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). |
| Molecular Weight | Pseudoephedrine: 165.23 Da; Dextromethorphan: 271.40 Da |
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 | Avoid: Contains pseudoephedrine which may be associated with gastroschisis and small intestinal atresia; dextromethorphan safety in first trimester is uncertain. |
| 2nd trimester | Use with caution: Limited data suggest pseudoephedrine and dextromethorphan are relatively safe in second trimester, but avoid prolonged use. |
| 3rd trimester | Avoid: Pseudoephedrine may cause uterine vasoconstriction and reduce placental perfusion; near term, dextromethorphan may rarely cause neonatal respiratory depression. |
Clinical note
Comprehensive clinical and safety monograph for DRIXORAL (DRIXORAL).
| Placental transfer | Both pseudoephedrine and dextromethorphan cross the placenta. Pseudoephedrine has known placental transfer; dextromethorphan transfer is limited but documented. |
| Breastfeeding | Pseudoephedrine is excreted into breast milk in small amounts; it may reduce milk supply due to vasoconstriction. Dextromethorphan is excreted in negligible amounts. Avoid use in breastfeeding if possible, or use as a single dose and monitor infant for irritability and poor feeding. |
■ FDA Black Box Warning
None
| Serious Effects |
Severe hypertensionCoronary artery diseaseConcurrent use of MAO inhibitors or within 14 daysNarrow-angle glaucomaUrinary retentionSevere hepatic impairment
| 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. |
| Food/Dietary | Avoid consuming alcohol while taking Drixoral due to additive CNS depressant effects. No specific food interactions are known; however, a low-sodium diet may be beneficial if hypertension is a concern due to pseudoephedrine. |
Loading safety data…
| Lactation Rating | L3 - Moderately Safe |
| 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. |
| 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. |
| Clinical Pearls | Drixoral is a combination of dexbrompheniramine (an antihistamine) and pseudoephedrine (a decongestant). Avoid use in patients with severe hypertension, coronary artery disease, or MAOI use. Anticholinergic effects may precipitate angle-closure glaucoma, urinary retention, or thyroid storm. Sedation from dexbrompheniramine can impair driving; pseudoephedrine may cause CNS stimulation. Use with caution in elderly, prostatic hypertrophy, or bladder neck obstruction. |
| Patient Advice | Do not drive or operate heavy machinery until you know how this drug affects you, as it may cause drowsiness or dizziness. · Avoid alcohol, as it can increase sedation and side effects. · Do not exceed recommended dosage to avoid serious cardiovascular effects like rapid heart rate or elevated blood pressure. · Consult a doctor before use if you have high blood pressure, heart disease, diabetes, thyroid disorders, or difficulty urinating. · Do not take if you are currently taking or have taken MAO inhibitors within the last 14 days. · May cause dry mouth, so use sugarless gum or candy; if persistent, notify your physician. |