DRIXORAL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DRIXORAL (DRIXORAL).
Drixoral is a combination product containing dexbrompheniramine maleate, a first-generation antihistamine that competitively antagonizes histamine at H1 receptor sites, and pseudoephedrine sulfate, a sympathomimetic amine that acts as a decongestant by stimulating alpha-adrenergic receptors in the respiratory tract mucosa, causing vasoconstriction and reducing nasal congestion.
| Metabolism | Dexbrompheniramine: Hepatic metabolism primarily via CYP450 enzymes (CYP2D6 and CYP3A4). Pseudoephedrine: Hepatic metabolism via oxidative N-demethylation and glucuronidation, with some renal elimination of unchanged drug. |
| Excretion | Drixoral contains dexbrompheniramine (renal: 30-50% unchanged, rest metabolites) and pseudoephedrine (renal: 70-90% unchanged, pH-dependent). |
| Half-life | Dexbrompheniramine: 12-15h (prolonged in renal impairment). Pseudoephedrine: 5-8h (alkaline urine slows elimination, half-life up to 20h). |
| Protein binding | Dexbrompheniramine: 72-96% bound to albumin. Pseudoephedrine: negligible (<5% bound, mainly to α1-acid glycoprotein). |
| Volume of Distribution | Dexbrompheniramine: 5-10 L/kg (extensive tissue distribution). Pseudoephedrine: 2-3 L/kg (distributes into body water). |
| Bioavailability | Oral: Dexbrompheniramine: oral bioavailability 50-70% (first-pass effect). Pseudoephedrine: oral bioavailability >90% (minimal first-pass). |
| Onset of Action | Oral: 15-30 min for pseudoephedrine (decongestant); 1-2h for dexbrompheniramine (antihistamine). |
| Duration of Action | Oral: Pseudoephedrine: 4-6h (extended-release 12h). Dexbrompheniramine: 6-8h (extended-release up to 12h). |
One pseudoephedrine 60 mg and dexbrompheniramine 2 mg tablet orally every 12 hours; maximum 2 tablets per 24 hours.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | Contraindicated in severe renal impairment (eGFR <30 mL/min/1.73 m²). In moderate impairment (eGFR 30-59), use with caution; consider extended dosing interval every 24 hours. |
| Liver impairment | Contraindicated in severe hepatic impairment (Child-Pugh class C). In moderate impairment (Child-Pugh class B), use with caution; decrease dose by 50% or extend interval. No adjustment needed in mild disease (Child-Pugh class A). |
| Pediatric use | Not recommended for children under 6 years. For ages 6-12: half a tablet (pseudoephedrine 30 mg/dexbrompheniramine 1 mg) orally every 12 hours. For ages 12 and older: adult dose. |
| Geriatric use | In patients ≥65 years, start with half the adult dose (one half-tablet every 12 hours) due to increased sensitivity and higher risk of anticholinergic effects, sedation, and cardiovascular events. Monitor renal function and discontinue if adverse effects occur. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DRIXORAL (DRIXORAL).
| Breastfeeding | Limited data; both components excrete into breast milk. M/P ratio unknown. Potential for infant irritability, tachycardia. Use caution; antihistamines may reduce milk supply. Avoid in nursing mothers when possible. |
| Teratogenic Risk | Drixoral (dexbrompheniramine/pseudoephedrine) has limited human data. First trimester: potential minor malformation risk from antihistamines. Second/third trimester: pseudoephedrine may cause uterine vasoconstriction and fetal hypoxia. Avoid in third trimester due to risk of premature labor and fetal tachycardia. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to any component. Patients taking monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping MAOIs. Severe hypertension, coronary artery disease, narrow-angle glaucoma, urinary retention, or severe hepatic/renal impairment. Children under 12 years of age (for the specific formulation).
| Precautions | May cause drowsiness and impair mental alertness. Avoid alcohol and other CNS depressants. Use with caution in patients with hypertension, cardiovascular disease, diabetes, glaucoma, hyperthyroidism, prostate hypertrophy, or urinary retention. Prolonged use may lead to rebound congestion. Do not exceed recommended dosage. |
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| Fetal Monitoring |
| Monitor maternal blood pressure and heart rate; assess fetal heart rate for tachycardia. In third trimester, monitor uterine activity for preterm contractions. Consider growth scans if used chronically. |
| Fertility Effects | No specific data; pseudoephedrine may impair uterine blood flow theoretically affecting implantation. Antihistamines may have anticholinergic effects on cervical mucus, but clinical significance unknown. |