Guaifenesin Weight-Based Pediatric Dosing
For children aged 2 years and older, guaifenesin dosing is age-based rather than strictly weight-based, with doses ranging from 100-400 mg every 4 hours (maximum 6 doses per 24 hours) for immediate-release formulations. 1
Age-Based Dosing Recommendations
The pharmacokinetic study in children aged 2-17 years used age-based dosing rather than weight-based calculations, which reflects current OTC monograph recommendations 1:
- Children 2-5 years: 100 mg every 4 hours
- Children 6-11 years: 200 mg every 4 hours
- Adolescents 12-17 years: 200-400 mg every 4 hours
- Maximum: 6 doses in 24 hours for all age groups 1
Extended-Release Formulations
For extended-release guaifenesin tablets (when age-appropriate):
- Dosing interval: Every 12 hours instead of every 4 hours 2
- Doses: 600 mg or 1,200 mg formulations available 2
- Bioequivalence: ER formulations provide equivalent steady-state exposure to corresponding IR doses given every 4 hours 2
Important Clinical Considerations
Guaifenesin demonstrates age-related pharmacokinetic changes: oral clearance and volume of distribution increase with age due to body size, but allometric scaling shows no maturation-related changes in drug handling 1. This supports the use of age-based rather than strict mg/kg dosing.
Food effects: Extended-release formulations show delayed Tmax when taken with food, though total exposure remains equivalent 2. Immediate-release formulations in the pediatric study were administered 2 hours after breakfast 1.
Mechanism of action: Guaifenesin inhibits cough reflex sensitivity in patients with upper respiratory tract infections by either central antitussive effects or peripheral effects through increased sputum volume 3. It is the only legally marketed expectorant in the United States 4.
Common Pitfalls to Avoid
- Do not extrapolate adult weight-based dosing to pediatric patients—use age-based dosing per OTC monograph recommendations 1
- Avoid extended-release formulations in young children who cannot swallow tablets whole
- Multiple daily doses are required with immediate-release formulations to maintain 24-hour therapeutic effect 4
- Guaifenesin has a well-established safety profile in pediatric populations when used at recommended doses 4