Buspirone Hydrochloride 15 mg Tablet, 500-count

WARNINGS The administration of buspirone hydrochloride 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 hydrochloride has been added to a regimen including an MAOI. Therefore, it is recommended that buspirone hydrochloride not be used concomitantly with an MAOI.

Serotonin Syndrome The development of a potentially life-threatening serotonin syndrome has been reported with SNRIs, SSRIs, and other serotonergic drugs, including buspirone, alone but particularly with concomitant use of other serotonergic drugs (including triptans), with drugs that impair metabolism of serotonin (in particular, MAOIs, including reversible MAOIs such as linezolid and intravenous methylene blue), or with antipsychotics or other dopamine antagonists. Serotonin syndrome symptoms may include mental status changes (e.g., agitation, hallucinations, delirium, and coma), autonomic instability (e.g., tachycardia, labile blood pressure, dizziness, diaphoresis, flushing, hyperthermia), neuromuscular changes (e.g., tremor, rigidity, myoclonus, hyperreflexia, incoordination), seizures, and/or gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea).

Patients should be monitored for emergence of serotonin syndrome. The concomitant use of buspirone with MAOIs intended to treat depression is contraindicated. Buspirone should also not be started in a patient who is being treated with reversible MAOIs such as linezolid or intravenous methylene blue.

All reports with methylene blue that provided information on the route of administration involved intravenous administration in the dose range of 1 mg/kg to 8 mg/kg. There have been no reports involving the administration of methylene blue by other routes (such as oral tablets or local tissue injection) or at lower doses. There may be circumstances when it is necessary to initiate treatment with a reversible MAOI such as linezolid or intravenous methylene blue in a patient taking buspirone.

Buspirone should be discontinued before initiating treatment with the reversible MAOI (see CONTRAINDICATIONS , DOSAGE AND ADMINISTRATION and DRUG INTERACTIONS ). If concomitant use of buspirone with a 5-hydroxytryptamine receptor agonist (triptan) is clinically warranted, careful observation of the patient is advised, particularly during treatment initiation and dose increases. The concomitant use of buspirone with serotonin precursors (such as tryptophan) is not recommended.

Treatment with buspirone and any concomitant serotonergic or antidopaminergic agents, including antipsychotics, should be discontinued immediately if the above events occur and supportive symptomatic treatment should be initiated. Because buspirone hydrochloride has no established antipsychotic activity, it should not be employed in lieu of appropriate antipsychotic treatment.

ADVERSE REACTIONS (See also PRECAUTIONS ) Commonly Observed The more commonly observed untoward events associated with the use of buspirone hydrochloride not seen at an equivalent incidence among placebo-treated patients include dizziness, nausea, headache, nervousness, lightheadedness, and excitement. Associated with Discontinuation of Treatment One guide to the relative clinical importance of adverse events associated with buspirone hydrochloride is provided by the frequency with which they caused drug discontinuation during clinical testing.

Approximately 10% of the 2200 anxious patients who participated in the buspirone hydrochloride premarketing clinical efficacy trials in anxiety disorders lasting 3 to 4 weeks discontinued treatment due to an adverse event. The more common events causing discontinuation included: central nervous system disturbances (3.4%), primarily dizziness, insomnia, nervousness, drowsiness, and lightheaded feeling; gastrointestinal disturbances (1.2%), primarily nausea; and miscellaneous disturbances (1.1%), primarily headache and fatigue.

In addition, 3.4% of patients had multiple complaints, none of which could be characterized as primary. Incidence in Controlled Clinical Trials The table that follows enumerates adverse events that occurred at a frequency of 1% or more among buspirone hydrochloride patients who participated in 4-week, controlled trials comparing buspirone hydrochloride with placebo. The frequencies were obtained from pooled data for 17 trials.

The prescriber should be aware that these figures cannot be used to predict the incidence of side effects in the course of usual medical practice where patient characteristics and other factors differ from those which prevailed in the clinical trials. Similarly, the cited frequencies cannot be compared with figures obtained from other clinical investigations involving different treatments, uses, and investigators. Comparison of the cited figures, however, does provide the prescribing physician with some basis for estimating the relative contribution of drug and nondrug factors to the side-effect incidence rate in the population studied.

TREATMENT-EMERGENT ADVERSE EXPERIENCE INCIDENCE IN PLACEBO-CONTROLLED CLINICAL TRIALS Events reported by at least 1% of buspirone patients are included. (Percent of Patients Reporting) Buspirone Placebo Adverse Experience (n = 477) (n = 464) Cardiovascular Tachycardia/Palpitations 1 1 CNS Dizziness 12 3 Drowsiness 10 9 Nervousness 5 1 Insomnia 3 3 Lightheadedness 3 - Decreased concentration 2 2 Excitement 2 - Anger/Hostility 2 - Confusion 2 - Depression 2 2 EENT Blurred vision 2 - Gastrointestinal Nausea 8 5 Dry mouth 3 4 Abdominal/gastric distress 2 2 Diarrhea 2 - Constipation 1 2 Vomiting 1 2 Musculoskeletal Musculoskeletal aches/pains 1 - Neurological Numbness 2 - Paresthesia 1 - Incoordination 1 - Tremor 1 - Skin Skin rash 1 - Miscellaneous Headache 6 3 Fatigue 4 4 Weakness 2 - Sweating/Clamminess 1 - - Incidence less than 1%.

