Serum concentrations of cis(Z)-flupentixol and prolactin in chronic schizophrenic patients treated with flupentixol and cis(Z)-flupentixol decanoate.

Nine chronic schizophrenic patients selected from three hospital departments were treated with flupentixol (orally and IV) and cis(Z)-flupentixol decanoate in Viscoleo (IM) in a three-phase pharmacokinetic study. Oral administration (single and repeated dosage) showed a relatively slow absorption with maximum serum concentration around 4 h after administration. Intravenous injection indicated multicompartment kinetics for cis(Z)-flupentixol. The biological half-lives calculated after the different doses were the same, indicating that the pharmacokinetics of cis(Z)-flupentixol does not differ between single and repeated administration and does not change when moderately higher doses are given. The bioavailability of orally administered cis(Z)-flupentixol was calculated to be about 40% with IV injection as reference. After IM administration maximum serum concentration was seen between 4 and 10 days in most patients. Calculation of a disappearance half-life gave very variable results, indicating that the release of the drug from the oil depot is not a monoexponential process. The intramuscular depot had a much lower bioavailability than IV injection, which means that steady state has not been obtained after 8 weeks of depot treatment. Serum prolactin concentrations were elevated during neuroleptic treatment, but no correlation was found between prolactin concentrations and the serum concentrations of cis(Z)-flupentixol. A correlation between the changes in clinical ratings and concentrations of cis(Z)-flupentixol or prolactin was not found.