Buspirone, BuSpar Pharmacology

Buspirone

Brand Name: BuSpar

Outside U.S., Brand Names also known as: Ansial; Ansiced; Ansitec; Anxinil; Anxiolan; Barpil; Bespar; Biron; Busirone; Buspirone; Kallmiren; Narol; Nerbet; Neurosine; Normaton; Paxon; Relac; Sburol; Tutran

Contents:

Description
Pharmacology
Indications and Usage
Contraindications
Warnings
Precautions
Drug Interactions
Adverse Reactions
Overdose
Dosage
Supplied

Buspar patient information (in plain English)

Description

Buspirone (BuSpar) is used for the treatment of nervousness and anxiety.

BuSpar (buspirone hydrochloride) is an antianxiety agent that is not chemically or pharmacologically related to the benzodiazepines, barbiturates, or other sedative/anxiolytic drugs. It is a psychotropic drug with anxiolytic properties which belongs chemically to the class of compounds known as the azaspirodecanediones.

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Pharmacology

The mechanism of action of buspirone is unknown. Buspirone differs from typical benzodiazepine anxiolytics in that it does not exert anticonvulsant or muscle relaxant effects. It also lacks the prominent sedative effect that is associated with more typical anxiolytics.

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Indications and Usage

Buspirone is indicated for the management of anxiety disorders or the short-term relief of the symptoms of anxiety. Anxiety or tension associated with the stress of everyday life usually does not require treatment with an anxiolytic.

The efficacy of buspirone has been demonstrated in controlled clinical trials of outpatients whose diagnosis roughly corresponds to Generalized Anxiety Disorder (GAD). Many of the patients enrolled in these studies also had coexisting depressive symptoms and buspirone relieved anxiety in the presence of these coexisting depressive symptoms. The patients evaluated in these studies had experienced symptoms for periods of 1 month to over 1 year prior to the study, with an average symptom duration of 6 months.

The effectiveness of buspirone in long-term use, that is, for more than 3 to 4 weeks, has not been demonstrated in controlled trials. There is no body of evidence available that systematically addresses the appropriate duration of treatment for GAD. However, in a study of long-term use, 264 patients were treated with buspirone for 1 year without ill effect. Therefore, the physician who elects to use buspirone for extended periods should periodically reassess the usefulness of the drug for the individual patient.

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Contraindications

Buspirone is contraindicated in patients hypersensitive to buspirone hydrochloride.

Buspirone is contraindicated in patients with severe hepatic or severe renal impairment.

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Warnings

The administration of buspirone HCl to a patient taking a monoamine oxidase inhibitor (MAOI) may pose a hazard.There have been reports of the occurrence of elevated blood pressure when buspirone has been added to a regimen including an MAOI. Therefore, it is recommended that buspirone not be used concomitantly with an MAOI.

Because buspirone has no established antipsychotic activity, it should not be employed in lieu of appropriate antipsychotic treatment.

Since the effects of buspirone have not been evaluated in patients with a history of convulsive disorders and since it lacks anticonvulsant activity in animals, buspirone is not recommended for patients with seizure disorders.

Use of Buspirone in Patients Previously Treated with a Benzodiazepine:
Patients who have previously taken benzodiazepines may be less likely to respond to buspirone than those who have not. In 2 clinical studies to date, substitution of buspirone did not ameliorate or prevent withdrawal symptoms in either abrupt or gradual withdrawal from various benzodiazepines following long-term use. Therefore, if it is considered desirable to switch a patient who has been receiving benzodiazepine therapy to buspirone, the benzodiazepine should first be withdrawn gradually. A drug-free interval is desirable between withdrawal of the benzodiazepine and initiation of buspirone, in order to increase the likelihood of distinguishing between benzodiazepine withdrawal effects and unrelieved anxiety due to possible failure of buspirone in this category of patients.

Dependence & Withdrawl: Benzodiazepine rebound or withdrawal symptoms may occur over varying time periods depending in part on the type of drug and its effective half-life of elimination. These symptoms may appear as any combination of irritability, anxiety, agitation, insomnia, tremor, abdominal cramps, muscle cramps, vomiting, sweating, flu-like symptoms without fever and, occasionally, seizures, and should be treated symptomatically.

