polyethylene glycol
Brand: MiraLAX, Glycolax
Prototype Drug
Drug Class: laxative (osmotic)
Drug Family: GI agent
Subclass: non-absorbed osmotic agent
Organ Systems: gastrointestinal
Mechanism of Action
Large polymer that is not absorbed or metabolized; retains water osmotically in GI lumen softening stool; no systemic absorption.
intestinal lumen (osmotic retention)
Indications
- constipation (chronic and occasional)
- bowel prep before colonoscopy (high-dose GoLYTELY)
Contraindications
- bowel obstruction
- known allergy
Adverse Effects
Common
- bloating
- flatulence
- nausea
- diarrhea (high dose)
Serious
- electrolyte disturbances (high-dose bowel prep)
Pharmacokinetics (ADME)
| Absorption | not absorbed systemically |
| Distribution | GI lumen |
| Metabolism | not metabolized |
| Excretion | fecal |
| Half-life | not applicable |
| Onset | 1-3 days (constipation) |
| Peak | variable |
| Duration | variable |
| Protein Binding | none |
| Vd | none |
Nursing Considerations
- Dissolve in 8 oz water, juice, coffee, or other beverage — odorless and tasteless
- Onset: 1-3 days for constipation (not acute)
- High-dose (GoLYTELY): 4L for colonoscopy prep — monitor elderly for dehydration
- OTC dose: 17 g daily — long-term use generally safe
Clinical Pearls
- Non-absorbed: minimal systemic effects — one of the safest laxatives for long-term use
- GoLYTELY (high-dose PEG + electrolytes) for bowel prep: maintains electrolyte balance unlike plain PEG
Safety Profile
Pregnancy safe
Lactation generally-safe
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.