MUCINEX
Clinical safety rating: caution
Comprehensive clinical and safety monograph for MUCINEX (MUCINEX).
Guaifenesin is an expectorant that increases respiratory tract fluid secretion and reduces mucus viscosity, facilitating its removal.
| Metabolism | Hepatic metabolism via oxidation and demethylation; metabolites excreted in urine. |
| Excretion | Renal: approximately 50-60% as unchanged drug (guaifenesin) and metabolites; minor biliary/fecal elimination (<10%). |
| Half-life | 1-2 hours (terminal elimination half-life); clinical context: rapid clearance requires frequent dosing to maintain mucolytic effect. |
| Protein binding | Minimal (<10% bound); primarily albumin. |
| Volume of Distribution | Approximately 1.0 L/kg; indicates distribution into total body water and tissues. |
| Bioavailability | Oral: approximately 40-50% due to first-pass metabolism (guaifenesin). |
| Onset of Action | Oral: 30-60 minutes to clinical effect (increased respiratory tract fluid output). |
| Duration of Action | 4-6 hours (oral); clinical note: dosing every 4-6 hours is recommended for sustained effect. |
600 mg orally twice daily (extended-release); for immediate-release: 200 mg orally three times daily or 400 mg orally twice daily.
| Dosage form | TABLET, EXTENDED RELEASE |
| Renal impairment | CrCl <30 mL/min: avoid use or reduce dose (e.g., extended-release: 600 mg once daily); CrCl <10 mL/min: contraindicated. |
| Liver impairment | No specific dosing adjustment recommended; use with caution in severe hepatic impairment (no formal Child-Pugh studies). |
| Pediatric use | Immediate-release: 5-10 mg/kg/day in divided doses every 6-8 hours; maximum 300 mg/day for children <6 years, 600 mg/day for 6-12 years. Extended-release: not recommended for children <12 years. |
| Geriatric use | Start at lower end of dosing range; monitor for adverse effects. No specific dose adjustment beyond renal function consideration. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for MUCINEX (MUCINEX).
| Breastfeeding | Guaifenesin is excreted into breast milk in small amounts. The milk-to-plasma ratio is unknown. It is considered compatible with breastfeeding by the American Academy of Pediatrics due to low oral bioavailability in infants. However, monitor for potential adverse effects such as sedation or gastrointestinal upset in the nursing infant. |
| Teratogenic Risk | Guaifenesin (Mucinex) is generally considered low risk in pregnancy. Animal studies have not shown teratogenic effects, but human data are limited. The FDA classifies it as Category C. First trimester: Avoid if possible due to lack of safety data. Second and third trimesters: Use only if clearly needed, as no evidence of fetal harm exists, but caution is warranted. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to guaifenesin or any component"]
| Precautions | ["Do not use for persistent or chronic cough (e.g., with smoking, asthma, emphysema) unless directed by a doctor","Drink plenty of fluids to help loosen mucus","Do not exceed recommended dosage"] |
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| Fetal Monitoring | No specific maternal or fetal monitoring is routinely required. Clinical monitoring for maternal response and any adverse effects is standard. In cases of overdose, monitor for CNS depression, nausea, vomiting, and renal function. |
| Fertility Effects | No known adverse effects on fertility based on animal studies and clinical experience. Guaifenesin is not associated with reproductive toxicity in available data. |