[(Science: drug) inhibits cAMP phosphodiesterase and is often used in conjunction with exogenous dibutyryl cyclic AMP to raise cellular cAMP levels. Other, less potent, methylxanthines are caffeine, theobromine and aminophylline.
[1. An alkaloid found with caffeine in tea leaves (commercial theophylline is prepared synthetically); shares chemical and pharmacologic properties with caffeine and theobromine.