DISOPHROL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DISOPHROL (DISOPHROL).
Disophrol is a combination of dexbrompheniramine, a first-generation antihistamine that blocks H1 receptors, and pseudoephedrine, a sympathomimetic amine that stimulates alpha-adrenergic receptors causing vasoconstriction.
| Metabolism | Dexbrompheniramine is metabolized in the liver primarily via CYP450 enzymes; pseudoephedrine is partially metabolized in the liver by N-demethylation and excreted largely unchanged in urine. |
| Excretion | Renal excretion of unchanged drug and metabolites; approximately 60-70% of a dose eliminated in urine as unchanged drug and glucuronide conjugates, with <10% in feces. |
| Half-life | Terminal elimination half-life is 3-4 hours in adults; in renal impairment, half-life may be prolonged up to 8-12 hours requiring dose adjustment. |
| Protein binding | Approximately 50-60% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 1.5-2.5 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability is about 70-80% due to first-pass metabolism. |
| Onset of Action | Oral: Onset of decongestant effect occurs within 15-30 minutes; antihistaminic effect within 30-60 minutes. |
| Duration of Action | Duration of action is 4-6 hours for decongestant effect; antihistaminic effects last up to 6-8 hours. Clinical use typically every 4-6 hours. |
1 tablet (6 mg dexbrompheniramine maleate / 60 mg pseudoephedrine sulfate) orally every 4-6 hours; not to exceed 4 tablets in 24 hours.
| Dosage form | TABLET |
| Renal impairment | GFR 30-50 mL/min: administer every 6-8 hours. GFR 15-29 mL/min: administer every 12 hours. GFR <15 mL/min: not recommended. |
| Liver impairment | Child-Pugh Class A: no adjustment. Child-Pugh Class B: use with caution, reduce dose frequency. Child-Pugh Class C: contraindicated. |
| Pediatric use | Children 6-11 years: 1/2 tablet (3 mg dexbrompheniramine / 30 mg pseudoephedrine) orally every 4-6 hours, max 2 tablets per day. Children <6 years: not recommended. |
| Geriatric use | Initiate with 1/2 tablet every 6-8 hours; monitor for anticholinergic effects and hypertension; avoid in patients >65 years due to increased risk of adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DISOPHROL (DISOPHROL).
| Breastfeeding | DISOPHROL is excreted into breast milk. Dexchlorpheniramine: Present in low levels, M/P ratio not established; may cause irritability and drowsiness in infants. Pseudoephedrine: Excreted into breast milk with M/P ratio of approximately 2.6-3.5; may cause infant irritability and decreased milk production. Use caution and monitor infant for excessive drowsiness or irritability. |
| Teratogenic Risk | DISOPHROL (dexchlorpheniramine/pseudoephedrine) is classified as FDA Pregnancy Category C. First trimester: Case reports suggest a possible small increased risk of gastroschisis with antihistamine use, but data are limited; pseudoephedrine may be associated with a small risk of gastroschisis and hemifacial microsomia. Second and third trimesters: No specific fetal risks have been clearly established; pseudoephedrine may cause fetal tachycardia and decreased uterine blood flow at high doses. Avoid in third trimester due to potential for uterine contraction inhibition and neonatal respiratory depression from antihistamines. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Severe hypertension","Coronary artery disease","Concurrent use of MAO inhibitors or within 14 days of such therapy","Narrow-angle glaucoma","Urinary retention","Severe renal impairment","Hypersensitivity to any component"]
| Precautions | ["Cardiovascular effects: may cause hypertension, palpitations, arrhythmias","Central nervous system stimulation: may cause insomnia, dizziness, tremor","Urinary retention: use with caution in patients with BPH or urinary obstruction","Increased intraocular pressure: avoid in narrow-angle glaucoma","Elderly patients: more sensitive to anticholinergic and cardiovascular effects"] |
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| Fetal Monitoring | Monitor blood pressure and heart rate in mother due to pseudoephedrine's sympathomimetic effects. Fetal monitoring for tachycardia if pseudoephedrine is used near term. Assess for signs of uterine irritability or preterm labor. Observe newborn for respiratory depression or sedation if used near delivery. |
| Fertility Effects | No specific data on fertility effects. Antihistamines may theoretically affect ovulation via anticholinergic effects, but significance is unknown. Pseudoephedrine may reduce uterine blood flow but impact on conception is not established. |