Theophylline is used in the treatment of bronchospasm - ie in reversible airways obstruction and severe asthma. It is a bronchodilator available in modified release preparations which are able to provide therapeutic plasma concentrations for 12 hours.
There is a narrow margin between the therapeutic and toxic doses, and the half life can be modified by a variety of factors, making a therapeutic dose hard to achieve.
Factor which increase the half life include heart failure, cirrhosis, viral infection and drugs like cimetidine, ciprofloxacin, erythromycin and the oral contraceptive pill.
The half life is decreased by smoking, heavy drinking and drugs like phenytoin, carbamazepine, rifampicin and barbiturates.
Note that, unlike many other drugs, the proprietry brand of theophylline strongly influences the pharmacodynamics. Thus theophylline should be prescribed by brand name as well as generic name.
Last reviewed 01/2018