Usage in Pregnancy & Nursing

The safety of buspirone during pregnancy and lactation has not been established and, therefore, it should not be used in women of childbearing potential or nursing mothers, unless, in the opinion of the physician, the potential benefits to the patient outweigh the possible hazards to the fetus. Buspirone and its metabolites are excreted in milk in rats. The extent of excretion in human milk has not yet been determined.

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Precautions

Interference with cognitive and motor performance: Studies indicate that buspirone is less sedating than other anxiolytics and that it does not produce significant functional impairment. However, its CNS effects in any individual patient may not be predictable. Therefore, patients should be cautioned about operating an automobile or using complex machinery until they are reasonably certain that buspirone treatment does not affect them adversely.

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Possible concerns related to buspirone's binding to dopamine receptors: Because buspirone can bind to central dopamine receptors, a question has been raised about its potential to cause acute and chronic changes in dopamine-mediated neurological function (e.g., dystonia, pseudo-parkinsonism, akathisia, and tardive dyskinesia). Clinical experience in controlled trials has failed to identify any significant neuroleptic-like activity; however, a syndrome of restlessness, appearing shortly after initiation of treatment, has been reported in some small fraction of buspirone-treated patients. The syndrome may be explained in several ways. For example, buspirone may increase central noradrenergic activity; alternatively, the effect may be attributable to dopaminergic effects (i.e., represent akathisia). Obviously, the question cannot be totally resolved at this point in time. Generally, long-term sequelae of any drug's use can be identified only after several years of marketing.

Pediatric Use
The safety and effectiveness of buspirone have not been determined in individuals below 18 years of age.

Elderly: Buspirone has not been systematically evaluated in older patients. Although it would appear from limited pharmacokinetic and clinical studies that buspirone does not behave differently in the elderly, there is little known about the effects of buspirone in this age group at doses above 30 mg/day. Therefore, it is recommended that buspirone should be used in the elderly at doses not exceeding 30 mg/day for a duration not exceeding 4 weeks.

Use In Patients with Impaired Hepatic or Renal Function:
Since buspirone is metabolized by the liver and excreted by the kidneys, its administration to patients with severe hepatic or renal impairment cannot be recommended.

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Drug Interactions

It is recommended that buspirone hydrochloride not be used concomitantly with MAO inhibitors. Because the effects of concomitant administration of buspirone with most other psychotropic drugs have not been studied, the concomitant use of buspirone with other CNS-active drugs should be approached with caution.

In a study in normal volunteers, concomitant administration of buspirone and haloperidol resulted in increased serum haloperidol concentrations. The clinical significance of this finding is not clear.

BEFORE USING THIS MEDICINE: Some medicines or medical conditions may interact with this medicine. INFORM YOUR DOCTOR OR PHARMACIST of all prescription and over-the-counter medicine that you are taking. Additional monitoring of your dose or condition may be needed if you are taking fluconazole, itraconazole, ketoconazole, or macrolide antibiotics. Inform your doctor of any other medical conditions, allergies, pregnancy, or breast-feeding. Contact your doctor or pharmacist if you have any questions or concerns about taking this medicine.

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Adverse Reactions

Cardiovascular: Frequent was nonspecific chest pain; infrequent were syncope, hypotension, and hypertension; rare were cerebrovascular accident, congestive heart failure, myocardial infarction, cardiomyopathy, and bradycardia.

Central Nervous System Effects: Frequent were dream disturbances; infrequent were depersonalization, dysphoria, noise intolerance, euphoria, akathisia, fearfulness, loss of interest, dissociative reaction, hallucinations, suicidal ideation, and seizures; rare were feelings of claustrophobia, cold intolerance, stupor, and slurred speech and psychosis.

EENT: Frequent were tinnitus, sore throat, and nasal congestion; infrequent were redness and itching of the eyes, altered taste, altered smell, and conjunctivitis; rare were inner ear abnormality, eye pain, photophobia, and pressure on eyes.

