VICKS FORMULA 44
Clinical safety rating: caution
Comprehensive clinical and safety monograph for VICKS FORMULA 44 (VICKS FORMULA 44).
VICKS FORMULA 44 contains dextromethorphan (NMDA receptor antagonist and sigma-1 receptor agonist; suppresses cough by acting on the medullary cough center) and doxylamine (first-generation antihistamine; H1-receptor antagonist; anticholinergic and sedative effects).
| Metabolism | Dextromethorphan is metabolized by CYP2D6 to dextrorphan (active metabolite). Doxylamine is metabolized by CYP2C9 and CYP2C19. |
| Excretion | Renal excretion of unchanged drug and metabolites (dextromethorphan and doxylamine): dextromethorphan is extensively metabolized; <10% excreted unchanged. Doxylamine: ~60% excreted renally as unchanged and metabolites. |
| Half-life | Dextromethorphan: 3-6 hours (extensive metabolizers), up to 24 hours (poor metabolizers); doxylamine: 10-12 hours. Clinically, half-life may be prolonged in elderly, hepatic impairment, or CYP2D6 poor metabolizers. |
| Protein binding | Dextromethorphan: ~45-60% bound to plasma proteins (albumin and alpha-1-acid glycoprotein); doxylamine: ~60-70% bound to plasma proteins. |
| Volume of Distribution | Dextromethorphan: Vd ~5-7 L/kg (extensive distribution, including CNS); doxylamine: Vd ~4-7 L/kg (large distribution due to lipophilicity). |
| Bioavailability | Oral: Dextromethorphan bioavailability ~11% (extensive first-pass metabolism); doxylamine bioavailability ~70-80% (moderate first-pass). |
| Onset of Action | Oral: Dextromethorphan antitussive effect within 15-30 minutes; doxylamine sedative effect within 30 minutes. Peak plasma levels for dextromethorphan at 2-2.5 hours; doxylamine at 2-3 hours. |
| Duration of Action | Dextromethorphan: antitussive effects last 3-6 hours; doxylamine: antihistamine/sedative effects last 4-6 hours. Clinical notes: doxylamine may cause residual sedation. |
VICKS FORMULA 44 is a combination product containing dextromethorphan (cough suppressant) and doxylamine (antihistamine). The typical adult dose is 30 mg dextromethorphan/6.25 mg doxylamine (15 mL) orally every 6 hours as needed for cough and cold symptoms, not to exceed 4 doses per 24 hours.
| Dosage form | SYRUP |
| Renal impairment | For GFR 30-89 mL/min: No adjustment required. For GFR <30 mL/min: Dextromethorphan may accumulate; consider reducing dose to 15 mg dextromethorphan/3.125 mg doxylamine (7.5 mL) every 6 hours. Doxylamine is not significantly renally cleared but may cause increased sedation in severe renal impairment. |
| Liver impairment | Child-Pugh Class A: No adjustment. Child-Pugh Class B: Reduce dose to 15 mg dextromethorphan/3.125 mg doxylamine (7.5 mL) every 6 hours due to decreased clearance of dextromethorphan. Child-Pugh Class C: Avoid use due to potential accumulation and increased sedation risk. |
| Pediatric use | Children <12 years: Not recommended due to lack of safety and efficacy data. Children ≥12 years: Same as adult dose (30 mg dextromethorphan/6.25 mg doxylamine, 15 mL) orally every 6 hours as needed, not to exceed 4 doses daily. |
| Geriatric use | Patients ≥65 years: Initial dose reduction recommended due to increased sensitivity to anticholinergic effects and sedation. Start at 15 mg dextromethorphan/3.125 mg doxylamine (7.5 mL) orally every 6 hours; increase to full dose if tolerated. Monitor for confusion, urinary retention, and falls. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for VICKS FORMULA 44 (VICKS FORMULA 44).
| Breastfeeding | Dextromethorphan: Excreted in breast milk in small amounts; considered compatible with breastfeeding. Doxylamine: Excreted in breast milk; may cause sedation in infants. Acetaminophen: Low levels in breast milk; considered safe. Phenylephrine: Excreted in breast milk; systemic absorption minimal but may reduce milk production. M/P ratio: Not established for the combination; individual M/P ratios: acetaminophen ~0.9, others unknown. |
| Teratogenic Risk | Dextromethorphan: No adequate studies in pregnant women; animal studies have not shown fetal harm. Doxylamine: Approved for nausea/vomiting in pregnancy (doxylamine/pyridoxine combination); evidence does not suggest increased risk of major malformations. Acetaminophen: Low risk when used as directed; chronic high doses may be associated with adverse outcomes. Phenylephrine: Avoid during first trimester; possible association with gastroschisis and minor malformations. Overall, Vicks Formula 44 contains multiple active ingredients; use only if clearly needed and with caution. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to any component","Concurrent use of MAO inhibitors or within 14 days","Pregnancy (especially first trimester) due to doxylamine's anticholinergic effects"]
| Precautions | ["Do not use with any other product containing dextromethorphan","Avoid alcohol","May cause marked drowsiness; avoid driving or hazardous activities","Use caution in patients with chronic cough (e.g., asthma, COPD), cough with excessive phlegm, or liver disease"] |
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| Fetal Monitoring | Monitor for fetal growth and development with ultrasound if used for prolonged periods. Assess maternal blood pressure, heart rate, and signs of sedation. In neonates, monitor for respiratory depression if maternal use near term. No specific fetal monitoring required for short-term use. |
| Fertility Effects | No known effects on fertility from dextromethorphan, doxylamine, acetaminophen, or phenylephrine at therapeutic doses. Acetaminophen may be associated with reduced fecundity in some studies; clinical significance unclear. |