Guaifenesin

Approved Indications:

• Symptomatic relief of productive cough due to upper respiratory tract infections (URTIs), such as the common cold.
• Bronchitis with associated mucus hypersecretion.
• Chronic obstructive pulmonary disease (COPD) exacerbations where mucus clearance is beneficial.
• Pneumonia adjunct therapy to facilitate expectoration of secretions.

Clinically Accepted Off-Label Uses:

• Relief of chest congestion associated with influenza.
• Facilitation of mucus clearance in patients with cystic fibrosis (as an adjunct to airway clearance therapy).
• Symptomatic relief of post-nasal drip with productive cough.

Adults & Adolescents (>12 years):

• Immediate-Release Tablets or Syrup: 200–400 mg orally every 4 hours as needed.
• Maximum Daily Dose: 2,400 mg.

Children (6–12 years):

• 100–200 mg orally every 4 hours as needed.
• Maximum Daily Dose: 1,200 mg.

Children (2–6 years):

• 50–100 mg orally every 4 hours as needed.
• Maximum Daily Dose: 600 mg.

Children <2 years:

• Use only under medical supervision.

Special Populations:

• Renal impairment: No dosage adjustment required.
• Hepatic impairment: Use with caution; monitor for adverse effects if taken chronically.

Administration Notes:

• Take with a full glass of water to enhance mucolytic effect.
• Swallow tablets whole; do not crush or chew.
• Do not exceed recommended dose or frequency.

Guaifenesin works as an expectorant by increasing the volume and reducing the viscosity of respiratory tract secretions. At the cellular level, it stimulates vagal nerve endings in the gastric mucosa, which in turn increases hydration of respiratory tract secretions through reflex stimulation of respiratory glands. The result is thinner mucus that is easier to expectorate, facilitating clearance from the airways and improving cough efficacy.

• Absorption: Rapidly absorbed from the gastrointestinal tract.
• Bioavailability: Approximately 60–70% after oral administration.
• Distribution: Widely distributed in body fluids; does not significantly cross the blood-brain barrier.
• Protein Binding: Minimal (~1%).
• Metabolism: Extensively metabolized in the liver to inactive metabolites.
• Elimination: Primarily renal excretion as metabolites; <5% excreted unchanged.
• Half-Life: 1 hour (range 0.8–1.5 hours).
• Onset of Action: Symptomatic relief generally observed within 30 minutes to 1 hour after oral administration.

• Pregnancy: Category C — animal studies show no significant teratogenic effects; human data limited. Use only if clearly needed.
• Lactation: Guaifenesin is excreted in small amounts in breast milk; considered compatible with breastfeeding at recommended doses, but caution is advised.
• Note: Data in pregnancy and lactation are limited; avoid high doses or prolonged use.

• Primary Class: Expectorant
• Subclass: Symptomatic relief agent for productive cough

• Known hypersensitivity to guaifenesin or any formulation excipients.
• Severe renal or hepatic impairment if prolonged high-dose therapy is required (caution advised).

• High-risk patients:
• Patients with chronic respiratory diseases requiring careful monitoring of mucus clearance.
• Individuals with history of kidney or liver impairment.
• Serious risks:
• Rare hypersensitivity reactions including rash, urticaria, or anaphylaxis.
• Monitoring:
• Discontinue if persistent cough with fever or purulent sputum develops, as it may indicate a serious underlying condition.
• Other precautions:
• Ensure adequate hydration to enhance mucolytic effect.
• Avoid combining with other cough medications containing guaifenesin without medical guidance.

Common:

• Nausea, vomiting
• Headache
• Dizziness
• Mild gastrointestinal discomfort

Rare/Serious:

• Allergic reactions (rash, pruritus, urticaria)
• Hypersensitivity or anaphylactic reactions (very rare)
• Gastrointestinal upset at high doses

Onset & Dose Dependence:

• Typically mild and transient; dose-dependent gastrointestinal effects may occur with excessive intake.

• Drug-Drug: Minimal clinically significant interactions.
• May enhance effect of other mucolytics or antitussive drugs; use caution to avoid overlapping therapy.
• Drug-Food: No known interactions; taking with food may reduce mild gastrointestinal upset.
• Drug-Alcohol: No significant interaction; alcohol does not affect guaifenesin’s efficacy.
• Enzyme Systems: Not significantly metabolized by CYP450 enzymes; low risk of metabolic interactions.

• Current guidelines: Recommended as a first-line expectorant for symptomatic relief of productive cough in URTIs.
• Safety updates: Emphasis on proper hydration to improve effectiveness.
• Pediatric use: Guidelines clarify safe age-appropriate dosing and caution in children under 2 years.
• Combination therapy: Often used in combination with decongestants or antitussives for multi-symptom relief, but caution against overlapping guaifenesin-containing products.

• Store at 20°C–25°C (room temperature).
• Protect from moisture and direct sunlight.
• Keep container tightly closed.
• Do not freeze.
• Keep out of reach of children.