Absorption: Well absorbed from PO dosage forms; absorption from extended-release dosage forms is slow but complete.
Distribution: Widely distributed; crosses the placenta and into breast milk; does not distribute into adipose tissue.
Metabolism/Excretion: 90% metabolized by the liver to several metabolites (including the active metabolites, caffeine, and 3–methylxanthine); metabolites are renally excreted; 10% excreted unchanged by the kidneys.
Half-life: Theophylline — Premature infants: 20–30 hr; Term infants: 11–25 hr; Children 1–4 yr: 3.4 hr; Children 6–17 yr: 3.7 hr; Adults: 9–10 hr (↑ in patients >60 yr, patients with HF or liver disease; ↓ in cigarette smokers).
CNS: SEIZURES, anxiety, headache, insomnia, irritability.
CV: ARRHYTHMIAS, tachycardia, angina, palpitations.
GI: nausea, vomiting, anorexia.
Neuro: tremor.
Dose should be determined by theophylline serum level monitoring. Loading dose should be
↓ or eliminated if theophylline preparation has been used in preceding 24 hr. Aminophylline is 80% theophylline (100 mg aminophylline = 80 mg theophylline). Extended-release (controlled-release, sustained-release) products may be given q 8–24 hr, depending upon the formulation.
- PO (Adults Healthy, Non-smoking): Loading dose — 5 mg/kg, followed by 10 mg/kg/day divided q 8–12 hr (not to exceed 900 mg/day).
- PO (Adults with HF, Cor Pulmonale, or Liver Dysfunction): Loading dose — 5 mg/kg, followed by 5 mg/kg/day divided q 8–12 hr (not to exceed 400 mg/day).
- PO (Children 12–16 yr, Non-smoking): Loading dose — 5 mg/kg, followed by 13 mg/kg/day divided q 8–12 hr.
- PO (Children 9–12 yr, adolescent and adult smokers <50 yr): Loading dose — 5 mg/kg, followed by 16 mg/kg/day divided q 8–12 hr.
- PO (Children 1–9 yr): Loading dose — 5 mg/kg, followed by 20–24 mg/kg/day divided q 8–12 hr.
- PO (Infants 6 mo–1 yr): Loading dose — 5 mg/kg, followed by 12–18 mg/kg/day divided q 6–8 hr.
- PO (Infants 6 wk–6 mo): Loading dose — 5 mg/kg, followed by 10 mg/kg/day divided q 6–8 hr.
- PO (Neonates up to 6 wks): Loading dose — 4 mg/kg, followed by 4 mg/kg/day divided q 12 hr.
- IV (Adults and Children): See aminophylline monograph for IV doses.
Elixophyllin, Theo-24, Theochron
Pulmophylline, Theolair, Uniphyl
Therapeutic Classification: bronchodilators
Pharmacologic Classification: xanthines
(bronchodilation)
†Provided that a loading dose has been given and steady-state blood levels exist.
