Theobromine (3,7-Dimethylxanthine), a xanthine alkaloid, is used as a bronchodilator and as a vasodilator.

Doxofylline (Doxophylline) is a methylxanthine derivative with the presence of a dioxolane group in position 7. As a drug used in the treatment of asthma, doxofylline has shown similar efficacy to theophylline but with significantly fewer side effects in animal and human studies.

Theophylline (1,3-Dimethylxanthine) is a methyl xanthine derivative from tea with diuretic, smooth muscle relaxant, bronchial dilation, cardiac, and central nervous system stimulant activities. It inhibits the 3', 5'-cyclic nucleotide phosphodiesterase that degrades cyclic AMP, thus potentiating the actions of agents that act through adenylyl cyclases and cyclic AMP.

Inosine (NSC-20262) is a purine nucleoside that has hypoxanthine linked by the N9 nitrogen to the C1 carbon of ribose. It has immunomodulatory, neuroprotective, and analgesic properties.

Theophylline monohydrate (Quibron) appears to inhibit phosphodiesterase and prostaglandin production, regulate calcium flux and intracellular calcium distribution, and antagonize adenosine. Theophylline monohydrate is a natural alkaloid derivative of xanthine isolated from the plants Camellia sinensis and Coffea arabica. Physiologically, this agent relaxes the bronchial smooth muscle, produces vasodilation (except in cerebral vessels), stimulates the CNS, stimulates the cardiac muscle, induces diuresis, and increases gastric acid secretion; it may also suppress inflammation and improve contractility of the diaphragm.