Comparison of serum levels after intramuscular injections of 2% and 10% cis(Z)-flupentixol decanoate in Viscoleo to schizophrenic patients.

The serum concentrations of cis(Z)-flupentixol after injection of 2% and 10% cis(Z)-flupentixol decanoate in Viscoleo (Depixol injection, Fluanxol Depot) have been investigated in a crossover study with eight schizophrenic patients. No statistically significant difference was found between the two preparations when the data from individual days or areas under the serum concentration curves were considered. For the individual patients a difference was found between the two treatments in six cases; one preparation gave the higher serum concentration in four cases and the other preparation in two cases. Thus, the difference found within individual patients reflects the intraindividual variation rather than a difference between preparations. The maximum serum concentration was seen at 4 or 7 days after injection. The maximum/minimum fluctuation ratio indicates that dosage intervals longer than 2 weeks seem reasonable for most of the patients. The similarity in the serum concentrations, no matter which concentration of flupentixol decanoate solution was given, indicates that a dispersal and possibly a metabolic breakdown of the oil depot takes place in the muscle.