COLYTE
Clinical safety rating
cautionComprehensive clinical and safety monograph for COLYTE (COLYTE).
Colyte is a polyethylene glycol (PEG)-based osmotic laxative that induces diarrhea by retaining water in the gastrointestinal tract via osmotic forces, thereby cleansing the colon.
| Metabolism | Polyethylene glycol is not significantly metabolized and is excreted largely unchanged in feces. |
| Excretion | COLYTE (polyethylene glycol 3350 and electrolytes) is minimally absorbed; <0.1% of the dose is excreted renally. The majority is eliminated unchanged in feces via the gastrointestinal tract, with fecal excretion accounting for >99%. |
| Half-life | Not applicable; systemic absorption is negligible (<0.06%), so a terminal elimination half-life is clinically irrelevant. The gastrointestinal transit time for the solution is approximately 1-3 hours. |
| Protein binding | Not applicable; negligible systemic absorption, so protein binding is clinically irrelevant. |
| Volume of Distribution | Not applicable; negligible systemic absorption, so volume of distribution is clinically irrelevant. |
| Bioavailability | Oral: <0.1% (systemic bioavailability is negligible due to minimal absorption of polyethylene glycol). |
| Onset of Action | Oral: 1-2 hours (onset of bowel evacuation, with maximal effect typically within 1-3 hours). |
| Duration of Action | Oral: Duration of bowel cleansing effect lasts until the colon is evacuated, usually ceasing within 2-6 hours after the last dose. The drug itself is not systemically active. |
| Molecular Weight | 3350 |
4 L oral solution administered as a single dose at a rate of 240 mL every 10 minutes until complete.
| Dosage form | FOR SOLUTION |
| Renal impairment | No dose adjustment required for renal impairment; use with caution in severe renal insufficiency (CrCl <30 mL/min) due to potential electrolyte imbalance. |
| Liver impairment | No specific dose adjustments for hepatic impairment; use with caution in severe hepatic disease. |
| Pediatric use | Pediatric patients (≥6 months): 25-40 mL/kg/hour orally or via nasogastric tube until rectal effluent is clear; maximum 4 L. |
| Geriatric use | No specific dose adjustment; monitor for dehydration and electrolyte disturbances due to reduced renal reserve. |
| 1st trimester | Category C: No adequate studies in humans; animal studies not available or show adverse effects. Use only if clearly needed. |
| 2nd trimester | Category C: No adequate studies in humans; potential risks unknown. Use only if clearly needed. |
| 3rd trimester | Category C: May cause fluid and electrolyte imbalance; use with caution, especially near term. |
Clinical note
Comprehensive clinical and safety monograph for COLYTE (COLYTE).
| Placental transfer | Not well studied; PEG 3350 is a high molecular weight polymer with minimal absorption, suggesting negligible placental transfer, but electrolytes may cross. |
| Breastfeeding | PEG 3350 and electrolytes are minimally absorbed systemically, but safety during breastfeeding has not been established. Use only if clearly needed and monitor infant for diarrhea or electrolyte disturbances. |
| Lactation Rating | L3: Limited data - probably compatible but caution advised. |
| Teratogenic Risk | Category C. No adequate and well-controlled studies in pregnant women. Animal studies have not been conducted. Should be used during pregnancy only if clearly needed. Potential for fetal harm due to maternal dehydration or electrolyte imbalance. |
| Fetal Monitoring | Monitor maternal serum electrolytes (sodium, potassium, chloride, bicarbonate) and renal function during prolonged use. Assess for signs of dehydration, nausea, vomiting, or abdominal distention. Fetal monitoring not specifically required. |
| Fertility Effects | No known effects on fertility. Data not available. |
■ FDA Black Box Warning
None
| Serious Effects |
Gastrointestinal obstructionGastric retentionBowel perforationToxic colitisToxic megacolonIleus
| Precautions | Risk of electrolyte disturbances (especially in patients with renal impairment or those taking medications affecting electrolytes), aspiration risk (use with caution in patients with impaired gag reflex or at risk of regurgitation), serious fluid and electrolyte abnormalities, cardiac arrhythmias, seizures, and serious adverse reactions including ischemic colitis and ulcerative colitis. Use with caution in patients with severe ulcerative colitis, toxic megacolon, or gastrointestinal obstruction. |
| Food/Dietary | Avoid all solid foods during bowel preparation; only clear liquids (e.g., water, clear broth, apple juice, black coffee, clear soda) are permitted. Dairy products, red or purple liquids (which can mimic blood), and alcohol should be avoided. Resume a normal diet only after the procedure. |
| Clinical Pearls | Colyte (PEG-3350 with electrolytes) is used for bowel cleansing prior to colonoscopy. Ensure adequate hydration to prevent electrolyte imbalances. Administer in divided doses; split-dose regimen improves tolerability and cleansing quality. Contraindicated in GI obstruction, gastric retention, bowel perforation, toxic colitis, or megacolon. Monitor for bloating, nausea, and vomiting; slow rate if symptoms occur. |
| Patient Advice | Follow the prescribed dosing schedule exactly; do not skip doses. · Drink the entire solution as directed, typically with a split-dose regimen (half the evening before, half the morning of the procedure). · Stay well-hydrated; drink clear liquids after starting the preparation. · Avoid solid foods; only clear liquids are allowed until after the procedure. · Expect frequent, watery bowel movements; this is necessary for cleansing. · Notify your doctor if you experience severe bloating, vomiting, or signs of dehydration. · Do not take other medications within 1 hour of starting the preparation. |
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