Risperidone
Risperidone. Atypical antipsychotic — D2 + 5-HT2A receptor antagonist. CYP2D6 substrate; active 9-OH metabolite (paliperidone) drives much of the… Oral half-life 20 h.
Atypical antipsychotic — D2 + 5-HT2A receptor antagonist. CYP2D6 substrate; active 9-OH metabolite (paliperidone) drives much of the effect. Schizophrenia, bipolar, and autism-associated irritability.
PK: CLASS 5 INSIDE A SINGLE ROW. The two stored numbers came from the same abstract but describe DIFFERENT ANALYTES, and that abstract supplies both alternatives explicitly — parent risperidone has a half-life of "about 3 hours in extensive metabolizers and 22 hours in poor metabolizers" with 66% bioavailability, while the ACTIVE MOIETY has a "mean terminal half-life, 20 +/- 2 1/2 hours; absolute oral and intramuscular bioavailability, 100%". The record stored the parent bioavailability beside the moiety half-life, which is neither row. It is resolved in favour of the ACTIVE MOIETY, because that is what drives effect, what almost every clinical paper reports, and what this record four occupancy rows are actually modelling — so F becomes 1. THE dexlansoprazole DIRECTION TEST IS NEGATIVE and is reported clean: the metabolite half-life is longer, not shorter, and paliperidone lower bioavailability is a property of its extended-release tablet rather than of the molecule. ka 1.4 is unsourced but implies 2.709 h, not a round number and not any quoted endpoint, so CLASS 9 IS RULED OUT. Its depot route is removed: that route release duration of 336 h is exactly the two-week DOSING INTERVAL its citation states three times, and its 504 h lag appears nowhere.
Pharmacokinetics
- Oral — t½ 20 h · F 100% · Vd 110 L
Sources: PMID:21118746, PMID:7530376, PMID:7520908, PMID:8935801, PMID:7690693, PMID:32608144