busPIRone, BuSpar

 Indications

Management of anxiety.

Action

Binds to serotonin and dopamine receptors in the

brain. Increases norepinephrine metabolism in the

brain. Therapeutic Effects: Relief of anxiety.

Pharmacokinetics

Absorption: Rapidly absorbed.

Distribution: Unknown.

Protein Binding: 95% bound to plasma proteins.

Metabolism and Excretion: Extensively metabolized

by the liver (CYP3A4 enzyme system); 20–40%

excreted in feces.

Half-life: 2–3 hr.

TIME/ACTION PROFILE (relief of anxiety)

ROUTE ONSET PEAK DURATION

PO 7–10 days 3–4 wk unknown

Contraindications/Precautions

Contraindicated in: Hypersensitivity; Severe hepatic

or renal impairment; Concurrent use of MAO inhibitors;

Ingestion of large amounts of grapefruit juice.

Use Cautiously in: Patients receiving other antianxiety

agents (other agents should be slowly withdrawn to

prevent withdrawal or rebound phenomenon); Patients

receiving other psychotropics; Lactation, OB, Pedi:

Safety not established.

Adverse Reactions/Side Effects

CNS: dizziness, drowsiness, excitement, fatigue, headache,

insomnia, nervousness, weakness, personality

changes. EENT: blurred vision, nasal congestion, sore

throat, tinnitus, altered taste or smell, conjunctivitis.

Resp: chest congestion, hyperventilation, shortness of

breath. CV: chest pain, palpitations, tachycardia, hypertension,

hypotension, syncope. GI: nausea, abdominal

pain, constipation, diarrhea, dry mouth, vomiting.

GU: changes in libido, dysuria, urinary frequency, urinary

hesitancy. Derm: rashes, alopecia, blisters, dry

skin, easy bruising, edema, flushing, pruritus. Endo:

irregular menses. MS: myalgia. Neuro: incoordination,

numbness, paresthesia, tremor. Misc: clamminess,

sweating, fever.

Interactions

Drug-Drug: Use with MAO inhibitors may result in

hypertension and is not recommended. Erythromycin,

nefazodone, ketoconazole, itraconazole, ritonavir,

and other inhibitors of CYP3A4qblood levels

and effects of buspirone; dose reduction is recommended

(pto 2.5 mg twice daily with erythromycin;p

to 2.5 mg once daily with nefazodone). Rifampin,

dexamethasone, phenytoin, phenobarbital, carbamazepine,

and other inducers of CYP3A4p

blood levels and effects of buspirone; dose adjustment

may be necessary. Avoid concurrent use with alcohol.

Drug-Natural Products: Concomitant use of

kava-kava, valerian, or chamomile canqCNS depression.

Drug-Food: Grapefruit juiceqserum levels and

effect; ingestion of large amounts of grapefruit juice is

not recommended.

Route/Dosage

PO (Adults): 7.5 mg twice daily;qby 5 mg/day q 2–4

days as needed (not to exceed 60 mg/day). Usual dose

is 20–30 mg/day (in 2 divided doses).

Availability (generic available)

Tablets: 5 mg, 7.5 mg, 10 mg, 15 mg, 30 mg. Cost:

Generic—5 mg $77.12/100, 7.5 mg $109.08/100, 10

mg $134.50/100, 15 mg $201.92/100, 30 mg $218.10/

100.