Effects of haloperidol decanoate on plasma homovanillic acid in chronic schizophrenic patients

Abstract

The effects of acute and chronic oral antipsychotic treatment on plasma homovanillic acid (pHVA) have been extensively studied over the past several years, However, the pHVA response to depot preparations remains unknown. This study reports an elevation in pHVA after haloperidol decanoate (HLD) administration in chronic schizophrenic patients. Thirteen stable chronic schizophrenic patients diagnosed by DSM-III-R criteria participated in th~s study. Informed consent was obtained from each patient. The study consisted of nine men and four women with a mean age of 37.2 -+ 6,9 years and weight of 61.3 --10.0 kg, These patients had been institutionalized at Chingyang Psychiatric Hospital for 9.0 --7.0 years and had been free of oral neuroleptics for at least 4 weeks and free of depot neuroleptics for at least 6 months prior to beginning the study. All subjects were placed on a low-monoamine diet and received noncaffeinated and nonalcoholic beverages for 4 weeks prior to and during the study. Intramuscular injections of HLD (Haldol decanoas) 100 mg were given every 4 weeks. After five injections, HLD was discontinued. The only concurrent medications were trihexyphenidyl (4 mg/day) and nitrazepam (5 rag/day), which do not influence haloperidol (HL) plasma concentrations (Cps) (Froemming et al 1989) and has not been reported to change pHVA levels. Venous blood was sampled on days 0 (baseline), 2 and 4, and the end of weeks 1 , 2 , 3 , 4 . 5 . 6 , 7 , 8 , 9 , 10, 11, 12, 13, 14, 15, 16, 17, 19, 20, 21, 23, 25, 27, and 29. Blood samples were collected into ethylenediaminetetraacetic acid (ETDA) tubes, and plasma was separated by a centrifuge at 3,000 RPM for 15 min. All specimens were kept at 50 ° C until assayed. Cps of HVA and HI, were determined with high performance liquid chro-