SEMPREX-D
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SEMPREX-D (SEMPREX-D).
SEMPREX-D combines acrivastine, a histamine H1 receptor antagonist, and pseudoephedrine, a sympathomimetic amine vasoconstrictor. Acrivastine blocks peripheral histamine-mediated effects, while pseudoephedrine constricts nasal blood vessels to reduce congestion.
| Metabolism | Acrivastine: Partially metabolized by carboxylesterases and CYP450 isozymes (minor). Pseudoephedrine: Minimally metabolized by N-demethylation in the liver. |
| Excretion | Renal (approx. 60% as unchanged drug and metabolites), biliary/fecal (approx. 40%). |
| Half-life | Terminal elimination half-life is approximately 8-12 hours, allowing twice-daily dosing. |
| Protein binding | Approximately 85% bound to plasma proteins, mainly albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Apparent Vd is about 3-4 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability of pseudoephedrine is about 100%; brompheniramine is approximately 50-70% due to first-pass metabolism. |
| Onset of Action | Oral: 15-30 minutes for decongestant effect; antihistamine effect begins within 1 hour. |
| Duration of Action | Decongestant effect lasts up to 12 hours; antihistamine effect persists for approximately 12-24 hours, supporting twice-daily administration. |
1 capsule orally every 12 hours; each capsule contains acrivastine 8 mg and pseudoephedrine 60 mg.
| Dosage form | CAPSULE |
| Renal impairment | Contraindicated in severe renal impairment (GFR <30 mL/min). For GFR 30-50 mL/min: reduce frequency to every 24 hours. For GFR >50 mL/min: no adjustment needed. |
| Liver impairment | Avoid use in severe hepatic impairment (Child-Pugh class C). For Child-Pugh class A or B: use with caution, no specific dose adjustment recommended; monitor for adverse effects. |
| Pediatric use | Not recommended for children under 12 years. For children ≥12 years: same as adult dosing (1 capsule every 12 hours). |
| Geriatric use | Use with caution; may be more sensitive to anticholinergic and sympathomimetic effects. Consider starting with lower dose or extended dosing interval. Avoid in patients with significant cardiovascular disease, hypertension, or prostatic hyperplasia. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SEMPREX-D (SEMPREX-D).
| Breastfeeding | Pseudoephedrine and dexchlorpheniramine are excreted into breast milk. Pseudoephedrine milk-to-plasma ratio approx 2.5-3.5. May reduce milk production and cause irritability or sedation in infant. Use with caution; monitor infant for CNS stimulation. Avoid high doses or prolonged use. |
| Teratogenic Risk | No adequate studies in pregnant women. First trimester: known fetal risks associated with sympathomimetics (e.g., reduced uteroplacental blood flow, potential for neural tube defects at high doses). Second trimester: possible association with gastroschisis from pseudoephedrine. Third trimester: risk of preterm labor, fetal tachycardia, and intrauterine growth restriction due to vasoconstriction. Avoid use during pregnancy unless benefit outweighs risk. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to any component","Severe hypertension or coronary artery disease","Concurrent use or within 14 days of MAOIs","Narrow-angle glaucoma","Urinary retention","Severe hepatic or renal impairment"]
| Precautions | ["Cardiovascular effects: Pseudoephedrine may cause hypertension, palpitations, and arrhythmias.","CNS stimulation: Insomnia, nervousness, dizziness, or tremors.","Urinary retention: Caution in patients with prostatic hypertrophy.","Increased intraocular pressure: Avoid in narrow-angle glaucoma.","Severe hepatic or renal impairment: Use with caution.","Hypertension: Contraindicated in severe hypertension or coronary artery disease."] |
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| Fetal Monitoring | Monitor maternal blood pressure, heart rate, and fetal heart rate. Assess for signs of preterm labor. Consider fetal growth ultrasound if used long-term. Evaluate for maternal CNS stimulation or cardiovascular adverse effects. |
| Fertility Effects | Limited data. Sympathomimetics may theoretically impair uterine blood flow and ovulatory function. No established effect on female or male fertility. Use not recommended in patients attempting conception without medical guidance. |