Clinical toxocity of theophylline in relation to cigarette smoking. A report from the Boston Collaborative Drug Surveillance Program.

Adverse reactions to derivatives of theophylline were studied among 2,766 medical inpatients. The primary diagnosis at discharge was cardiac disease in 23 percent, chronic obstructive pulmonary disease in 22 percent, asthma in 13 percent, pulmonary infection in 10 percent, and other disorders in 3 percent of the patients. Eight hundred seven of the patients were current cigarette smokers, and 1,209 denied smoking. Adverse effects of administration of theophylline were reported in 298 patients (10.8 percent). Gastrointestinal disturbances, reported in 7.8 percent of the recipients, were the most common adverse effects. Others were cardiovascular disturbances (1.2 percent), effects on the central nervous system (0.9 percent), and miscellaneous adverse reactions (0.9 percent). A higher frequency of adverse reactions was associated with higher doses of theophylline; however, cigarette smoking was negatively correlated with the frequency of adverse reactions. Adverse effects were experienced by 13 percent of the nonsmokers, by 11 percent of those who smoked up to 20 cigarettes daily, and by 7 percent of those who smoked more heavily. This association was most apparent among young patients with normal renal function and was least evident among the elderly.