Large variations of plasma levels during maintenance treatment with depot neuroleptics.

BACKGROUND

Stability of neuroleptic medication has been associated with optimal clinical effect and minimal side-effects. Depot administration is assumed to yield better stability.

METHOD: Thirty patients on depot neuroleptic treatment were followed during three years with repeated measurements of plasma level and concurrent ratings of clinical symptoms and side-effects.

RESULTS

Of 120 blood samples 35 (29%) measurements were outside +/-2 s.d. measurement error (expected 5%). Perphenazine levels were more variable (46%) than haloperidol (25%) and flupenthixol (12.5%). No relationship was found between side-effect ratings and fluctuations of plasma levels.

CONCLUSION

Depot neuroleptic medication does not eliminate a clinically unwanted and sometimes marked variation in plasma level.