Pronunciation

(byoo SPYE rone)

Index Terms

• BuSpar
• Buspirone Hydrochloride

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Tablet, Oral, as hydrochloride:

Generic: 5 mg, 7.5 mg, 10 mg, 15 mg, 30 mg

Pharmacologic Category

• Antianxiety Agent, Miscellaneous

Pharmacology

The mechanism of action of buspirone is unknown. Buspirone has a high affinity for serotonin 5-HT_1A and 5-HT₂ receptors, without affecting benzodiazepine-GABA receptors. Buspirone has moderate affinity for dopamine D₂ receptors.

Absorption

Rapid and complete; bioavailability is limited by extensive first-pass effect; only 1.5% to 13% (mean 4%) of the oral dose reaches the systemic circulation unchanged

Distribution

V_d: 5.3 L/kg

Metabolism

Hepatic oxidation, primarily via CYP3A4 to several metabolites including an active metabolite, 1-pyrimidinylpiperazine (1-PP; exhibits about 25% of the activity of buspirone); extensive first-pass effect

Excretion

Urine: 29% to 63% (primarily as metabolites); feces: 18% to 38%

Onset of Action

Within 2 weeks

Time to Peak

Serum: 40 to 90 minutes

Half-Life Elimination

2 to 3 hours; increased with renal or hepatic impairment

Protein Binding

86%

Special Populations: Renal Function Impairment

AUC increased 4-fold.

Special Populations: Hepatic Function Impairment

AUC increased 13-fold.

Use: Labeled Indications

Management of generalized anxiety disorder (GAD)

Use: Unlabeled

Augmentation agent for antidepressants

Contraindications

Hypersensitivity to buspirone or any component of the formulation

Dosing: Adult

Generalized anxiety disorder (GAD): Oral: Initial: 7.5 mg twice daily; may increase every 2-3 days in increments of 2.5 mg twice daily to a maximum of 30 mg twice daily; a dose of 10-15 mg twice daily was most often used in clinical trials that allowed for dose titration

Augmentation agent for antidepressants (off-label use): Oral: Initial: 7.5 mg twice daily; may increase weekly in increments of 7.5 mg twice daily to a maximum of 30 mg twice daily (Trivedi, 2006).

Dosing: Geriatric

Refer to adult dosing.

Dosing: Renal Impairment

Patients with impaired renal function demonstrated increased plasma levels and a prolonged half-life of buspirone. Use in patients with severe renal impairment not recommended.

Dosing: Hepatic Impairment

Patients with impaired hepatic function demonstrated increased plasma levels and a prolonged half-life of buspirone. Use in patients with severe hepatic impairment not recommended.

Administration

May be administered with or without food, but must be consistent.

Dietary Considerations

May be taken with or without food, but must be consistent. Avoid large quantities of grapefruit juice.

Storage

Store at 25°C (77°F); excursions permitted between 15°C to 30°C (59°F to 86°F). Protect from light.

Drug Interactions

Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy

Analgesics (Opioid): May enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Monitor therapy

Antidepressants (Serotonin Reuptake Inhibitor/Antagonist): BusPIRone may enhance the serotonergic effect of Antidepressants (Serotonin Reuptake Inhibitor/Antagonist). Management: The combination of a serotonin reuptake inhibitor,antagonist and buspirone should be undertaken with great caution. When combined treatment is clinically indicated, monitor closely for signs of serotonin toxicity/serotonin syndrome. Consider therapy modification

Antiemetics (5HT3 Antagonists): May enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Monitor therapy

Antifungal Agents (Azole Derivatives, Systemic): May decrease the metabolism of BusPIRone. Isavuconazonium considerations are addressed in separate monographs. Exceptions: Isavuconazonium Sulfate. Consider therapy modification

Antipsychotic Agents: Serotonin Modulators may enhance the adverse/toxic effect of Antipsychotic Agents. Specifically, serotonin modulators may enhance dopamine blockade, possibly increasing the risk for neuroleptic malignant syndrome. Antipsychotic Agents may enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Monitor therapy

Aprepitant: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification

Bosentan: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine patches (Butrans brand) at 5 mcg/hr in adults when used with other CNS depressants. Consider therapy modification

Calcium Channel Blockers (Nondihydropyridine): May decrease the metabolism of BusPIRone. Exceptions: Bepridil. Consider therapy modification

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Monitor therapy

Conivaptan: May increase the serum concentration of CYP3A4 Substrates. Avoid combination

CYP3A4 Inducers (Moderate): May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

CYP3A4 Inducers (Strong): May increase the metabolism of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

CYP3A4 Inhibitors (Moderate): May decrease the metabolism of CYP3A4 Substrates. Monitor therapy

CYP3A4 Inhibitors (Strong): May decrease the metabolism of CYP3A4 Substrates. Consider therapy modification

