title: Comparison of plasma levels between oral solution and fine granule dosage forms of risperidone.
abstract: Objective. In Japan, there are several clinical reports that risperidone (RIS) oral solution (OS) requires shorter time for tranquilization and induces fewer extrapyramidal symptoms (EPS) than other dosage forms; i.e. fine granules (FG). Our aim is to compare plasma levels of RIS, its active metabolite (9-OH-RIS), and their sum (active moiety; AM) between RIS-OS and RIS-FG in a multiple-dose regimen. Method. A 12-week cross-over study was conducted in nine patients with schizophrenia treated with 3 mg of RIS twice daily. The study period was divided into four terms, each term being 3 weeks. RIS-FG and RIS-OS were given in two alternate terms each. Blood samples were collected on the last day of each term just before and at 1 h after RIS treatment to measure plasma levels of RIS, 9-OH-RIS, and prolactin. Result. Plasma levels of RIS, 9-OH-RIS, AM, and prolactin before treatment were significantly lower for RIS-OS than for RIS-FG, while no significant difference was observed between the two forms at 1 h after administration. Conclusion. In a multiple-dose regimen, RIS-OS treatment caused a larger diurnal fluctuation in plasma level of AM than RIS-FG. These variations may explain the differences in severity of EPS between the 2 forms.
authors.affiliation: Department of Psychiatry, Moro Hospital, Saitama, Japan.
authors.forename: Hiroo
authors.initials: H
authors.lastname: Yoda
authors.forename: Hakuei
authors.initials: H
authors.lastname: Yamashita
keywords: 9-hydroxyrisperidone; Dosage forms; pharmacokinetics; prolactin; risperidone