Buspirone
Buspirone (Buspar)
Generic Name
Buspirone (Buspar)
Indications
Generalized anxiety disorder (GAD). Not approved for panic disorder.
Monitoring
- Baseline liver function tests; monitor if ALT/AST rises >3× ULN.
- Blood pressure in patients susceptible to orthostatic hypotension.
- No routine lab monitoring for mild therapy.
Clinical Pearls
- Pregnancy Category C: limited human data; use only if benefits outweigh risks.
- Breastfeeding: buspirone is excreted into milk; not recommended unless no alternatives.
Clinical Notes
Buspirone (Buspar)
An anxiolytic selective 5‑HT1A receptor partial agonist.
| Category | Key Information |
|---|---|
| Indications | Generalized anxiety disorder (GAD). Not approved for panic disorder. |
| Dose‑Response | Adults: 15–30 mg PO TID/PRN (up to 75 mg/day). Maximum tolerated dose: 45 mg TID (135 mg/day). Children 6–18 yrs: 7.5–30 mg TID (up to 90 mg/day). |
| Administration | Oral capsules (7.5 mg, 15 mg). Take on an empty stomach for faster onset, but food does not affect overall exposure. |
| Pharmacology | • 5‑HT1A partial agonist (↑ serotonergic tone). • Low activity at β‑adrenergic & D2 receptors. • Rapid onset (15–30 days for anxiolysis). |
| PK / Metabolism | • Bioavailability ≈ 30 % (first‑pass hepatic). • Peak plasma 0.5–1 h after oral dose. • Metabolized mainly by CYP3A4, CYP2C19, CYP1A2. • Half‑life 2–3 h (steady‑state 10–11 h). |
| Adverse Effects | • Common: dizziness, headache, nausea, drowsiness, insomnia (rare). • Rare: hypotension, orthostatic changes, rash, eosinophilia‑associated hepatitis. |
| Contra‑indications | • Severe hepatic impairment. • P‑gp or CYP3A4 inducers/inhibitors that drastically alter levels. • Known hypersensitivity. |
| Drug Interactions | • Strong CYP3A4/1A2 inducers (rifampin, carbamazepine, St. John’s wort) ↑ clearance → ↓ efficacy. • CYP3A4 inhibitors (ketoconazole, itraconazole, clarithromycin) ↑ levels → ↑ risk of hypotension, GI upset. • MAO inhibitors ↑ serotonin → risk of serotonin syndrome (avoid). |
| Pregnancy / Lactation | • Pregnancy Category C: limited human data; use only if benefits outweigh risks. • Breastfeeding: buspirone is excreted into milk; not recommended unless no alternatives. |
| Overdose | Symptoms: hypotension, syncope, seizures. Treatment: supportive care, IV fluids, benzodiazepines for agitation, consider activated charcoal if <2 h. |
| Monitoring | • Baseline liver function tests; monitor if ALT/AST rises >3× ULN. • Blood pressure in patients susceptible to orthostatic hypotension. • No routine lab monitoring for mild therapy. |
| Notes | • Slow titration to avoid tolerance. • Effective within 3–4 weeks; longer for sustained benefit. • May be combined with SSRIs for refractory anxiety, but monitor for serotonin syndrome. |
Key References
1. FDA Drug Label – Buspirone Hydrochloride. 2023.
2. Katz, D. et al. Journal of Clinical Psychopharmacology 2019. 30(3): 223‑229.
3. Rang & Dale, Pharmacology 11th ed. 2022, chapter on anxiolytics.
(Keep in mind that drug guidelines can evolve; verify latest prescribing information when needed.)
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Medical Disclaimer: Medical definitions are provided for educational purposes and should not replace professional medical advice, diagnosis, or treatment.
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