Comparative Pharmacology
Head-to-head clinical analysis: MAXAIR versus SOMOPHYLLIN.
Peer-Reviewed Evidence
Head-to-head clinical analysis: MAXAIR versus SOMOPHYLLIN.
MAXAIR vs SOMOPHYLLIN
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Beta-2 adrenergic receptor agonist; relaxes bronchial smooth muscle via increased intracellular cAMP.
Theophylline is a methylxanthine that relaxes bronchial smooth muscle by inhibiting phosphodiesterase, increasing cAMP levels, and antagonizing adenosine receptors. It also has anti-inflammatory and immunomodulatory effects.
2 inhalations (340 mcg) via oral inhalation every 4-6 hours as needed for bronchospasm; not to exceed 12 inhalations per day.
Oral: 200–400 mg every 6 hours; IV: 6 mg/kg loading dose over 30 minutes, then 0.4–0.6 mg/kg/h continuous infusion.
None Documented
None Documented
3.5–4.0 hours; clinically, this supports dosing every 4–6 hours as needed.
The terminal elimination half-life of theophylline is approximately 8 hours in healthy non-smoking adults (range 3-12 hours). It is prolonged in patients with hepatic cirrhosis (up to 30 hours), heart failure (up to 30 hours), and in neonates (20-30 hours). Smoking (including marijuana) decreases half-life to 4-5 hours. Half-life is shorter in children (3-5 hours). Clinical context: Due to narrow therapeutic index, half-life variability necessitates therapeutic drug monitoring.
Renal excretion of unchanged drug accounts for approximately 90% of elimination; fecal excretion is minimal (<5%).
Theophylline is primarily eliminated by hepatic metabolism (>90%), with only about 10-15% excreted unchanged in urine. Renal excretion of the parent drug is minor; however, metabolites are excreted renally. Biliary/fecal excretion accounts for less than 1%.
Category C
Category C
Bronchodilator
Bronchodilator