Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
DEXTROMETHORPHAN POLISTIREX vs CODEPREX
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Dextromethorphan polistirex is an NMDA receptor antagonist and sigma-1 receptor agonist. It inhibits serotonin reuptake and acts on the brain stem cough center to elevate the threshold for coughing.
Codeine is a prodrug converted to morphine via CYP2D6; morphine acts as a mu-opioid receptor agonist, while homatropine is an anticholinergic that reduces respiratory secretions.
Symptomatic relief of nonproductive cough associated with upper respiratory tract infections,Off-label: Management of pseudobulbar affect (with quinidine),Off-label: Treatment of neuropathic pain
Cough suppression (FDA-approved)
30-60 mg orally every 12 hours; not to exceed 120 mg in 24 hours.
Adults: 1 tablet (containing 5 mg hydrocodone and 325 mg acetaminophen) orally every 4-6 hours as needed for pain; maximum 6 tablets per day.
Terminal half-life: 13–19 hours; clinical context: extended-release formulation due to polistirex complex; time to steady-state: ~3 days
4-6 hours (prolonged to 10-12 hours in hepatic impairment)
Hepatic via CYP2D6 (O-demethylation to dextrorphan, active metabolite). Also undergoes N-demethylation via CYP3A4. Polymorphic metabolism (poor metabolizers at risk of toxicity).
Codeine undergoes O-demethylation via CYP2D6 to morphine; also N-demethylation to norcodeine via CYP3A4; homatropine is minimally metabolized.
Renal: ~45% as unchanged drug and metabolites (dextrorphan conjugates); fecal: <2%; biliary: minimal
Renal: 60% as unchanged drug; Hepatic metabolism: 30% (inactive metabolites); Fecal: 10%
~50% bound; primarily to albumin
92% (primarily to albumin)
Vd: ~5–6 L/kg; clinical meaning: extensive tissue distribution, including CNS
1.5-2.0 L/kg (extensive tissue distribution)
Oral (polistirex): approximately 50–60% (first-pass metabolism reduces systemic availability)
Oral: 70-80% (first-pass metabolism reduces from 100% IV)
No specific dosing adjustment provided for dextromethorphan polistirex; use with caution in severe renal impairment (Cr Cl < 30 m L/min) due to potential accumulation of metabolites.
Hydrocodone: GFR 30-80 m L/min: no adjustment; GFR 10-29 m L/min: reduce dose by 50% or extend interval to every 8-12 hours; GFR <10 m L/min: use with caution, consider alternative. Acetaminophen: GFR <10 m L/min: extend dosing interval to every 8 hours.
No specific dosing adjustment provided; use with caution in severe hepatic impairment (Child-Pugh class C) due to reduced clearance.
Child-Pugh Class A: no adjustment; Class B: reduce dose by 50% and extend interval to every 8 hours; Class C: contraindicated due to acetaminophen toxicity risk and impaired hydrocodone metabolism.
Children 6-12 years: 15-30 mg orally every 12 hours; not to exceed 60 mg in 24 hours. Children 2-5 years: 7.5-15 mg orally every 12 hours; not to exceed 30 mg in 24 hours. Not recommended under 2 years.
Not recommended for pediatric use (no safety and efficacy data established).
Elderly patients may be more sensitive to anticholinergic effects; use the lowest effective dose and monitor for adverse effects such as sedation and dizziness.
Start at low end of dosing range (1 tablet every 6 hours) due to increased sensitivity, reduced renal function, and risk of cognitive impairment.
No FDA black box warning.
Risk of respiratory depression, especially in children; contraindicated for postoperative pain management in children after tonsillectomy/adenoidectomy; contraindicated in children <12 years, and in children <18 years with risk factors for respiratory depression.
Do not use with MAOIs or within 14 days of stopping MAOIs,Risk of serotonin syndrome when used with serotonergic drugs,Caution in patients with G6PD deficiency, hepatic impairment, or chronic cough associated with smoking, asthma, or emphysema,QT prolongation risk at supratherapeutic doses,Misuse potential with high doses causing dissociative effects
Respiratory depression; ultra-rapid metabolizers of CYP2D6 at risk of morphine toxicity; use in breastfeeding may cause infant opioid toxicity; anticholinergic effects of homatropine; risk of abuse and dependence; CNS depression with other depressants.
Concurrent use or within 14 days of MAOIs,Hypersensitivity to dextromethorphan or any component,Use in children under 2 years of age (OTC products)
Hypersensitivity to codeine or homatropine; respiratory depression; acute or severe bronchial asthma; GI obstruction; paralytic ileus; children <12 years; children <18 years with tonsillectomy/adenoidectomy; use with MAOIs or within 14 days; breastfeeding women with CYP2D6 ultrarapid metabolism.
Avoid grapefruit and grapefruit juice as they may alter metabolism. Take with or without food; food does not significantly affect absorption.
Grapefruit juice may inhibit CYP2D6 and reduce codeine conversion to morphine, potentially decreasing efficacy. High-fat meals may delay absorption of codeine. Avoid alcohol.
No well-controlled studies in pregnant women. Animal studies have not shown evidence of fetal harm. Based on limited human data, risk of major congenital malformations is low. Avoid use in first trimester due to theoretical risk based on weak NMDA antagonism.
Based on available data, codeine is pregnancy category C. First trimester: Avoid due to possible association with congenital malformations (e.g., cardiovascular defects) from retrospective studies, though risk is low. Second and third trimesters: Risk of neonatal respiratory depression if used near term; chronic use may lead to neonatal withdrawal syndrome. Avoid if possible.
