A natural alkaloid derivative of xanthine isolated from the plants Camellia sinensis and Coffea arabica.
Theophylline appears to inhibit phosphodiesterase and prostaglandin production, regulate calcium flux and intracellular calcium distribution, and antagonize adenosine.
Physiologically, this agent relaxes bronchial smooth muscle, produces vasodilation (except in cerebral vessels), stimulates the central nervous system, stimulates cardiac muscle, induces diuresis, and increases gastric acid secretion; it may also suppress inflammation and improve contractility of the diaphragm.
Adult
PO
Acute bronchospasm: patients not taking theophylline or other xanthine medication. Loading dose: 5 mg/kg.
Chronic bronchospasm 300-1,000 mg in divided doses 6-8 hrly. Modified-release preparation: 175-500 mg 12 hrly.
IV
Acute severe bronchospasm - patients not taking theophylline or other xanthine medication: Loading dose: 4-5 mg/kg by infusion over 20-30 min. Maintenance dose: 0.4-0.6 mg/kg/hr.
