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MAXAIR (pirbuterol) AUTOHALER, like other inhaled beta adrenergic agonists, can produce a clinically significant cardiovascular effect in some patients, as measured by pulse rate, blood pressure and/or symptoms. Although such effects are uncommon after administration of MAXAIR (pirbuterol) AUTOHALER at recommended doses, if they occur, the drug may need to be discontinued. In addition, beta-agonists have been reported to produce ECG changes, such as flattening of the Twave, prolongation of the QTc interval, and ST segment depression. The clinical significance of these findings is unknown. Therefore, MAXAIR (pirbuterol) AUTOHALER, like all sympathomimetic amines, should be used with caution in patients with cardiovascular disorders, especially coronary insufficiency, cardiac arrhythmias, and hypertension.
MAXAIR (pirbuterol) AUTOHALER can produce paradoxical bronchospasm, which can be life threatening. If paradoxical bronchospasm occurs, MAXAIR (pirbuterol) AUTOHALER should be discontinued immediately and alternative therapy instituted. It should be recognized that paradoxical bronchospasm, when associated with inhaled formulations, frequently occurs with the first use of a new canister or vial.
Use of Anti-Inflammatory Agents
The use of beta adrenergic agonist bronchodilators alone may not be adequate to control asthma in many patients. Early consideration should be given to adding anti-inflammatory agents, e.g., corticosteroids.
Deterioration of Asthma
Asthma may deteriorate acutely over a period of hours or chronically over several days or longer. If the patient needs more doses of MAXAIR (pirbuterol) AUTOHALER than usual, this may be a marker of destabilization of asthma and requires reevaluation of the patient and the treatment regimen, giving special consideration to the possible need for anti-inflammatory treatment, e.g., corticosteroids.
Since pirbuterol is a sympathomimetic amine, it should be used with caution in patients with cardiovascular disorders, including ischemic heart disease, hypertension, or cardiac arrhythmias, in patients with hyperthyroidism or diabetes mellitus, and in patients who are unusually responsive to sympathomimetic amines or who have convulsive disorders. Significant changes in systolic and diastolic blood pressure could be expected to occur in some patients after use of any beta adrenergic aerosol bronchodilator.
Beta adrenergic agonist medications may produce significant hypokalemia in some patients, possibly through intracellular shunting, which has the potential to produce adverse cardiovascular effects. The decrease is usually transient, not requiring supplementation.
Carcinogenesis, Mutagenesis and Impairment of Fertility
In a 2-year study in Sprague-Dawley rats, pirbuterol hydrochloride administered at dietary doses of 1.0, 3.0, and 10 mg/kg (approximately 3, 10, and 35 times the maximum recommended daily inhalation dose for adults and children on a mg/m2 basis) showed no evidence of carcinogenicity. In an18-month study in mice at dietary doses of1.0, 3.0, and 10mg/kg (approximately 2, 5, and 15times the maximum recommended daily inhalation dose for adults and children on a mg/m2 basis) no evidence of tumorigenicity was seen. Reproduction studies in rats administered pirbuterol hydrochloride at oral doses of 1, 3, and 10mg/kg (approximately 3,10, and 35 times the maximum recommended daily inhalation dose for adults on a mg/m2 basis) revealed no evidence of impaired fertility.
Pirbuterol dihydrochloride showed no evidence of mutagenicity in in vitro assays and host-mediated microbial (Ames) assays for point mutations and in vivo tests for somatic or germ cell effects following acute and subchronic treatment in mice (cytogenicity assays).
Teratogenic Effects – Pregnancy Category C
Pirbuterol was not teratogenic in rats administered oral doses of 30, 100, and 300 mg/kg (approximately 100, 340, and 1000 times the maximum recommended daily inhalation dose for adults on a mg/m2 basis). Pirbuterol was not teratogenic in rabbits administered oral doses of 30 and 100 mg/kg (approximately 200 and 680 times the maximum recommended inhalation dose for adults on a mg/m2 basis). However, pirbuterol at anoral dose of 300mg/kg (approximately 2000times the maximum recommended daily inhalation dose in adults on a mg/m2 basis) caused abortions and fetal death.
There are no adequate and well-controlled studies in pregnant women. Pirbuterol should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Labor and Delivery
Because of the potential for beta-agonist interference with uterine contractility, use of MAXAIR (pirbuterol) AUTOHALER for relief of bronchospasm during labor should be restricted to those patients in whom the benefits clearly outweigh the risk.
It is not known whether pirbuterol is excreted in human milk. Therefore, MAXAIR (pirbuterol) AUTOHALER should be used during nursing only if the potential benefit justifies the possible risk to the newborn.
MAXAIR (pirbuterol) AUTOHALER is not recommended for patients under the age of 12 years because of insufficient clinical data to establish safety and effectiveness.
Last reviewed on RxList: 11/24/2008
This monograph has been modified to include the generic and brand name in many instances.
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