Correlation between steady-state plasma concentrations (Css) of bromperidol and haloperidol

Optimisation of pharmacotherapy in psychiatry through therapeutic drug monitoring, molecular brain imaging and pharmacogenetic tests: focus on antipsychotics

BACKGROUND

For psychotic disorders (i.e. schizophrenia), pharmacotherapy plays a key role in controlling acute and long-term symptoms. To find the optimal individual dose and dosage strategy, specialized tools are used. Three tools have been proven useful to personalize drug treatments: therapeutic drug monitoring (TDM) of drug levels, pharmacogenetic testing (PG), and molecular neuroimaging.

METHODS

In these Guidelines, we provide an in-depth review of pharmacokinetics, pharmacodynamics, and pharmacogenetics for 50 antipsychotics. Over 30 international experts in psychiatry selected studies that have measured drug concentrations in the blood (TDM), gene polymorphisms of enzymes involved in drug metabolism, or receptor/transporter occupancies in the brain (positron emission tomography (PET)).

RESULTS

Study results strongly support the use of TDM and the cytochrome P450 (CYP) genotyping and/or phenotyping to guide drug therapies. Evidence-based target ranges are available for titrating drug doses that are often supported by PET findings.

CONCLUSION

All three tools discussed in these Guidelines are essential for drug treatment. TDM goes well beyond typical indications such as unclear compliance and polypharmacy. Despite its enormous potential to optimize treatment effects, minimize side effects and ultimately reduce the global burden of diseases, personalized drug treatment has not yet become the standard of care in psychiatry.

Comparison of prolactin concentrations between haloperidol and bromperidol treatments in schizophrenic patients

The antipsychotic drug, bromperidol, is a close structural analogue of haloperidol. These two drugs also have similarities in metabolic pathways and pharmacological properties. In the present study, the prolactin concentrations in plasma during bromperidol versus haloperidol treatments were compared in the same individuals. The subjects were 22 schizophrenic inpatients, who first received bromperidol 12 mg/day for at least 2 weeks followed by haloperidol 12 mg/day. The prolactin concentration in plasma during bromperidol treatment (median and range; 24 and 7-93 ng/ml, respectively) was significantly (P< .01) lower than during haloperidol treatment (32 and 8-102 ng/ml), although the difference was small. The mean (+/- S.D.) plasma concentration of bromperidol was significantly lower than that of haloperidol (20.8+/-8.0 vs. 28.0+/-13.1 nmol/l, P<.05). Prolactin concentrations during both treatment phases correlated well in individuals (r's=.813, P<.001), while no correlation was observed between plasma concentrations of haloperidol and bromperidol (r=.053, ns). These findings suggest that slightly higher prolactin concentration does not necessarily lead to increased risk of hyperprolactinemia during bromperidol treatment compared with haloperidol treatment. In addition, it is suggested that both drugs show similar pharmacodynamic response despite the difference in pharmacokinetics in the same individuals.