Some Recent Advances in the Management of Asthma

Abstract

serum theophylline levels has resulted in a better understanding of the pharmacokinetics of the methylxanthines, resulting in more physiologic use of these drugs. With oral aminophylline, optimum serum levels occur with the administration of 6 mg/kg every six hours or about 300 to 400 mg four times daily in the average adult.1 Liver disease and congestive heart failure decrease the rate of metabolism of theophylline and, therefore, result in higher blood levels.2 A recent therapeutic advance in oral theophylline has been the sustained-release oral preparations. A dozen or so acceptable sustained-release theophyllines are commercially available, and these seem to give more stable blood levels with less peak-and-trough effect. Furthermore, the drugs can be administered twice daily, and this should increase patient compliance. During acute attacks of asthma, an initial intravenous (IV) loading dose of aminophylline (6 mg/kg) is given during 20 minutes to patients who were not taking an oral theophylline. For those on an oral maintenance theophyl¬ line regimen, this loading dose is eliminated. Recommend¬ ed IV maintenance doses are given in Table 1. The initial maintenance dose is 0.5 mg/kg/hr by constant IV infusion in healthy nonsmoking adults. In older patients and in those with cardiac or hepatic disease, a lower initial maintenance dose is recommended because of longer serum half-life.3