improved and unchanged group according to the changes of BPRS total score. All 7 cases classified into the improved group had short duration of the illness less than one year. In this group, the levels were lower initially but gradually rised in paralled with the increase of extent of recovery on BPRS. Furthermore, improvement of psychopathology by means of decrease of BPRS total score was still found after haloperidol serum levels reached a plateau. The results did not support the view that high blood concentration of haloperidol might contribute to the clinical effects, but still suggested utility of measuring blood levels in acute or subacute patients being treated with haloperidol medications.