LOXAPINE SUCCINATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LOXAPINE SUCCINATE (LOXAPINE SUCCINATE).
Loxapine is a dibenzoxazepine antipsychotic that exerts its effects primarily through antagonism of dopamine D2 and serotonin 5-HT2A receptors. It also has moderate affinity for histamine H1, alpha-1 adrenergic, and muscarinic acetylcholine receptors.
| Metabolism | Primarily hepatic via CYP1A2, CYP3A4, and CYP2D6. Major metabolites include 8-hydroxyloxapine and N-desmethyl derivatives, with some activity. |
| Excretion | Renal (approximately 60% as metabolites, <1% unchanged) and fecal (approximately 40% as metabolites). |
| Half-life | Terminal elimination half-life: 12–19 hours (mean 16 hours) after oral administration; steady-state reached within 3–5 days. |
| Protein binding | Approximately 96-98% bound, primarily to alpha-1-acid glycoprotein and albumin. |
| Volume of Distribution | Vd: 0.9–1.2 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral: 33% (due to extensive first-pass metabolism); intramuscular: 100% (relative to oral). |
| Onset of Action | Oral: 20–30 minutes; intramuscular: 10–15 minutes. |
| Duration of Action | Oral: 8–12 hours; intramuscular: 12–24 hours. |
| Molecular Weight | 327.82 |
Initial: 10 mg twice daily orally; increase to 25-50 mg twice daily over 7-10 days; maximum 250 mg/day. IM: 12.5-50 mg every 4-6 hours.
| Dosage form | CAPSULE |
| Renal impairment | CrCl 50-80 mL/min: 75% of normal dose. CrCl 10-50 mL/min: 50% of normal dose. CrCl <10 mL/min: 25% of normal dose. |
| Liver impairment | Child-Pugh Class A: 50% of normal dose. Child-Pugh Class B: 25% of normal dose. Child-Pugh Class C: contraindicated. |
| Pediatric use | Adolescents (12-18 years): Initial 10 mg/day orally, titrate gradually; maximum 150 mg/day. Children <12 years: not recommended. |
| Geriatric use | Initial 5-10 mg/day orally; increase slowly by 5-10 mg increments; maximum 150 mg/day. Increased sensitivity to extrapyramidal symptoms and hypotension. |
| 1st trimester | Limited human data; animal studies show fetal harm. Use only if potential benefit justifies risk. Consider antipsychotic with more safety data if possible. |
| 2nd trimester | Limited human data; may cause extrapyramidal symptoms or withdrawal in neonate if used late in pregnancy. Use only if clearly needed. |
| 3rd trimester | May cause neonatal extrapyramidal symptoms, agitation, or withdrawal. Avoid in third trimester unless essential. Monitor newborn for symptoms. |
Clinical note
Comprehensive clinical and safety monograph for LOXAPINE SUCCINATE (LOXAPINE SUCCINATE).
| Placental transfer | Loxapine crosses the placenta; animal studies and some human data demonstrate transfer. Degree of transfer is moderate, with fetal concentrations possibly lower than maternal. |
| Breastfeeding | Loxapine is excreted into breast milk; relative infant dose is estimated at 0.5–2% of weight-adjusted maternal dose. Monitor infant for sedation, irritability, or poor feeding. Usually compatible with breastfeeding if clinically necessary, but consider alternative agents with more safety data. |
■ FDA Black Box Warning
Increased mortality in elderly patients with dementia-related psychosis. Loxapine is not approved for the treatment of dementia-related psychosis.
| Common Effects | Allergic reaction Application site reactions burning irritation itching and redness |
| Serious Effects |
Hypersensitivity to loxapine or any componentSevere central nervous system depressionComatose states
| Precautions | Neuroleptic malignant syndrome (NMS), Tardive dyskinesia (TD), QT prolongation, Seizures (lower threshold), Orthostatic hypotension, Hyperprolactinemia, Leukopenia/neutropenia/agranulocytosis, Similar to other antipsychotics: potential for venous thromboembolism |
| Food/Dietary | No significant food interactions. Avoid excessive caffeine or grapefruit juice as they may alter metabolism. Maintain adequate hydration. |
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| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Limited data; animal studies show no clear teratogenicity but risk cannot be excluded. Second/third trimester: Neonatal extrapyramidal symptoms and withdrawal (e.g., agitation, hypertonia) if used near term. Overall: FDA Pregnancy Category C (pre-2015); use only if benefit outweighs risk. |
| Fetal Monitoring | Monitor maternal blood pressure, glucose, weight, and EPS. Fetal: Ultrasound for growth and anatomy. Neonatal: Observe for EPS, withdrawal, and sedation post-delivery. |
| Fertility Effects | May elevate prolactin levels causing galactorrhea, amenorrhea, and transient infertility. No direct evidence of permanent fertility impairment. |
| Clinical Pearls | Loxapine succinate is a first-generation antipsychotic with high potency, often used for acute agitation in schizophrenia. Monitor for extrapyramidal symptoms (EPS), especially in younger patients, and for orthostatic hypotension. Its active metabolite, amoxapine, has antidepressant properties. Avoid in patients with severe CNS depression or bone marrow suppression. |
| Patient Advice | Take this medication exactly as prescribed. Do not stop abruptly. · Avoid alcohol and other CNS depressants (e.g., benzodiazepines, opioids). · Rise slowly from sitting or lying to prevent dizziness. · Report any involuntary muscle movements, stiffness, or fever immediately. · May cause drowsiness; avoid driving until you know how it affects you. · Drink plenty of water to prevent constipation. · Monitor for weight gain and report any unusual changes. · Store at room temperature away from moisture and heat. |