Buspirone


Concise Prescribing Info
Indications/Uses
Anxiety.
Dosage/Direction for Use
Adult : PO Initial: 5 mg bid or tid, increased gradually if needed. Max: 60 mg/day.
Dosage Details
Oral
Short-term management of anxiety
Adult: Initially, 5 mg bid or tid, gradually increase by increments of 5 mg at 2-3 days interval. Usual dose: 15-30 mg daily in divided doses. Max: 60 mg daily.
Special Patient Group
Patients taking potent CYP3A4 enzyme inhibitors: Initially, 2.5 mg once daily or bid, adjust based on clinical assessment.
Renal Impairment
CrCl (mL/min) Dosage
<20 Contraindicated.
20-49  Initially, 5 mg bid. 
Hepatic Impairment
Severe: Contraindicated.
Administration
May be taken with or without food. Take consistently either always w/ or always w/o meals.
Contraindications
Epilepsy. Concomitant use w/ MAOIs. Severe renal (CrCl <20 mL/min) or hepatic impairment. Lactation.
Special Precautions
Patient w/ acute narrow-angle glaucoma, myasthenia gravis, drug dependence. Renal or hepatic impairment.
Adverse Reactions
Nervousness, insomnia, disturbance in attention, depression, confusion, seizure, sleep disorder; dizziness, headache, light-headedness, excitement, somnolence, paraesthesia, blurred vision, coordination disorder, tremor, tinnitus; tachycardia, palpitation, chest pain; nasal congestion, pharyngolaryngeal pain; nausea, abdominal pain, dry mouth, diarrhoea, constipation, vomiting; cold sweat, rash, musculoskeletal pain, fatigue. Rarely, angioneurotic oedema, ecchymosis, urticaria.
Patient Counseling Information
This drug may cause sedation and dizziness, if affected, do not drive or operate machinery.
MonitoringParameters
Monitor mental status.
Overdosage
Symptoms: Nausea, vomiting, dizziness, drowsiness, miosis, gastric distress, mild bradycardia, hypotension, extrapyramidal symptoms, and convulsions. Management: Symptomatic and supportive treatment w/ immediate gastric lavage. May consider activated charcoal w/in 1 hr of ingestion of >5 mg/kg.
Drug Interactions
Increased serum concentration when used w/ CYP3A4 enzyme inhibitors (e.g. erythromycin, itraconazole, nefazodone, ritonavir, diltiazem, verapamil). Decreased metabolism and therapeutic effect when used w/ CYP3A4 enzyme inducers (e.g. rifampicin). Enhanced sedative effect w/ baclofen, lofexidine, nabilone, antihistamines. May increase serum concentration of haloperidol. Buspirone does not exhibit cross-tolerance w/ sedative/hypnotics (e.g. benzodiazepine) and will not block symptoms of their withdrawal, gradually withdraw such agents prior to initiation of buspirone.
Potentially Fatal: Increased BP when taken w/ MAOIs.
Food Interaction
Enhanced sedative effects w/ alcohol. Food may delay absorption and decrease first-pass metabolism, thereby increasing bioavailability. Grapefruit juice may increase buspirone concentration.
Lab Interference
May cause false-positive result on urinalysis for metanephrine/catecholamine.
Action
Description: Buspirone, an azaspirodecanedione, is an anxioselective drug w/ only little sedative effect but w/o anticonvulsant and muscle relaxant properties. It has high affinity for serotonin (5-HT1A and 5-HT2), moderate affinity for dopamine (D2), and no affinity for GABA receptors.
Onset: W/in 2 wk.
Pharmacokinetics:
Absorption: Rapidly and almost completely absorbed from the GI tract. Bioavailability: 1.5%-13%. Time to peak plasma concentration: W/in 40-90 min.
Distribution: Volume of distribution: 5.3 L/kg. Plasma protein binding: Approx 86%-95%, mainly to albumin.
Metabolism: Extensively metabolised in the liver by CYP3A4 enzyme via oxidative dealkylation to 1-pyrimidinylpiperazine as active metabolite and via hydroxylation to inactive metabolites; undergoes extensive first-pass metabolism.
Excretion: Via urine (approx 29-63%, mainly as metabolites); faeces (approx 18-38%). Elimination half-life: 2-3 hr.
Chemical Structure

Chemical Structure Image
Buspirone

Source: National Center for Biotechnology Information. PubChem Database. Buspirone, CID=2477, https://pubchem.ncbi.nlm.nih.gov/compound/Buspirone (accessed on Jan. 22, 2020)

Storage
Store between 15-30°C. Protect from light.
MIMS Class
ATC Classification
N05BE01 - buspirone ; Belongs to the class of azaspirodecanedione derivatives anxiolytics. Used in the management of anxiety, agitation or tension.
References
Anon. Buspirone. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 10/08/2016.

Buckingham R (ed). Buspirone Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 10/08/2016.

Buspirone Hydrochloride Tablet (Accord Healthcare Inc). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 10/08/2016.

Joint Formulary Committee. Buspirone Hydrochloride. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 10/08/2016.

McEvoy GK, Snow EK, Miller J et al (eds). Buspirone Hydrochloride. AHFS Drug Information (AHFS DI) [online]. American Society of Health-System Pharmacists (ASHP). https://www.medicinescomplete.com. Accessed 10/08/2016.

Disclaimer: This information is independently developed by MIMS based on Buspirone from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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