Anticholinergic and sympathomimetic combination therapy of asthma
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The role of the anticholinergic drug, ipratropium bromide, in maintenance antiasthmatic therapy was evaluated in a double-blind crossover trial of three bronchodilator regimens: (1) inhaled ipratropium, placebo, and oral oxtriphylline; (2) inhaled fenoterol, placebo, and oral oxtriphylline; and (3) both inhaled ipratropium and fenoterol plus oral oxtriphylline. Twenty-two asthmatics were treated with all three regimens, each for 1 mo, allocated in random sequence. On the first and last treatment days of each month, spirometric measurements were performed before and 0.5, 1, 2, 3, 4, and 6 hr after administration of the test drugs. On the first treatment day of each month, all regimens produced significant bronchodilatation at 30 min after dose, an improvement that declined between 3 and 6 hr after dose. After continuous administration for 1 mo the two combinations employing fenoterol showed a decline in bronchodilator responsiveness from the initial treatment day, measured as the level of response (V50) or duration of response (FEV1, VC). Ipratropium plus oxtriphylline showed no such decline, suggesting the development of tolerance to long-term administration of fenoterol. Overall benefit at the end of 1 mo, measured as the area under the curves of FEV1, VC, or V50 vs time after dose, was greatest for the triple drug regimen. There were no differences in heart rate, blood pressure response, or side effects among the three treatments. It is concluded that when the anticholinergic drug ipratropium is administered concurrently with an inhaled beta 2 agonist and an oral theophylline derivative, increased bronchodilatation occurs with no detectable additional side effects.
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