Dabrafenib: May decrease the serum concentration of CYP3A4 Substrates. Management: Seek alternatives to the CYP3A4 substrate when possible. If concomitant therapy cannot be avoided, monitor clinical effects of the substrate closely (particularly therapeutic effects). Consider therapy modification

Dapoxetine: May enhance the adverse/toxic effect of Serotonin Modulators. Avoid combination

Dasatinib: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Deferasirox: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Dimethindene: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (e.g., opioids, barbiturates) with concomitant use. Consider therapy modification

Enzalutamide: May decrease the serum concentration of CYP3A4 Substrates. Management: Concurrent use of enzalutamide with CYP3A4 substrates that have a narrow therapeutic index should be avoided. Use of enzalutamide and any other CYP3A4 substrate should be performed with caution and close monitoring. Consider therapy modification

Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification

Fosaprepitant: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Fusidic Acid (Systemic): May increase the serum concentration of CYP3A4 Substrates. Avoid combination

Grapefruit Juice: May decrease the metabolism of BusPIRone. Consider therapy modification

HYDROcodone: CNS Depressants may enhance the CNS depressant effect of HYDROcodone. Management: Consider starting with a 20% to 30% lower hydrocodone dose when using together with any other CNS depressant. Dose reductions in the other CNS depressant may also be warranted. Consider therapy modification

HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Idelalisib: May increase the serum concentration of CYP3A4 Substrates. Avoid combination

Ioflupane I 123: BusPIRone may diminish the diagnostic effect of Ioflupane I 123. Monitor therapy

Ivacaftor: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Luliconazole: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Macrolide Antibiotics: May decrease the metabolism of BusPIRone. Exceptions: Azithromycin (Systemic); Fidaxomicin; Roxithromycin; Spiramycin. Consider therapy modification

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

MAO Inhibitors: BusPIRone may enhance the adverse/toxic effect of MAO Inhibitors. Specifically, blood pressure elevations been reported. Avoid combination

Metaxalone: May enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Monitor therapy

Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification

Methylene Blue: BusPIRone may enhance the serotonergic effect of Methylene Blue. This could result in serotonin syndrome. Avoid combination

Metoclopramide: Serotonin Modulators may enhance the adverse/toxic effect of Metoclopramide. This may be manifest as symptoms consistent with serotonin syndrome or neuroleptic malignant syndrome. Monitor therapy

MetyroSINE: CNS Depressants may enhance the sedative effect of MetyroSINE. Monitor therapy

MiFEPRIStone: May increase the serum concentration of CYP3A4 Substrates. Management: Minimize doses of CYP3A4 substrates, and monitor for increased concentrations/toxicity, during and 2 weeks following treatment with mifepristone. Avoid cyclosporine, dihydroergotamine, ergotamine, fentanyl, pimozide, quinidine, sirolimus, and tacrolimus. Consider therapy modification

Minocycline: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirtazapine: CNS Depressants may enhance the CNS depressant effect of Mirtazapine. Monitor therapy

Mitotane: May decrease the serum concentration of CYP3A4 Substrates. Management: Doses of CYP3A4 substrates may need to be adjusted substantially when used in patients being treated with mitotane. Consider therapy modification

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Netupitant: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination

OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: When oxycodone is combined with another CNS depressant, a dose reduction of one or both agents should be considered. The extended release oxycodone starting dose should be reduced 50% to 67% when initiated in patients already receiving CNS depressants. Consider therapy modification

Palbociclib: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification

Piribedil [INT]: CNS Depressants may enhance the CNS depressant effect of Piribedil [INT]. Monitor therapy

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

Resveratrol: May increase the serum concentration of BusPIRone. Monitor therapy

Rifamycin Derivatives: May decrease the serum concentration of BusPIRone. Management: The degree to which rifampin alters buspirone concentrations warrants the consideration of an alternative to buspirone that is not metabolized by CYP3A4. If these agents are used together, buspirone dose adjustments may be needed. Consider therapy modification

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Selective Serotonin Reuptake Inhibitors: BusPIRone may enhance the serotonergic effect of Selective Serotonin Reuptake Inhibitors. This may cause serotonin syndrome. Selective Serotonin Reuptake Inhibitors may decrease the metabolism of BusPIRone. Management: The combination of a selective serotonin reuptake inhibitor and buspirone should be undertaken with great caution. When combined treatment is clinically indicated, monitor closely for signs of serotonin toxicity/serotonin syndrome. Consider therapy modification

Serotonin Modulators: May enhance the adverse/toxic effect of other Serotonin Modulators. The development of serotonin syndrome may occur. Exceptions: Nicergoline; Tedizolid. Monitor therapy

Siltuximab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

Simeprevir: May increase the serum concentration of CYP3A4 Substrates. Monitor therapy

Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification

St John's Wort: May decrease the serum concentration of CYP3A4 Substrates. Management: Consider an alternative for one of the interacting drugs. Some combinations may be specifically contraindicated. Consult appropriate manufacturer labeling. Consider therapy modification

Stiripentol: May increase the serum concentration of CYP3A4 Substrates. Management: Use of stiripentol with CYP3A4 substrates that are considered to have a narrow therapeutic index should be avoided due to the increased risk for adverse effects and toxicity. Any CYP3A4 substrate used with stiripentol requires closer monitoring. Consider therapy modification

Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification

Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Start tapentadol at a dose of one-third to one-half of the normal dose if being initiated in a patient who is taking another drug with CNS depressant effects. Monitor closely for evidence of excessive CNS depression. Consider therapy modification

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Tocilizumab: May decrease the serum concentration of CYP3A4 Substrates. Monitor therapy

TraMADol: Serotonin Modulators may enhance the adverse/toxic effect of TraMADol. The risk of seizures may be increased. TraMADol may enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Monitor therapy

Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Yohimbine: May diminish the therapeutic effect of Antianxiety Agents. Monitor therapy

Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification

Test Interactions

The presence of buspirone may result in a false positive on a urinary assay for metanephrine/catecholamine; discontinue buspirone ≥48 hours prior to collection of urine sample for catecholamines

Adverse Reactions

>10%: Central nervous system: Dizziness (3% to 12%)

1% to 10%:

Cardiovascular: Chest pain (≥1%)

Central nervous system: Drowsiness (10%), headache (6%), nervousness (5%), confusion (2%), excitement (2%), numbness (2%), outbursts of anger (2%), abnormal dreams (≥1%), ataxia (1%) paresthesia (1%)

Dermatologic: Diaphoresis (1%), skin rash (1%)

Gastrointestinal: Nausea (8%), diarrhea (2%), sore throat (≥1%)

Neuromuscular & skeletal: Weakness (2%), musculoskeletal pain (1%), tremor (1%)

Ophthalmic: Blurred vision (2%)

Otic: Tinnitus (≥1%)

Respiratory: Nasal congestion (≥1%)

<1% (Limited to important or life-threatening): Alcohol abuse, alopecia, amenorrhea, angioedema, anorexia, bradycardia, bruise, cardiac failure, cardiomyopathy, cerebrovascular accident, claustrophobia, cogwheel rigidity, conjunctivitis, dyskinesia, dystonia, edema, eosinophilia, epistaxis, extrapyramidal reaction, galactorrhea, hallucination, hemorrhagic diathesis, hypersensitivity reaction, hypertension, hyperventilation, hypotension, increased intraocular pressure, increased serum ALT, increased serum AST, increased serum transaminases, irritable bowel syndrome, leukopenia, memory impairment, menstrual disease, myocardial infarction, parkinsonian-like syndrome, pelvic inflammatory disease, personality disorder, photophobia, psychosis, rectal hemorrhage, restless leg syndrome, seizure, serotonin syndrome, slowed reaction time, slurred speech, suicidal ideation, syncope, thrombocytopenia, thyroid disease, urinary incontinence, visual disturbance (tunnel vision)

Warnings/Precautions

Concerns related to adverse effects:

• Cognitive/motor impairment: Low potential for cognitive or motor impairment; until effects on patient known, patients should be warned to use caution when performing tasks which require mental alertness (eg, operating machinery or driving).

• Restlessness syndrome: Has been reported in small number of patients; may be attributable to buspirone’s antagonism of central dopamine receptors. Monitor for signs of any dopamine-related movement disorders (eg, dystonia, akathisia, pseudo-parkinsonism)

Disease-related concerns:

• Hepatic impairment: Use in patients with severe hepatic impairment is not recommended.

• Renal impairment: Use in patients with severe renal impairment is not recommended.

Concurrent drug therapy issues:

• MAO inhibitors: Use with MAO inhibitors may result in hypertensive reactions; concurrent use is not recommended.

• Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.

Other warnings/precautions:

• Sedative/hypnotic withdrawal: Buspirone does not exhibit cross-tolerance with benzodiazepines or other sedative/hypnotic agents. If substituting buspirone for any of these agents, gradually withdraw the drug(s) prior to initiating buspirone.

Monitoring Parameters

Mental status, symptoms of anxiety

Pregnancy Risk Factor

B

Pregnancy Considerations

Adverse events have not been observed in animal reproduction studies.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)

• Patient may experience fatigue, anxiety, headache, or nausea. Have patient report immediately to prescriber severe dizziness, passing out, depression, confusion, tachycardia, abnormal heartbeat, agitation, abnormal movements, twitching, change in balance, difficulty speaking, difficulty swallowing, or vision changes (HCAHPS).

• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for health care professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience, and judgment in diagnosing, treating, and advising patients.