1. Clinical Overview
Lactitol is a synthetic disaccharide sugar alcohol derived from lactose. It is a hyperosmotic laxative used primarily for the treatment of constipation and hepatic encephalopathy. In the Indian context, it is widely available as a syrup (66.67% w/v, equivalent to 10g/15ml) and is considered a safe, well-tolerated option for chronic constipation, especially in the elderly and patients with hepatic disorders. It works by drawing water into the bowel lumen, softening stools and increasing bowel motility.
| Onset | Duration | Bioavailability |
|---|---|---|
| 24 to 48 hours for laxative effect; up to 48-72 hours for full effect in hepatic encephalopathy. | Dose-dependent, typically 12-24 hours per dose. | <0.5% (Minimal systemic absorption; acts locally in the colon). |
2. Mechanism of Action
Lactitol is a poorly absorbed disaccharide. Its primary mechanism is osmotic. It passes unchanged through the small intestine to the colon, where it draws water into the bowel lumen by osmosis, increasing stool water content, softening the stool, and stimulating peristalsis. In hepatic encephalopathy, colonic bacteria ferment lactitol to organic acids (primarily acetic and lactic acid), which acidify colonic contents. This acidification traps ammonia (NH3) as ammonium ions (NH4+), which are poorly absorbed, and also promotes the growth of non-urease-producing bacteria, thereby reducing ammonia production and absorption.
3. Indications & Uses
- Chronic Idiopathic Constipation
- Hepatic Encephalopathy (prophylaxis and treatment)
4. Dosage & Administration
Adult Dosage: Constipation: 10-20g (15-30ml of 66.67% w/v syrup) daily, preferably with a meal. Adjust to individual response. Hepatic Encephalopathy: Initial dose 0.5-0.7g/kg body weight/day in divided doses (2-3 times) to produce 2-3 soft stools per day. Typical range: 30-60ml (20-40g) in divided doses.
Administration: For oral administration only. The syrup (66.67% w/v) can be taken directly or mixed with water, juice, or soft food. For hepatic encephalopathy, it is often administered via nasogastric tube after dilution. Administer with meals to improve tolerability and integrate with digestive process. Ensure adequate fluid intake (1.5-2 liters daily).
5. Side Effects
Common side effects may include:
- Flatulence
- Abdominal distension
- Borborygmi (stomach rumbling)
- Nausea (especially at high initial doses)
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Non-potassium-sparing Diuretics (e.g., Furosemide, Hydrochlorothiazide) | Increased risk of hypokalemia due to potential diarrhea-induced potassium loss. | Moderate |
| Corticosteroids (e.g., Prednisolone) | Additive risk of hypokalemia. | Moderate |
| Digoxin | Hypokalemia can potentiate digoxin toxicity. | Major |
| Other Laxatives | Additive effect, increasing risk of diarrhea and electrolyte disturbances. | Moderate |
| Antibiotics (broad-spectrum, e.g., Neomycin) | May reduce efficacy in hepatic encephalopathy by altering colonic flora needed for lactitol fermentation. Sometimes used together under supervision. | Moderate |
7. Patient Counselling
- DO take the prescribed dose, usually with a meal.
- DO mix the syrup with water or juice if you find the sweetness too strong.
- DO maintain adequate fluid intake (at least 8 glasses of water daily).
- DO inform your doctor if you have diabetes or galactosemia.
- DONT take more than the prescribed dose to avoid severe diarrhea.
- DONT use it if you have severe abdominal pain, nausea, or vomiting.
- DONT use it as a long-term solution without consulting your doctor for chronic constipation.
8. Toxicology & Storage
Overdose: Symptoms are an extension of side effects: Severe, watery diarrhea leading to dehydration, hypovolemia, electrolyte disturbances (hypokalemia, hyponatremia), abdominal cramps, and weakness.
Storage: Store below 30°C. Protect from light and moisture. Keep the bottle tightly closed. Do not freeze. Keep out of reach of children. Shelf life is typically 24-36 months from manufacture.