High dose flupenthixol decanoate in chronic schizophrenia.

In a double-blind trial, female 'drug-resistant' chronic schizophrenic in-patients were given high dose or standard dose flupenthixol decanoate for 13 weeks. Plasma flupenthixol levels showed a five-fold interindividual variation, but were consistently higher with the high dose. Analysis of final scores showed no statistically significant differences between groups with regards to mental state, ward behaviour and extrapyramidal side-effects. When compared with pre-trial scores, the extrapyramidal side-effects worsened significantly in the high dose patients and social withdrawal decreased in the standard dose patients. The mental state of a sub-group of patients, possibly drug resistant for pharmacokinetic reasons, improved significantly on the high dose over the 13 weeks.