Buspirone Hydrochloride

Pronunciation: (byoo-SPY-rone HIGH-droe-KLOR-ide)Class: Antianxiety agent

Trade Names:BuSpar- Tablets 5 mg (4.6 mg as base)- Tablets 10 mg (9.1 mg as base)- Tablets 15 mg (13.7 mg as base)- Tablets 30 mg (27.4 mg as base)

Apo-Buspirone (Canada)CO Buspirone (Canada)Gen-Buspirone (Canada)PMS-Buspirone (Canada)ratio-Buspirone (Canada)

Pharmacology

Mechanism unknown; does not exert anticonvulsant or muscle relaxant effects.

Pharmacokinetics

Absorption

Rapidly absorbed. C _max is 1 to 6 mg/mL. T _max is 40 to 90 min.

Distribution

About 86% bound to plasma proteins.

Metabolism

Extensive first-pass metabolism. Primarily metabolized by oxidation (which is mediated by CYP3A4) to active metabolite.

Elimination

Within 24 h, 29% to 63% excreted in urine, primarily as metabolites; 18% to 38% is excreted in feces. The t _½ is about 2 to 3 h.

Special Populations

Renal Function Impairment

AUC increased 4-fold.

Hepatic Function Impairment

AUC increased 13-fold.

Indications and Usage

Treatment of anxiety disorders; short-term relief of anxiety symptoms.

Unlabeled Uses

Reduction of symptoms of PMS.

Contraindications

Standard considerations.

Dosage and Administration

Adults Initial dose

PO 7.5 mg twice daily; may increase by 5 mg/day every 2 to 3 days as needed (max, 60 mg/day in divided doses).

Storage/Stability

Store tablets below 86°F.

Drug Interactions

Diazepam

Dizziness, headache, and nausea can occur.

Fluoxetine

Buspirone effects may be decreased. Paradoxical worsening of obsessive-compulsive disorder (OCD) may occur.

Haloperidol

Buspirone may increase haloperidol plasma levels.

Inducers of CYP3A4 (eg, carbamazepine, dexamethasone, phenobarbital, phenytoin, rifampin)

May reduce buspirone plasma levels, decreasing the therapeutic effect.

Inhibitors of CYP3A4 (eg, diltiazem, erythromycin, grapefruit juice, itraconazole, ketoconazole, nefazodone, ritonavir, verapamil)

May elevate buspirone plasma levels, increasing the pharmacologic and adverse effects.

MAOIs (eg, isocarboxazid)

Risk of elevated BP may be increased. Do not administer buspirone with or within 14 days of MAOI administration.

Nefazodone

If used with buspirone, a low dose (eg, 2.5 mg/day) is recommended.

Trazodone

ALT may be elevated.

Laboratory Test Interactions

None well documented.

Adverse Reactions

Cardiovascular

Chest pain (at least 1%); tachycardia/palpitations (1%).

CNS

Dizziness (12%); drowsiness (10%); headache (6%); nervousness (5%); lightheadedness (3%); excitement, numbness, anger/hostility, confusion, weakness (2%); paresthesia, incoordination, tremor (1%); dream disturbances (at least 1%); cogwheel rigidity, dizziness, dystonic reactions, ataxia, extrapyramidal effects, dyskinesias (acute and tardive), emotional lability, serotonin syndrome, difficulty in recall (postmarketing).

Dermatologic

Skin rash, sweating/clamminess (1%); ecchymosis (postmarketing).

EENT

Blurred vision (2%); tinnitus, sore throat, nasal congestion (at least 1%); visual changes (postmarketing).

GI

Nausea (8%); diarrhea (2%).

Genitourinary

Urinary retention (postmarketing).

Musculoskeletal

Aches/pains (1%).

Miscellaneous

Allergic reactions (including urticaria), angioedema (postmarketing).

Precautions

Pregnancy

Category B .

Lactation

Undetermined. Breast-feeding should be avoided.

Children

The safety and efficacy of buspirone were evaluated in 2 placebo-controlled, 6-wk trials involving a total of 559 pediatric patients (ranging from 6 to 17 yr of age) with generalized anxiety disorder (GAD). Doses studied were 7.5 to 30 mg twice daily (15 to 60 mg/day). There were no significant differences between buspirone and placebo with regard to the symptoms of GAD following doses recommended for the treatment of GAD in adults. Pharmacokinetic studies have shown that, for identical doses, plasma exposure to buspirone and its active metabolite, 1-PP, are equal to or higher in pediatric patients than adults. No unexpected safety findings were associated with buspirone in these trials. There are no long-term safety or efficacy data in this population.

Renal Function

Administration of buspirone not recommended.

Hepatic Function

Administration of buspirone not recommended.

Overdosage

Symptoms

Nausea, vomiting, dizziness, drowsiness, miosis, gastric distress.

Patient Information

• Advise patient or caregiver to read the patient information leaflet before starting therapy and with each refill.
• Advise patient that medication is usually started at a low dose and then gradually increased until max benefit is obtained.
• Advise patient that medication must be taken daily as prescribed in order to obtain max benefit and not to use on an as needed basis.
• Advise patient to take each dose consistently either with or without food.
• Caution patient to avoid grapefruit and grapefruit juice while taking this medication.
• Caution patient to take as prescribed and not to stop taking or change the dose unless advised by health care provider.
• Advise patient that if a dose is missed to skip that dose and take the next dose at the regularly scheduled time. Caution patient to never take 2 doses at the same time.
• Instruct patient to avoid alcoholic beverages and other depressants while taking this medication.
• Instruct patient to contact health care provider if symptoms do not appear to be getting better, are getting worse, or if bothersome side effects (eg, drowsiness, dizziness) occur.
• Advise patient that drug may cause drowsiness or dizziness and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.

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