HALFLYTELY
Clinical safety rating: caution
Comprehensive clinical and safety monograph for HALFLYTELY (HALFLYTELY).
PEG 3350 is an osmotic agent that causes water retention in the colon, leading to bowel evacuation. Electrolytes (sodium sulfate, potassium chloride, magnesium sulfate, sodium bicarbonate) prevent significant electrolyte shifts.
| Metabolism | PEG 3350 is not metabolized; excreted unchanged in feces. Electrolytes are absorbed and excreted renally. |
| Excretion | Primarily fecal elimination of unabsorbed PEG 3350; negligible systemic absorption <0.06%. Electrolytes are excreted renally and fecally. |
| Half-life | Not applicable; PEG 3350 is not significantly absorbed and does not have a systemic half-life. The colon transit time is approximately 1 hour after ingestion. |
| Protein binding | Negligible; <1% binding to plasma proteins due to minimal absorption. |
| Volume of Distribution | Not applicable; remains largely in the gastrointestinal tract. Systemic Vd not measurable. |
| Bioavailability | Oral: <0.06% for PEG 3350; electrolytes are absorbed but not quantified as active drug. |
| Onset of Action | Oral: 1-2 hours for first bowel movement; peak effect 2-3 hours. |
| Duration of Action | Oral: 3-4 hours for bowel cleansing; residual effects may last up to 6 hours. |
Oral: 1 liter (provided as powder for reconstitution) administered at a rate of 240 mL every 10 minutes until rectal effluent is clear or 4 liters total is consumed. Typically given as split-dose: half the volume the evening before and half the morning of colonoscopy.
| Dosage form | FOR SOLUTION, TABLET, DELAYED RELEASE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment (eGFR ≥30 mL/min/1.73m2). Caution in severe renal impairment (eGFR <30 mL/min/1.73m2) due to risk of electrolyte disturbances; consider alternative bowel preparation. |
| Liver impairment | No specific dose adjustment based on Child-Pugh classification. Use with caution in severe hepatic impairment due to potential for electrolyte abnormalities. |
| Pediatric use | Not indicated for pediatric use. Alternative preparations available for pediatric population. |
| Geriatric use | No specific dose adjustment; monitor for dehydration and electrolyte imbalances; ensure adequate hydration during administration. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for HALFLYTELY (HALFLYTELY).
| Breastfeeding | Polyethylene glycol 3350 is not expected to appear in breast milk due to high molecular weight and poor absorption. M/P ratio not applicable. Use with caution due to potential maternal dehydration. |
| Teratogenic Risk | Polyethylene glycol 3350 and electrolytes (HALFLYTELY) are poorly absorbed systemically; no known teratogenic risk in any trimester. However, data are limited. Caution recommended due to dehydration risk from diarrhea. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Gastrointestinal obstruction or ileus","Gastric retention or perforation","Toxic colitis or megacolon","Hypersensitivity to any component of HALFLYTELY"]
| Precautions | ["Risk of mucosal ulcerations in patients with inflammatory bowel disease.","Electrolyte disturbances (hyponatremia, hypokalemia) especially in patients with renal impairment or those taking diuretics.","Cardiac arrhythmias in patients with electrolyte imbalances.","Serious fluid and electrolyte abnormalities may occur in patients with vomiting, diarrhea, or dehydration.","Use with caution in patients with impaired gag reflex, aspiration risk, or unconsciousness.","Risk of Mallory-Weiss tear or esophageal perforation in patients with severe esophagitis or gastric retention."] |
Loading safety data…
| Monitor for signs of dehydration, electrolyte imbalances (sodium, potassium), and renal function. Fetal assessment not routinely required but may be indicated if maternal complications arise. |
| Fertility Effects | No known adverse effects on fertility based on limited human data; animal studies show no impairment at clinically relevant doses. |