Dutifully Restore Natural Bowel Rhythm with Duphalac
Duphalac (lactulose) is a first-line osmotic laxative of choice for healthcare professionals managing constipation and hepatic encephalopathy. As a synthetic disaccharide, it works through a unique, physiology-respecting mechanism that is not absorbed in the gastrointestinal tract. Its efficacy and well-established safety profile make it a cornerstone therapy for patients requiring predictable and gentle relief, from pediatric to geriatric populations. This expert review details the pharmacological profile, clinical applications, and essential prescribing information for this essential medication.
Features
- Active Pharmaceutical Ingredient: Lactulose (a synthetic disaccharide sugar).
- Pharmacotherapeutic Group: Osmotic laxative, Ammonia detoxicant.
- Available Formulations: Oral solution and syrup, typically at a concentration of 3.35-3.75 g/5ml.
- Mechanism of Action: Functions as an osmotic agent in the colon, drawing water into the bowel lumen to soften stool and stimulate peristalsis. Also serves as a substrate for beneficial colonic bacteria.
- Onset of Action: Full therapeutic effect for constipation typically occurs within 24-48 hours, though it may take up to 72 hours.
- Prescription Status: Available both by prescription and over-the-counter in many regions, depending on strength and local regulations.
Benefits
- Physiological Action: Mimics natural processes by softening stool and enhancing bowel motility without causing harsh stimulant effects or dependency, making it suitable for long-term use.
- Dual Therapeutic Indications: Effectively treats chronic and occasional constipation while also serving as a primary pharmacotherapy for the prevention and treatment of portal-systemic encephalopathy (hepatic encephalopathy) by reducing blood ammonia levels.
- High Safety Profile: Non-systemic, non-absorbable, and non-habit-forming, with a extensive history of safe use in sensitive populations, including infants, pregnant women, and the elderly.
- Prebiotic Effect: Promotes the growth of beneficial gut flora (e.g., Bifidobacteria, Lactobacilli) by acting as a fermentable substrate, thereby supporting overall colonic health and a balanced microbiome.
- Predictable and Gentle Efficacy: Provides reliable relief without sudden urgency or cramping, allowing patients to maintain normal daily activities.
- Versatile Dosing: Flexible dosing regimen allows for precise titration to achieve the desired clinical effect, individualized to each patient’s needs and response.
Common use
Duphalac is primarily indicated for the treatment of constipation. It is used to restore and maintain regular bowel habits in cases of chronic idiopathic constipation, constipation related to immobility, medication-induced constipation (e.g., from opioids), and in patients with irritable bowel syndrome (IBS-C). Its second major indication is in the management and prophylaxis of hepatic encephalopathy (portal-systemic encephalopathy) in patients with chronic liver disease. In this context, it acidifies colonic contents, converting absorbable ammonia (NH3) into the non-absorbable ammonium ion (NH4+), which is then excreted in the feces, thereby reducing blood ammonia levels and improving neuropsychiatric symptoms.
Dosage and direction
Dosage must be individualized based on the indication and patient response. It is crucial to advise patients that the solution can be taken diluted in water, juice, or milk to improve palatability.
- For Constipation:
- Adults & Adolescents: The usual starting dose is 15-30 ml (10-20 g of lactulose) daily. The dose may be increased to 60 ml per day if necessary. Maintenance dose is typically 10-30 ml daily.
- Children: 5 ml daily for children 7-14 years; 2.5-5 ml daily for children 1-6 years. For infants under 1 year, 2.5 ml daily is recommended. Doses can be adjusted to produce 1-2 soft stools per day.
- For Hepatic Encephalopathy:
- Adults: The initial dose is typically 30-50 ml, three to four times daily. The dose is then adjusted to produce 2-3 soft stools per day. The goal is a stool pH of <6.
- Administration: Should be taken orally, ideally at the same time each day (e.g., with breakfast) to establish a routine. Adequate fluid intake (6-8 glasses of water per day) is essential to support its osmotic action.
Precautions
- Electrolyte Monitoring: Long-term use, especially in high doses, should be monitored for potential imbalances in serum electrolytes (e.g., potassium).
- Underlying Pathology: In cases of chronic constipation, the underlying cause should be identified before initiating long-term therapy. If an organic disorder is suspected, appropriate investigations should be performed.
