Haloperidol

pharmacological · nervous · digestive · Oral · Intramuscular · IV

Haloperidol. High-potency typical antipsychotic — strong D2 antagonist with minimal anticholinergic / antihistamine activity. EPS + tardive… Oral half-life 18 h.

High-potency typical antipsychotic — strong D2 antagonist with minimal anticholinergic / antihistamine activity. EPS + tardive dyskinesia risk; QT prolongation at high IV doses. CYP3A4 + CYP2D6 substrate. IM decanoate enables monthly depot dosing.

PK: THE LARGEST SIMULATION ERROR IN THIS BATCH. The stored 12.9 L is verbatim in its abstract, but it is an apparent volume INTERNALLY INCONSISTENT WITH THAT SAME ABSTRACT own exposure figure by roughly 740-fold; read as per-kilogram the two reconcile, so the published units are almost certainly mislabelled. The true intravenous-derived value is "mean steady-state volume of distribution was 17.8 +/- 6.5 l/kg", about 1250 L, so the stored figure understated the distribution space by two orders of magnitude — and it was additionally paired with a bioavailability, a double-division, and reused unchanged on every route. Everything is now taken from one study with both routes (PMID:6831826): "Mean elimination t1/2 for the subjects was 17.9 +/- 6.4 (SD) hr" and "Bioavailability was 0.65 +/- 0.14 after oral doses"; the stored 29.6 h was an oral terminal value from a bioequivalence study. THE INTRAMUSCULAR ROW WAS A DEPOT CHIMERA: its zero-order duration of 672 h is the DECANOATE FOUR-WEEKLY DOSING INTERVAL read as an input duration, and that product is released FIRST-ORDER with an apparent half-life of three weeks, not zero-order. This row now models immediate-release intramuscular haloperidol only; the decanoate needs its own record. The effect-compartment citation states no equilibration value at all and its evidence points the other way, occupancy remaining high at 27 h against an 18 h plasma half-life.

Pharmacokinetics

Sources: PMID:15918525, PMID:1533719, PMID:1361536, PMID:8301582, PMID:8935801, PMID:6831826