Aerosol pentamidine-induced bronchoconstriction. Predictive factors and preventive therapy.

Objective: To describe the frequency of aerosol pentamidine-induced bronchoconstriction, its relationship to non-specific airway responsiveness, and its response to preventive therapy using salbutamol, ipratropium bromide, or sodium cromoglycate.

Methods: Consecutive HIV-infected individuals starting prophylactic AP were eligible if they had not been previously treated with this agent. Simple spirometry was performed before and 10 min after a single 60-mg dose given through an ultrasonic nebulizer. Methacholine challenge was performed in all subjects 24 h to four days after the initial AP dose. Subjects with a change in FEV1 (delta FEV1) greater than or equal to 10 percent decrease after the initial AP dose were restudied on three separate occasions (greater than 24 hours apart) after premedication with two puffs of salbutamol (200 micrograms), ipratropium bromide (40 micrograms), or sodium cromoglycate (2 mg), in random order.

Results: Fifty-three subjects were studied. The median delta FEV1 after a single dose of AP was -7.0 percent (range: -47 percent, 1.8 percent). The delta FEV1 following AP was only partially predicted by the degree of nonspecific bronchial responsiveness as measured by a standard methacholine challenge. Age, current smoking, history of asthma, baseline FEV1, or a prior episode of PCP failed to predict the delta FEV1 following AP. Eighteen subjects (34 percent) had a delta FEV1 greater than or equal to 10 percent decrease (median: -17.0 percent). In these subjects, after premedication with salbutamol, ipratropium bromide, and sodium cromoglycate, the median delta FEV1 was 1.0, 0.8, and -9.6 percent, respectively.

Conclusion: Aerosol pentamidine produced a decrease in FEV1 greater than or equal to 10 percent in 34 percent of subjects. This was not accurately predicted by the methacholine response. The bronchoconstriction induced by AP was effectively prevented by either salbutamol or ipratropium, whereas cromoglycate was only partially effective.