Comparative Pharmacology
Head-to-head clinical analysis: DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE versus NORPACE.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE versus NORPACE.
DEXTROMETHORPHAN HYDROBROMIDE AND QUINIDINE SULFATE vs NORPACE
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Dextromethorphan is an uncompetitive NMDA receptor antagonist and sigma-1 receptor agonist; quinidine is a CYP2D6 inhibitor that increases dextromethorphan bioavailability.
Class Ic antiarrhythmic agent; blocks voltage-gated sodium channels, slowing conduction velocity and prolonging refractory periods in cardiac tissue.
One capsule (dextromethorphan 20 mg/quinidine 10 mg) orally once daily, with a maximum dose of two capsules per day.
150 mg orally every 6 hours (maximum 300 mg per dose), extended-release formulation 300 mg every 12 hours.
None Documented
None Documented
Dextromethorphan: 2-4 hours (extensive metabolizers); quinidine: 6-8 hours (inhibits CYP2D6, prolonging dextromethorphan half-life in poor metabolizers to >20 hours)
Terminal elimination half-life: 6-8 hours (normal renal function); prolonged in renal impairment (up to 24 hours).
Renal: quinidine 15-25% unchanged, dextromethorphan <1% unchanged; biliary/fecal: quinidine metabolites ~5%, dextromethorphan metabolites ~60-80% as dextrorphan conjugates
Renal: 40-60% unchanged; biliary/fecal: minor (10-20%).
Category A/B
Category C
Antiarrhythmic (Class Ia)
Antiarrhythmic (Class Ia)