Other Events Observed During the Entire Premarketing Evaluation of Buspirone Hydrochloride During its premarketing assessment, buspirone hydrochloride were evaluated in over 3500 subjects. This section reports event frequencies for adverse events occurring in approximately 3000 subjects from this group who took multiple doses of buspirone hydrochloride in the dose range for which buspirone is being recommended (i.e., the modal daily dose of buspirone hydrochloride fell between 10 mg and 30 mg for 70% of the patients studied) and for whom safety data were systematically collected.

The conditions and duration of exposure to buspirone hydrochloride varied greatly, involving well-controlled studies as well as experience in open and uncontrolled clinical settings. As part of the total experience gained in clinical studies, various adverse events were reported. In the absence of appropriate controls in some of the studies, a causal relationship to buspirone hydrochloride treatment cannot b…

Drug Interactions Psychotropic Agents MAO inhibitors The use of monoamine oxidase inhibitors (MAOIs) intended to treat depression with buspirone or within 14 days of stopping treatment with buspirone is contraindicated because of an increased risk of serotonin syndrome and/or elevated blood pressure. The use of buspirone within 14 days of stopping an MAOI intended to treat depression is also contraindicated. Starting buspirone in a patient who is being treated with reversible MAOIs such as linezolid or intravenous methylene blue is also contraindicated because of an increased risk of serotonin syndrome (see WARNINGS , DOSAGE AND ADMINISTRATION AND CONCOMITANT DRUG ).

Amitriptyline After addition of buspirone to the amitriptyline dose regimen, no statistically significant differences in the steady-state pharmacokinetic parameters (C max , AUC, and C min ) of amitriptyline or its metabolite nortriptyline were observed. Diazepam After addition of buspirone to the diazepam dose regimen, no statistically significant differences in the steady-state pharmacokinetic parameters (C max , AUC, and C min ) were observed for diazepam, but increases of about 15% were seen for nordiazepam, and minor adverse clinical effects (dizziness, headache, and nausea) were observed.

Haloperidol 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. Nefazodone (See Inhibitors and Inducers of Cytochrome P450 3A4 (CYP3A4) ) Trazodone There is one report suggesting that the concomitant use of trazodone hydrochloride and buspirone may have caused 3 to 6-fold elevations on SGPT (ALT) in a few patients.

In a similar study attempting to replicate this finding, no interactive effect on hepatic transaminases was identified. Triazolam/Flurazepam Coadministration of buspirone with either triazolam or flurazepam did not appear to prolong or intensify the sedative effects of either benzodiazepine. Other Psychotropics 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.

Inhibitors and Inducers of Cytochrome P450 3A4 (CYP3A4) Buspirone has been shown in vitro to be metabolized by CYP3A4. This finding is consistent with the in vivo interactions observed between buspirone and the following: Diltiazem and Verapamil In a study of nine healthy volunteers, coadministration of buspirone (10 mg as a single dose) with verapamil (80 mg t.i.d.) or diltiazem (60 mg t.i.d.) increased plasma buspirone concentrations (verapamil increased AUC and C max of buspirone 3.4-fold while diltiazem increased AUC and C max 5.5-fold and 4-fold, respectively).

Adverse events attributable to buspirone may be more likely during concomitant administration with either diltiazem or verapamil. Subsequent dose adjustment may be necessary and should be based on clinical assessment. Erythromycin In a study in healthy volunteers, coadministration of buspirone (10 mg as a single dose) with erythromycin (1.5 g/day for 4 days) increased plasma buspirone concentrations (5-fold increase in C max and 6-fold increase in AUC).

These pharmacokinetic interactions were accompanied by an increased incidence of side effects attributable to buspirone. If the two drugs are to be used in combination, a low dose of buspirone (e.g., 2.5 mg b.i.d.) is recommended. Subsequent dose adjustment of either drug should be based on clinical assessment.

Grapefruit Juice In a study in healthy volunteers, coadministration of buspirone (10 mg as a single dose) with grapefruit juice (200 mL double-strength t.i.d. for 2 days) increased plasma buspirone concentrations (4.3-fold increase in C max ; 9.2-fold increase in AUC). Patients receiving buspirone should be advised to avoid drinking such large amounts of grapefruit juice. Itracon…