Usage
- Polyethylene Glycol (PEG) 3350 is primarily prescribed for the treatment of occasional constipation. It is also used for bowel cleansing prior to colonoscopies or other bowel procedures.
- Pharmacological Classification: Osmotic laxative.
- Mechanism of Action: PEG 3350 works by increasing the amount of water in the intestinal tract. This softens the stool and promotes bowel movements.
Alternate Names
- PEG 3350
- Polyethylene glycol electrolyte solution
- Brand Names: MiraLAX, GlycoLax, GaviLAX, ClearLax, Lax-A-Day, PEG-3350 with Electrolytes
How It Works
- Pharmacodynamics: PEG 3350 exerts its laxative effect by retaining water within the intestinal lumen through its osmotic properties. The increased water content softens the stool, increases stool volume, and stimulates peristalsis, leading to more frequent bowel movements.
- Pharmacokinetics: PEG 3350 is minimally absorbed from the gastrointestinal tract. The small amount that is absorbed is excreted unchanged in the urine. It is not metabolized by CYP enzymes. Elimination is primarily through fecal excretion.
- Mode of Action: PEG 3350 is a large molecule that exerts its action through its high molecular weight and its ability to form hydrogen bonds with water. This prevents water reabsorption from the gut, thereby increasing stool water content and volume. It does not bind to receptors, inhibit enzymes, or modulate neurotransmitters directly.
- Elimination Pathways: Primarily fecal excretion; minimal renal excretion of the unabsorbed drug.
Dosage
Standard Dosage
Adults:
- 17 grams (approximately one capful or packet) orally once daily, dissolved in 4 to 8 ounces of liquid.
- Maximum dosage: Not to exceed 7 days of continuous use without consulting a doctor.
Children:
- For children 2-16 years of age: 0.4 g/kg/day orally, initially. Dosage may be adjusted in the range of 0.2 g/kg/day to 1.8 g/kg/day. Maximum dose is 17 g/day.
- For infants and children younger than 2 years: Consult a pediatrician for appropriate dosing guidance.
Special Cases:
- Elderly Patients: Start with the standard adult dosage. Careful monitoring is recommended, as elderly patients may be more susceptible to side effects, especially dehydration.
- Patients with Renal Impairment: No specific dosage adjustment is generally necessary.
- Patients with Hepatic Dysfunction: No specific dosage adjustment is generally necessary.
- Patients with Comorbid Conditions: Caution advised for patients with electrolyte imbalances, heart problems, and gastrointestinal disorders. Individualized dosage adjustments may be needed.
Clinical Use Cases
- Intubation/Surgical Procedures/Mechanical Ventilation/ICU Use/Emergency Situations: PEG is not typically used in these settings. Other laxatives or bowel management strategies are usually preferred.
Dosage Adjustments
Dose adjustments based on patient-specific factors are generally not necessary, except for children and patients with specific comorbidities as mentioned above.
Side Effects
Common Side Effects
- Bloating
- Gas
- Abdominal discomfort or cramping
- Nausea
- Diarrhea
Rare but Serious Side Effects
- Allergic reactions (e.g., hives, itching, rash, difficulty breathing, swelling of the face, lips, tongue, or throat)
- Severe or bloody diarrhea
- Rectal bleeding
Long-Term Effects
- Electrolyte imbalances (with prolonged or excessive use)
- Laxative dependence (with prolonged or excessive use)
Adverse Drug Reactions (ADR)
- Severe allergic reactions (anaphylaxis)
- Severe dehydration
- Ischemic colitis
Contraindications
- Known or suspected bowel obstruction
- Gastrointestinal perforation
- Toxic megacolon
- Hypersensitivity to polyethylene glycol
Drug Interactions
- May reduce the absorption of other orally administered medications if taken within two hours of each other.
- May interact with diuretics, increasing the risk of electrolyte imbalances.
- May interact with other laxatives, potentially increasing the risk of side effects.
- No known interactions with CYP450 enzymes.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: Category C (US FDA). Studies in animals have shown some adverse effects on the fetus. There are no adequate and well-controlled studies in humans. PEG 3350 should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding: No specific recommendations for breastfeeding women. Minimal amounts are expected to be excreted in breast milk due to poor systemic absorption.
Drug Profile Summary
- Mechanism of Action: Osmotic laxative that retains water in the bowel, softening stool and promoting bowel movements.
- Side Effects: Bloating, gas, abdominal discomfort, nausea, diarrhea. Rarely, allergic reactions, severe diarrhea, rectal bleeding.
- Contraindications: Bowel obstruction, GI perforation, toxic megacolon, hypersensitivity to PEG.
- Drug Interactions: May affect absorption of other oral medications. May interact with diuretics and other laxatives.
- Pregnancy & Breastfeeding: Use with caution during pregnancy. No specific recommendations for breastfeeding.
- Dosage: Adults: 17 grams orally once daily. Children: 0.4 g/kg/day.
- Monitoring Parameters: Monitor for signs of dehydration and electrolyte imbalances, especially in elderly patients.
Popular Combinations
- PEG 3350 is often combined with electrolytes for bowel preparation before colonoscopies.
Precautions
- Monitor fluid and electrolyte balance, especially in elderly patients.
- Discontinue use if rectal bleeding occurs.
- Avoid use for more than 7 days without consulting a doctor.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Polyethylene Glycol?
A: For adults and children 17 years and older, the typical dose is 17 grams (one capful or packet) mixed with 4 to 8 ounces of liquid once daily. For children aged 2 to 16, dosing should be based on weight (0.4 g/kg/day initially).
Q2: How long does it take for Polyethylene Glycol to work?
A: It typically produces a bowel movement within 1 to 3 days.
Q3: What are the common side effects of Polyethylene Glycol?
A: Common side effects include bloating, gas, abdominal discomfort, nausea, and diarrhea.
Q4: Can pregnant or breastfeeding women take Polyethylene Glycol?
A: Pregnant women should consult with their doctor before using PEG 3350. While small amounts may pass into breast milk, it’s generally considered safe for breastfeeding mothers.
A: Prolonged and excessive use can lead to laxative dependence. It’s important to use PEG 3350 as directed and only for occasional constipation.
Q6: What should I do if I experience severe diarrhea while taking Polyethylene Glycol?
A: Discontinue use and contact your healthcare provider immediately.
Q7: Can I take other medications with Polyethylene Glycol?
A: It’s best to avoid taking other medications within two hours of taking PEG 3350, as it may interfere with their absorption.
Q8: Are there any dietary restrictions while taking Polyethylene Glycol?
A: Generally, no specific dietary restrictions are necessary. However, maintaining adequate fluid intake is essential.
Q9: Can Polyethylene Glycol be used for long-term treatment of constipation?
A: It’s intended for occasional use. Long-term use should only be under the guidance of a healthcare professional.
Q10: What should I do if I miss a dose of Polyethylene Glycol?
A: Take the missed dose as soon as you remember. If it’s close to the time for your next dose, skip the missed dose and continue with your regular schedule. Do not double the dose to catch up.