Limited data; excreted in human breast milk in low amounts (M/P ratio not established). Theoretical risk of CNS depression in infant. Use with caution, especially in neonates or preterm infants. Consider immediate-release formulations if necessary.
Codeine is excreted into breast milk. M/P ratio is approximately 2.5. Use with caution due to risk of infant CNS depression, especially in mothers who are CYP2D6 ultra-rapid metabolizers. AAP recommends lowest effective dose for shortest duration; monitor infant for drowsiness, difficulty breathing, or poor feeding.
No specific dose adjustments recommended for pregnancy; however, use lowest effective dose due to altered pharmacokinetics (increased volume of distribution, decreased plasma protein binding) potentially leading to reduced peak concentrations but unchanged half-life.
No standard dose adjustment required, but avoid use in third trimester due to risk of neonatal respiratory depression. If used, use lowest effective dose for shortest duration. Monitor for signs of maternal respiratory depression; consider reduced dose in patients with decreased respiratory reserve.
Dextromethorphan polistirex is an extended-release formulation allowing twice-daily dosing. Its antitussive effect lasts up to 12 hours. Caution in patients with asthma or COPD as it may reduce mucociliary clearance. Avoid concurrent use with MAOIs due to risk of serotonin syndrome. Not effective for chronic cough and should not be used for more than 7 days.
CODEPREX (codeine/guaifenesin) is a combination antitussive/expectorant. Codeine is a prodrug metabolized by CYP2D6 to morphine; ultra-rapid metabolizers risk toxicity. Avoid in children <18 years due to respiratory depression risk. Use with caution in patients with COPD or respiratory insufficiency. Constipation is common; consider prophylactic laxatives.
Do not crush or chew the extended-release capsules or suspension; swallow whole or shake suspension well before use.,Do not exceed recommended doses; may cause drowsiness, avoid driving or operating machinery.,Discontinue use and consult healthcare provider if cough persists more than 7 days or is accompanied by fever, rash, or headache.,Avoid alcohol and other CNS depressants as they may increase sedation.,Inform healthcare provider if you are taking MAOIs (e.g., for depression, Parkinson's) or SSRIs to avoid serotonin syndrome.,Keep out of reach of children; overdose can be fatal.
Do not exceed recommended dose; may cause drowsiness, avoid driving or operating machinery until you know how this medication affects you.,Avoid alcohol and other CNS depressants as they increase sedation and respiratory depression risk.,Do not use in children under 18 years of age due to risk of serious breathing problems.,Contact your doctor if cough persists for more than 7 days or is accompanied by fever, rash, or persistent headache.,May cause constipation; increase fluid and fiber intake, and consider a stool softener if needed.,Store at room temperature away from moisture and heat.
"The combination of dextromethorphan, a centrally acting antitussive with NMDA receptor antagonist and sigma-1 receptor agonist properties, and aceprometazine, a phenothiazine neuroleptic with strong antihistaminergic and moderate anticholinergic and antidopaminergic effects, can result in additive central nervous system depression. This interaction may lead to excessive sedation, respiratory depression, impaired psychomotor function, and an increased risk of falls or cognitive impairment, particularly in elderly or debilitated patients. Concurrent use may also lower the seizure threshold, especially in patients with predisposing factors."
"Dextromethorphan, a serotonergic agent metabolized by CYP2D6, when combined with cariprazine, a dopamine D3/D2 receptor partial agonist, may increase the risk of serotonin syndrome due to additive serotonergic effects. Cariprazine can inhibit CYP2D6, reducing dextromethorphan clearance and elevating its plasma concentration, leading to enhanced serotonin activity. Clinically, patients may present with altered mental status, autonomic instability, and neuromuscular abnormalities."
"Dextromethorphan inhibits CYP2B6 and CYP2C9, which are involved in valproic acid metabolism. This results in decreased valproic acid clearance, potentially elevating valproic acid serum concentrations and increasing the risk of dose-dependent adverse effects such as hepatotoxicity, thrombocytopenia, and sedation. Concurrent use requires dose adjustment and close monitoring for signs of valproate toxicity."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about DEXTROMETHORPHAN POLISTIREX vs CODEPREX, answered by our medical review team.
DEXTROMETHORPHAN POLISTIREX is a Antitussive that works by Dextromethorphan polistirex is an NMDA receptor antagonist and sigma-1 receptor agonist. It inhibits serotonin reuptake and acts on the brain stem cough center to elevate the threshold for coughing.. CODEPREX is a Antitussive Combination that works by Codeine is a prodrug converted to morphine via CYP2D6; morphine acts as a mu-opioid receptor agonist, while homatropine is an anticholinergic that reduces respiratory secretions.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between DEXTROMETHORPHAN POLISTIREX and CODEPREX depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of DEXTROMETHORPHAN POLISTIREX is: 30-60 mg orally every 12 hours; not to exceed 120 mg in 24 hours.. The standard adult dose of CODEPREX is: Adults: 1 tablet (containing 5 mg hydrocodone and 325 mg acetaminophen) orally every 4-6 hours as needed for pain; maximum 6 tablets per day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between DEXTROMETHORPHAN POLISTIREX and CODEPREX in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. DEXTROMETHORPHAN POLISTIREX is classified as Category C. No well-controlled studies in pregnant women. Animal studies have not shown evidence of fetal harm. Based on limited human data, risk of major congenital malformations is low. Avoi. CODEPREX is classified as Category C. Based on available data, codeine is pregnancy category C. First trimester: Avoid due to possible association with congenital malformations (e.g., cardiovascular defects) from retro. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.