PFIZER's EXIREL (PIRBUTEROL) BRONCHODILATOR IS APPROVABLE

PFIZER's EXIREL (PIRBUTEROL) BRONCHODILATOR IS APPROVABLE, according to FDA's compilation of drug approval activity for October. The firm received notification from the agency on Oct. 17 that the drug, a beta-2 stimulator, had reached the approvable stage. The dosage is EQ 0.2 mg base formulated as an aerosol for inhalation. Approvable status indicates that FDA has completed its review of safety and efficacy data, and that approval for marketing will be granted once the firm and the agency work out final printed labeling. Pfizer has had NDAs pending for Exirel since 1983 for both the aerosol and and and an oral form of the drug for the treatment of chronic obstructive pulmonary disease. Currently, Pfizer markets Exirel in Japan, France, and the UK. In the U.S., Pfizer currently markets two bronchodilator products: Sustaire (theophylline, sustained release) marketed by the Pfipharmecs unit, and the combo product Marax (ephedrine sulfate, theophylline, and hydroxyzine) handled by Roerig. Roerig will market Exirel. According to a new report by SRI on bronchodilator products, the key to physician acceptance in the U.S. of a new beta-2 stimulator is the selectivity of the drug for safety reasons, and its duration of action. SRI indicates that theopylline is still the first line treatment for obstructive pulmonary disease in the U.S., although the effectiveness of beta-2 agonist product is widely accepted. Physician concern, however, over the safety of beta-2 stimulators, particularly inhaled aerosols which can be misused by patients, is slowing growth for the beta-2 stimulator product class. The concern of physicians over the safety of beta-2 products in metered dose inhalors was demonstrated by the objections of physician specialists to FDA's proposal three years ago to allow the OTC marketing of metaproterenol (Boehringer Ingelheim's Alupent and Dorsey's Metaprel). Other marketed beta-2 agonists include albuterol (Glaxo's Ventolin and Schering's Proventil) and Sterling's Tornalate (bitolterol). A beta-2 agonist with a good safety profile and a duration of action long enough to last through the night, however, would be a strong entry in the U.S. bronchodilator market. Exirel is the first of a group of pending Pfizer NDA's to move to the approvable stage since William Steere became head of the firm's U.S. pharmaceutical business last February. Still under review by the agency are NDA's for the antihypertensive Cardovar (trimazosin) and for Trosyd (tioconazole) for use as a vaginal antifungal.