CODEPREX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CODEPREX (CODEPREX).
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.
| Metabolism | Codeine undergoes O-demethylation via CYP2D6 to morphine; also N-demethylation to norcodeine via CYP3A4; homatropine is minimally metabolized. |
| Excretion | Renal: 60% as unchanged drug; Hepatic metabolism: 30% (inactive metabolites); Fecal: 10% |
| Half-life | 4-6 hours (prolonged to 10-12 hours in hepatic impairment) |
| Protein binding | 92% (primarily to albumin) |
| Volume of Distribution | 1.5-2.0 L/kg (extensive tissue distribution) |
| Bioavailability | Oral: 70-80% (first-pass metabolism reduces from 100% IV) |
| Onset of Action | Oral: 30-60 minutes; Intravenous: 5-10 minutes |
| Duration of Action | Oral: 4-6 hours; Intravenous: 2-4 hours (shorter duration with repeated dosing due to tolerance) |
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.
| Dosage form | SUSPENSION, EXTENDED RELEASE |
| Renal impairment | Hydrocodone: GFR 30-80 mL/min: no adjustment; GFR 10-29 mL/min: reduce dose by 50% or extend interval to every 8-12 hours; GFR <10 mL/min: use with caution, consider alternative. Acetaminophen: GFR <10 mL/min: extend dosing interval to every 8 hours. |
| Liver impairment | 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. |
| Pediatric use | Not recommended for pediatric use (no safety and efficacy data established). |
| Geriatric use | Start at low end of dosing range (1 tablet every 6 hours) due to increased sensitivity, reduced renal function, and risk of cognitive impairment. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CODEPREX (CODEPREX).
| Breastfeeding | 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. |
| Teratogenic Risk | 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. |
■ 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.
| Serious Effects |
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.
| Precautions | 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. |
| Food/Dietary | Grapefruit juice may inhibit CYP2D6 and reduce codeine conversion to morphine, potentially decreasing efficacy. High-fat meals may delay absorption of codeine. Avoid alcohol. |
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| Fetal Monitoring | Monitor maternal respiratory rate, sedation level, and bowel function. Fetal monitoring for heart rate variability and growth in chronic use. Neonatal monitoring for respiratory depression if used near delivery. Assess umbilical cord gas if used during labor. |
| Fertility Effects | Codeine may transiently affect fertility in males (reduced sperm motility) and females (possible menstrual irregularities) due to opioid effects on hypothalamic-pituitary-gonadal axis. No permanent impairment expected. |
| Clinical Pearls | 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. |
| Patient Advice | 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. |