Endocrine: Rare were galactorrhea and thyroid abnormality. photosensitization, and pruritus have occasionally occurred.

Gastrointestinal: Infrequent were flatulence, anorexia, increased appetite, salivation, irritable colon, and rectal bleeding; rare was burning of the tong

Genitourinary: Infrequent were urinary frequency, urinary hesitancy, menstrual irregularity and spotting, and dysuria; rare were amenorrhea, pelvic inflammatory disease, enuresis, and nocturia.

Musculoskeletal: Infrequent were muscle cramps, muscle spasms, rigid/stiff muscles, and arthralgias.

Sexual Function: Infrequent were decreased or increased libido; rare were delayed ejaculation and impotence.

Miscellaneous: Tinnitus, muscle aches/pains. Infrequently, redness/itching of eyes, altered taste/smell, roaring sensation in head, malaise, easy bruising, dry skin, arthralgia, blisters, hair loss. Rarely, acne, thinning of nails, sore eyes, inner ear abnormality, pressure on eyes, nocturia, enuresis, hiccups, voice loss, alcohol abuse.

Post Introduction Clinical Experience: Post-marketing experience in the US has shown an adverse experience profile similar to that given above. Additional reports have included rare occurrences of allergic reaction, cogwheel rigidity, dystonic reaction, ecchymosis, emotional lability and tunnel vision. Because of the uncontrolled nature of these spontaneous reports, a causal relationship to buspirone treatment has not been determined.

Physical/Psychological Dependence:
In human and animal studies, buspirone has shown no potential for abuse or diversion and there is no evidence that it causes tolerance, or either physical or psychological dependence.

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Overdose

Signs and Symptoms

In clinical pharmacology trials, doses as high as 375 mg/day were administered to healthy male volunteers. As this dose was approached, the following symptoms were observed: nausea, vomiting, dizziness, drowsiness, miosis, and gastric distress. No deaths have been reported in humans either with deliberate or accidental overdosage of buspirone. Toxicology studies of buspirone yielded the following LD50 values: mice, 655 mg/kg; rats, 196 mg/kg; dogs, 586 mg/kg; and monkeys, 356 mg/kg. These dosages are 160 to 550 times the recommended human daily dose.

Treatment

General symptomatic and supportive measures should be used along with immediate gastric lavage. Respiration, pulse, and blood pressure should be monitored as in all cases of drug overdosage. No specific antidote is known to buspirone, and dialyzability of buspirone has not been determined.

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Dosage

Optimum results are usually seen after three to four weeks of treatment.

HOW TO USE THIS MEDICINE:
Follow the directions for using this medicine provided by your doctor.

This medicine may be taken on an empty stomach or with food.
Store this medicine at room temperature, away from heat and light.
If you miss a dose of this medicine, take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Dosage should be individually adjusted, according to tolerance and response.

The recommended initial dose is 15 mg daily (5 mg 3 times a day). To achieve an optimal therapeutic response, at intervals of 2 to 3 days the dosage may be increased 5 mg per day, as needed. The maximum daily dosage should not exceed 60 mg per day. In clinical trials allowing dose titration, divided doses of 20 to 30 mg per day were commonly employed.

IF USING THIS MEDICINE FOR AN EXTENDED PERIOD OF TIME, obtain refills before your supply runs out.

Patient Information: Do not take any other sedating drugs or drink alcohol while taking this medication. Do not take this medication with a monoamine oxidase inhibitor. Notify physician if you develop muscle spasms, uncontrolled twitching in the face and body, or uncontrolled tongue or jaw movements.

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How Supplied

BuSpar Tablets, 5 mg and 10 mg, are available in bottles of 100 and 500, and in cartons containing 100 individually packaged tablets.

BuSpar Patient Information

Last updated 3/2003

The information in this monograph is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects. This information is generalized and is not intended as specific medical advice. If you have questions about the medicines you are taking or would like more information, check with your doctor, pharmacist, or nurse. Last updated 3/03.

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Buspirone

Brand Name: BuSpar