Pharmacokinetics of haloperidol and fluphenazine decanoates in chronic schizophrenia.

Abstract

In a double-blind comparison of haloperidol decanoate and fluphenazine decanoate given 4-weekly for 60 weeks as maintenance therapy in 38 chronic schizophrenic in-patients, plasma haloperidol, fluphenazine and prolactin levels were measured at regular intervals by radioimmunoassay. After the first injection, the mean plasma haloperidol level was highest at week 1 and fell gradually towards week 4. Mean pre-dose haloperidol levels changed little after week 8. Results suggested an absorption half-life of 4 weeks, although, in three cases steady state was only achieved after 11 monthly injections. Steady state levels of both haloperidol and fluphenazine correlated highly with dose. In two sub-groups observed at steady state, both drugs produced a biphasic pattern of plasma drug concentration between injections, a rapid rise on day 1 followed by stable elevated levels and a gradual return to pre-injection concentration by the end of week 4. In the fluphenazine sub-group there was a second peak on day 7 and a steeper decline, so that the mean area-under-curve in week 4 was 64% of that in week 1. Drug injections at steady state induced an increase in prolactin secretion in all of the fluphenazine sub-group and in half of those receiving haloperidol. Plasma prolactin changes resembled those for drug concentrations, but differences in times of peaks on day 1 resulted in weak correlations. Fluphenazine appeared more potent than haloperidol in provoking prolactin secretion.

• Authors: D H Wiles, R G McCreadie, A Whitehead
• Journal: Psychopharmacology (Psychopharmacology (Berl)) Vol. 101 Issue 2 Pg. 274-81 ( 1990) ISSN: 0033-3158 [Print] Germany
• PMID: 2349370 (Publication Type: Clinical Trial, Comparative Study, Controlled Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Prolactin
• haloperidol decanoate
• fluphenazine depot
• Haloperidol
• Fluphenazine

Topics

• Adult
• Aged
• Biological Availability
• Double-Blind Method
• Female
• Fluphenazine (analogs & derivatives, blood, pharmacokinetics, therapeutic use)
• Half-Life
• Haloperidol (analogs & derivatives, blood, pharmacokinetics, therapeutic use)
• Humans
• Male
• Middle Aged
• Prolactin (blood)
• Radioimmunoassay
• Schizophrenia (drug therapy, metabolism)