GLYCOLAX
Clinical safety rating
cautionComprehensive clinical and safety monograph for GLYCOLAX (GLYCOLAX).
Osmotic laxative. Polyethylene glycol (PEG) increases intraluminal water volume in the colon by osmosis, promoting stool passage and relieving constipation.
| Metabolism | Not metabolized; excreted unchanged in feces. |
| Excretion | Minimally absorbed; excreted primarily unchanged in feces via osmotic action. Renal excretion negligible (<0.2% absorbed dose). |
| Half-life | Not applicable due to negligible systemic absorption; local colonic transit time approximately 2-4 hours. |
| Protein binding | Not bound (polyethylene glycol not bound to plasma proteins). |
| Volume of Distribution | Not applicable due to minimal absorption; if absorbed, distributes largely in extracellular fluid; Vd negligible. |
| Bioavailability | Oral: <0.2% (systemic absorption negligible); rectal: minimal systemic absorption. |
| Onset of Action | Oral: 6-12 hours; rectal: 2-5 minutes (for constipation), 30-60 minutes (for bowel evacuation). |
| Duration of Action | Oral: 24-48 hours (bowel movement within 24 hours for constipation); rectal: 2-4 hours for evacuation. |
| Molecular Weight | 3350 |
17 g (1 heaping tablespoon) dissolved in 4-8 ounces of liquid once daily, orally.
| Dosage form | FOR SOLUTION |
| Renal impairment | No dose adjustment required, but use with caution in patients with renal impairment due to risk of electrolyte disturbances. |
| Liver impairment | No dose adjustment required; use standard dosing for patients with hepatic impairment. |
| Pediatric use | For children 2-11 years: 8.5 g (1/2 heaping tablespoon) dissolved in 4-8 ounces of liquid once daily; for children 12 years and older: same as adult dosing. |
| Geriatric use | Use with caution due to increased risk of electrolyte disturbances and dehydration; consider lower starting dose (e.g., 8.5 g once daily) and monitor electrolytes and fluid status. |
| 1st trimester | Generally considered safe; minimal systemic absorption. No teratogenic effects reported in animal studies. |
| 2nd trimester | Safe for use; no known adverse fetal effects. |
| 3rd trimester | Safe, including use as a bowel preparation before delivery; no known harm to fetus. |
Clinical note
Comprehensive clinical and safety monograph for GLYCOLAX (GLYCOLAX).
| Placental transfer | Minimal to no placental transfer due to high molecular weight (3350 Da) and poor lipid solubility. It is not significantly absorbed systemically after oral administration. |
| Breastfeeding | Excretion into breast milk is minimal due to high molecular weight and poor absorption. No adverse effects in nursing infants have been reported. Use caution if infant has electrolyte abnormalities or impaired renal function. |
| Lactation Rating | L1 (Safe) |
| Teratogenic Risk | Polyethylene glycol 3350 (GlycoLax) has no known teratogenic effects. Animal studies show no fetal harm. Human data are limited but no increased risk of major congenital malformations has been reported. Use in all trimesters is considered low risk. |
| Fetal Monitoring | No specific monitoring required beyond routine prenatal care. Monitor for electrolyte disturbances if used chronically or in large doses. |
| Fertility Effects | No known effects on fertility in animal or human studies. Polyethylene glycol is not systemically absorbed and does not impact reproductive function. |
■ FDA Black Box Warning
None
| Serious Effects |
Bowel obstructionPerforationToxic megacolonGastric retentionKnown hypersensitivity to polyethylene glycol
| Precautions | Use beyond 1 week may cause dependence; caution in patients with bowel obstruction, ileus, or gastrointestinal perforation; risk of electrolyte disturbances with prolonged use. |
| Food/Dietary | No significant food interactions. May be taken with or without food. Avoid concurrent use with high-fiber foods if bloating occurs, as this may exacerbate symptoms. |
| Clinical Pearls | GLYCOLAX (polyethylene glycol 3350) is an osmotic laxative. Onset of action is 24-48 hours. Not for acute relief of constipation; use for chronic constipation. May take 2-4 days for full effect. Avoid in intestinal obstruction or perforation. Dose can be adjusted to achieve soft stools. Can be mixed with any non-carbonated beverage. |
| Patient Advice | Take once daily, preferably in the morning, mixed in 4-8 ounces of liquid. · Effect may take 2-4 days; do not use for immediate relief. · Do not exceed 7 days of use without consulting a doctor. · Drink plenty of fluids while using this medication. · Notify your doctor if you have severe stomach pain, nausea, vomiting, or if you notice blood in your stool. · Keep out of reach of children. |
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