THIOTHIXENE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for THIOTHIXENE HYDROCHLORIDE (THIOTHIXENE HYDROCHLORIDE).
Thiothixene hydrochloride is a typical antipsychotic that blocks postsynaptic dopamine D2 receptors in the central nervous system (CNS), particularly in the mesolimbic and mesocortical pathways. It also has alpha-adrenergic blocking activity and weak anticholinergic effects.
| Metabolism | Primarily metabolized by the liver via sulfoxidation, N-demethylation, and hydroxylation; involves cytochrome P450 enzymes, likely CYP1A2 and CYP3A4. |
| Excretion | Renal: primarily as metabolites, <1% unchanged; fecal: minor; biliary: some metabolites excreted in bile. |
| Half-life | Terminal elimination half-life: 34 hours (range 25–50 hrs) in adults; clinical context: allows once-daily dosing. |
| Protein binding | ~90% bound to albumin and alpha1-acid glycoprotein. |
| Volume of Distribution | Vd: 10–20 L/kg; indicates extensive tissue distribution. |
| Bioavailability | Oral: ~50% due to first-pass metabolism; IM: 100%. |
| Onset of Action | Oral: 30–60 minutes for antipsychotic effect; IM: 20–30 minutes. |
| Duration of Action | Oral: 12–24 hours; IM: up to 24 hours; clinical notes: duration may be longer with chronic use. |
Initial: 2-5 mg orally 3 times daily; maintenance: 15-30 mg orally per day in divided doses; maximum: 60 mg orally per day.
| Dosage form | CONCENTRATE |
| Renal impairment | No specific dose adjustment recommended; monitor for increased adverse effects with severe renal impairment. |
| Liver impairment | Child-Pugh Class A: no adjustment; Child-Pugh Class B: reduce dose by 25-50%; Child-Pugh Class C: reduce dose by 50-75%. |
| Pediatric use | Children >12 years: initial 2 mg orally 3 times daily; maintenance 15-30 mg/day in divided doses; maximum 60 mg/day. For children <12 years: not recommended. |
| Geriatric use | Initial dose: 1-2 mg orally 1-2 times daily; increase slowly; maximum 15 mg/day due to increased sensitivity and risk of adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for THIOTHIXENE HYDROCHLORIDE (THIOTHIXENE HYDROCHLORIDE).
| Breastfeeding | Thiothixene is excreted into human breast milk in low concentrations. The milk-to-plasma (M/P) ratio is not established. Limited data suggest infant doses are small (likely <1% of maternal weight-adjusted dose). However, safety has not been established; monitor infant for adverse effects such as sedation, irritability, or poor feeding. In general, breastfeeding is not recommended during thiothixene therapy, especially in neonates or preterm infants, due to potential neurodevelopmental effects. Consider alternative agents with more safety data, or avoid breastfeeding. |
| Teratogenic Risk | Thiothixene is a typical antipsychotic (thioxanthene class). Data in pregnant women are limited. In animal studies, thiothixene has shown embryotoxicity and maternal toxicity at high doses. First trimester: Risk cannot be excluded; there is potential for congenital malformations, but absolute risk is low. Use only if benefit outweighs risk. Second and third trimesters: Exposure may increase risk for extrapyramidal symptoms (EPS) and/or withdrawal symptoms in neonates, including agitation, hypertonia, hypotonia, tremor, somnolence, respiratory distress, and feeding disorder. Neonates should be monitored. |
■ FDA Black Box Warning
Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Thiothixene is not approved for the treatment of dementia-related psychosis.
| Serious Effects |
["Hypersensitivity to thiothixene or any component of the formulation","Comatose states","CNS depression from alcohol, barbiturates, or other drugs","Blood dyscrasias (e.g., agranulocytosis)"]
| Precautions | ["Neuroleptic malignant syndrome (NMS)","Tardive dyskinesia","QT interval prolongation and risk of arrhythmias","Orthostatic hypotension","Seizure threshold lowering","Leukopenia/neutropenia/agranulocytosis"] |
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| Fetal Monitoring | During pregnancy: Monitor maternal blood pressure (especially for orthostatic hypotension), weight gain, blood glucose, and complete blood count. Assess for signs of EPS or tardive dyskinesia. Fetal monitoring: Serial fetal growth ultrasound (third trimester) and fetal heart rate monitoring (nonstress test) if clinically indicated (e.g., maternal complications). Neonate: Monitor for EPS, withdrawal symptoms (especially if third trimester exposure), and neurobehavioral adaptation after delivery. |
| Fertility Effects | Thiothixene, like other typical antipsychotics, can elevate serum prolactin levels via dopamine D2 receptor blockade in the pituitary. Hyperprolactinemia may suppress the hypothalamic-pituitary-gonadal axis, leading to menstrual irregularities, anovulation, and reduced fertility in females. In males, it may cause decreased libido, erectile dysfunction, or oligospermia. These effects are generally reversible upon dose reduction or discontinuation. |