An open study of the pharmacokinetics and the tolerability of raclopride extended release capsules in psychiatric patients

Following a 4-7 day drug-free washout period, eight male inpatients took an extended-release (ER) formulation of raclopride. After the initial 8 mg dose on day 1 of the study, repeated plasma samples were collected over the ensuing 36 h. Subsequently, patients received raclopride 8 mg b.i.d. through day 7, 12 mg b.i.d. through day 14, and, if tolerated, 16 mg b.i.d. through day 21. On days 7, 14, and 21, repeated plasma samples were drawn over the 12 h following the morning dose. Relative to the previously studied immediate release form of raclopride, the ER formulation delayed and extended the absorption of raclopride, and produced lower maximum raclopride concentrations. Linear kinetics were preserved across the dose range studied. Two patients could not tolerate the highest raclopride dose because of extrapyramidal side effects.