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. |
| Molecular Weight | 553.56 |
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 | Avoid due to anticholinergic effects and potential teratogenicity; limited human data show possible association with malformations. |
| 2nd trimester | Use only if benefit outweighs risk; may cause anticholinergic side effects. |
| 3rd trimester | Avoid near term due to risk of neonatal respiratory depression, irritability, and anticholinergic effects. |
Clinical note
Comprehensive clinical and safety monograph for DISOPHROL (DISOPHROL).
| Placental transfer | Crosses placenta; extent not fully quantified but expected due to low molecular weight and lipophilicity. |
| Breastfeeding | Excreted into breast milk in small amounts; monitor infant for irritability, drowsiness, and anticholinergic effects. Use with caution, especially in premature or ill infants. |
■ FDA Black Box Warning
None.
| Serious Effects |
Hypersensitivity to any componentNarrow-angle glaucomaObstructive uropathySevere hypertensionCoronary artery diseaseConcurrent MAOI therapy
| 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 |
| Food/Dietary | Avoid consuming alcohol while taking Disophrol. Caffeine may increase restlessness and insomnia. There is no specific food interaction, but taking with food may reduce gastrointestinal upset. |
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| Lactation Rating |
| L3 |
| 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. |
| 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. |
| Clinical Pearls | Disophrol combines an antihistamine (dexbrompheniramine) and a decongestant (pseudoephedrine). Avoid in patients with hypertension, coronary artery disease, or hyperthyroidism due to pseudoephedrine's sympathomimetic effects. Monitor for anticholinergic side effects (drowsiness, dry mouth) from the antihistamine component. Use with caution in glaucoma, urinary retention, and prostatic hypertrophy. |
| Patient Advice | Take this medication as prescribed; do not exceed recommended dose due to risk of serious side effects. · Avoid alcohol and other CNS depressants as they may increase drowsiness. · Do not take with other medications containing decongestants or antihistamines. · Notify your doctor if you have high blood pressure, heart disease, glaucoma, or difficulty urinating. · May cause drowsiness; avoid driving or operating heavy machinery until you know how it affects you. |