DEXBROMPHENIRAMINE MALEATE AND PSEUDOEPHEDRINE SULFATE
Clinical safety rating: safe
MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.
Dexbrompheniramine is a first-generation antihistamine that competitively antagonizes histamine at H1 receptors, reducing allergic symptoms. Pseudoephedrine is a sympathomimetic amine that directly stimulates alpha-adrenergic receptors, causing vasoconstriction and decongestion.
| Metabolism | Dexbrompheniramine is primarily metabolized by CYP3A4 and CYP2D6. Pseudoephedrine is partially metabolized by N-demethylation and oxidative deamination, with about 43-96% excreted unchanged in urine. |
| Excretion | Dexbrompheniramine and its metabolites are primarily excreted renally (approximately 80-85% of a dose as unchanged drug and metabolites). Pseudophedrine is largely excreted unchanged in urine (70-90%) via glomerular filtration and tubular secretion; the remainder is hepatically metabolized. Biliary/fecal elimination is minimal (<5%). |
| Half-life | Dexbrompheniramine: terminal elimination half-life is approximately 12-25 hours in adults. Pseudophedrine: terminal elimination half-life is about 5-8 hours in adults with normal renal function; it is prolonged in patients with renal impairment. |
| Protein binding | Dexbrompheniramine: approximately 90% bound to plasma proteins. Pseudophedrine: negligible protein binding (<10%). |
| Volume of Distribution | Dexbrompheniramine: Vd is approximately 3-5 L/kg, indicating extensive tissue distribution. Pseudophedrine: Vd is approximately 2.5-3.5 L/kg. |
| Bioavailability | Both components are well absorbed orally. Dexbrompheniramine: oral bioavailability is approximately 60-80%. Pseudophedrine: oral bioavailability is about 90-100%. |
| Onset of Action | Oral: Dexbrompheniramine's antihistamine effects begin within 1-2 hours. Pseudophedrine's decongestant effect begins within 30-60 minutes. |
| Duration of Action | Dexbrompheniramine: duration of antihistamine effect is up to 24 hours, allowing once-daily dosing. Pseudophedrine: immediate-release formulations provide decongestant effect for 4-6 hours; extended-release formulations last 12-24 hours. |
| Molecular Weight | 435.5 |
| Action Class | Antihistamine and decongestant combination |
1 tablet (each containing dexchlorpheniramine maleate 2 mg/pseudoephedrine sulfate 120 mg) orally every 12 hours; maximum 2 tablets per day.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | GFR 30-50 mL/min: extend interval to every 12-24 hours; GFR <30 mL/min: contraindicated due to risk of accumulation. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50% or extend interval; Child-Pugh C: contraindicated. |
| Pediatric use | Not recommended for children under 12 years; for ages 12+: same as adult dosing. |
| Geriatric use | Start at lowest effective dose (e.g., 1 tablet daily) due to increased sensitivity to anticholinergic effects and risk of confusion; monitor for urinary retention and hypertension. |
| 1st trimester | Avoid use during first trimester unless clearly needed; limited human data, potential risk of vascular disruptions. |
| 2nd trimester | Use only if benefit outweighs risk; may cause uterine contractions from pseudoephedrine. |
| 3rd trimester | Avoid near term; pseudoephedrine may cause uterine artery vasoconstriction and reduce placental perfusion. |
Clinical note
MAOIs can cause hypertensive crisis Can cause insomnia and tachycardia.
| FDA category | Animal |
| Placental transfer | Both components cross the placenta; pseudoephedrine has documented transfer in animal studies. |
| Breastfeeding | Excreted into breast milk in small amounts; pseudoephedrine may reduce milk production. Use with caution in nursing mothers; monitor infant for irritability and sleep disturbances. |
■ FDA Black Box Warning
None.
| Common Effects | Insomnia |
| Serious Effects | Hypertension, Tachycardia, Arrhythmias, Stroke, Myocardial infarction, Seizures, Psychosis, Urinary retention, Angle-closure glaucoma |
Severe hypertensionCoronary artery diseaseNarrow-angle glaucomaUrinary retentionConcurrent MAOI therapySevere renal impairment
| Precautions | Cardiovascular effects: hypertension, palpitations, arrhythmias; use cautiously in cardiovascular disease, CNS stimulation: nervousness, dizziness, insomnia; avoid in severe hypertension or coronary artery disease, Anticholinergic effects: urinary retention, blurred vision; caution in glaucoma or prostatic hypertrophy, Drug interactions: MAO inhibitors, sympathomimetics, antihypertensives |
| Food/Dietary | Avoid high-tyramine foods (e.g., aged cheese, cured meats, fermented products) if taking MAOIs concurrently. Pseudoephedrine's pressor effect may be enhanced by caffeine; limit caffeinated beverages. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Avoid; limited human data, but theoretical risk of antihistamine-related malformations. Second and third trimesters: Caution; pseudoephedrine may reduce uterine blood flow and cause fetal tachycardia. |
| Fetal Monitoring | Monitor maternal blood pressure and heart rate due to pseudoephedrine. In late pregnancy, monitor fetal heart rate and uterine activity if used near term. |
| Fertility Effects | No known effects on fertility. However, antihistamines may interfere with ovulation in animal studies; human data limited. |
| Clinical Pearls | Dexbrompheniramine is an alkylamine antihistamine with sedative effects; pseudoephedrine is a sympathomimetic decongestant. Avoid in severe hypertension, coronary artery disease, or MAOI use. Monitor for CNS stimulation (insomnia, nervousness) from pseudoephedrine. Antihistamines may exacerbate urinary retention in BPH or narrow-angle glaucoma. Combination therapy is common in OTC cold products. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Avoid alcohol and other CNS depressants due to additive sedation. · Do not crush or chew extended-release formulations. · Discontinue and consult prescriber if palpitations, dizziness, or tremor occur. · Not recommended for children under 6 years without prescriber approval. · Use caution when driving or operating machinery until response is known. |