Comparative Pharmacology
Head-to-head clinical analysis: ZANTAC 300 versus ZANTAC 75.
Peer-Reviewed Evidence
Head-to-head clinical analysis: ZANTAC 300 versus ZANTAC 75.
ZANTAC 300 vs ZANTAC 75
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Competitive antagonist of histamine at H2 receptors on gastric parietal cells, reducing basal and stimulated gastric acid secretion.
Competitive inhibitor of histamine at H2 receptors on gastric parietal cells, reducing basal and stimulated gastric acid secretion.
300 mg orally once daily at bedtime or 150 mg orally twice daily.
75 mg orally once daily or 150 mg orally once daily for heartburn; up to 300 mg/day for duodenal ulcer or GERD.
None Documented
None Documented
Approximately 2.5–3 hours in patients with normal renal function; prolonged in renal impairment (creatinine clearance <30 mL/min: up to 6–12 hours).
Terminal elimination half-life is 2.5-3 hours. In elderly patients or those with renal impairment (CrCl <50 mL/min), half-life may extend to 4-6 hours, requiring dose adjustment.
Renal (approximately 30% unchanged active drug via tubular secretion and glomerular filtration); hepatic metabolism to N-oxide, S-oxide, and desmethyl metabolites (about 70% of dose); fecal excretion (minor, <5%).
Renal (60-70% as unchanged drug), hepatic metabolism (30-40% as N-oxide, S-oxide, and desmethyl metabolites), with fecal excretion accounting for <10%.
Category C
Category C
H2 Antagonist
H2 Antagonist