- Diabetic Patients: While the carbohydrate in Duphalac is largely unabsorbed, diabetic patients should be aware it contains galactose and lactose and should monitor blood glucose levels accordingly.
- Elderly and Debilitated Patients: These populations may be more susceptible to electrolyte imbalance and should be monitored, especially if on concomitant diuretics or other medications affecting electrolyte balance.
- Pregnancy and Lactation: Duphalac is considered safe for use during pregnancy and breastfeeding due to its lack of systemic absorption. However, as with all medications, it should be used under medical supervision.
Contraindications
Duphalac is contraindicated in patients with:
- Known hypersensitivity to lactulose or any of the excipients in the formulation.
- Galactosaemia, a rare genetic metabolic disorder.
- Conditions where a rapid increase in intraluminal pressure could be dangerous, such as intestinal obstruction, acute inflammatory bowel disease (e.g., Crohn’s disease, ulcerative colitis during an acute flare), or undiagnosed abdominal pain.
- Appendicitis.
Possible side effect
Most side effects are dose-dependent and related to its pharmacological action. They typically subside with dose adjustment.
- Very Common (≥1/10): Flatulence, abdominal distension, and discomfort (cramping or pain) especially at the beginning of treatment.
- Common (≥1/100 to <1/10): Nausea, vomiting, diarrhea (especially with excessive dosage). Electrolyte imbalance (e.g., hypokalaemia) may occur with prolonged excessive use.
- Uncommon (≥1/1,000 to <1/100): Excessive bowel activity leading to diarrhea and related complications like dehydration.
- Electrolyte disturbances are more likely in patients with renal impairment or those on concomitant medications that affect electrolyte levels.
Drug interaction
- Non-Absorbable Antacids: Concomitant use with antacids (e.g., containing aluminum or magnesium hydroxide) may reduce the acidifying effect of Duphalac in the colon, potentially diminishing its efficacy in treating hepatic encephalopathy. Separate administration by at least 2 hours.
- Other Laxatives: The concurrent use of other laxatives, particularly stimulant types, is not generally recommended and may increase the risk of abdominal cramping and diarrhea.
- Antibiotics: Broad-spectrum antibiotics may reduce the effectiveness of Duphalac for hepatic encephalopathy by eradicating the colonic bacteria necessary to metabolize lactulose.
- Oral Medications: While not systematically documented, the accelerated transit time may theoretically affect the absorption of other orally administered drugs. It is prudent to advise taking other medications at least 2 hours before or after Duphalac.
Missed dose
If a dose is missed, it should be taken as soon as remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped. The patient should not take a double dose to make up for a forgotten one. The regular dosing schedule should be resumed.
Overdose
Overdose will lead to severe diarrhea and abdominal cramps. The primary risk is dehydration and hypovolaemia, along with significant electrolyte losses (particularly potassium). Treatment is entirely supportive and symptomatic: discontinuation of the medication, replacement of fluid and electrolyte losses orally or intravenously, and correction of any resulting electrolyte imbalances. There is no specific antidote.
Storage
- Store below 25°C (77°F). Do not freeze.
- Keep the bottle tightly closed in the original container to protect from light and moisture.
- Keep out of the sight and reach of children.
- Do not use after the expiration date printed on the packaging. The solution may darken slightly over time; this does not affect its potency.
Disclaimer
This information is for educational and professional medical purposes only and does not constitute medical advice. It is not exhaustive. The prescriber or user must always refer to the official local prescribing information (SmPC/package insert) for the most complete, accurate, and up-to-date information regarding indications, dosage, warnings, and precautions. Dosage and administration must be determined by a qualified healthcare professional based on the individual patient’s medical history, current condition, and clinical needs.
Reviews
Duphalac is consistently highly rated in clinical practice and guidelines (e.g., NICE, AGA) for its efficacy, safety, and predictability. Expert consensus reviews praise its role as a first-line osmotic agent for chronic constipation, highlighting its non-habit-forming nature and utility across all age groups. In gastroenterology, it is considered a gold-standard treatment for hepatic encephalopathy, with numerous studies and meta-analyses confirming its superiority over placebo and non-inferiority or superiority compared to other agents like rifaximin, often used in combination therapy. Criticisms from patients occasionally center on initial bloating and gas, as well as its sweet taste, though these are often manageable with dose titration and dilution. Overall, its decades-long presence on the market is a testament to its established position as a reliable and effective therapeutic agent.