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.

Acefylline (Theophylline-7-acetic acid), a stimulant drug of the xanthine chemical class, acts as an adenosine receptor antagonist. It is combined with diphenhydramine in the pharmaceutical preparation Etanautine to help offset its stimulant effects

Diphylline (Diprophylline) is a xanthine derivative. Diphylline exerts bronchodilator effects and to a lesser extent vasodilator and diuretic properties. Diphylline probably acts as a competitive inhibitor of phosphodiesterase which leads to an increase in intracellular cAMP. This results in relaxation of bronchial smooth muscle and other smooth muscles. Diphylline may also antagonize adenosinereceptors. Diphylline is used in the treatment of acute bronchial asthma, chronic bronchitis and emphysema.

Bithionol (Actamer), formerly marketed as an active ingredient in various topical drug products, was shown to be a potent photosensitizer with the potential to cause serious skin disorders. Approvals of the NDA's for bithionol drug products were withdrawn on October 24, 1967.

Aminophylline (Phyllocontin) is a competitive nonselective phosphodiesterase inhibitor giving a bronchodilatory effect.

Istradefylline (KW-6002)(Ki of 2.2 nM) is a selective adenosine A2A receptor (A2AR) antagonist, which is under development in Phase 3 trails. It has been used in trials studying the treatment and basic science of Drug Abuse, Sleep Disorder, Hepatic Impairment, Parkinson's Disease, and Restless Legs Syndrome, among others.