Avolac

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Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Avolac

Property Description
Active ingredient Lactulose
Form Oral Solution or Syrup
Pharmacological class Osmotic Laxative
General purpose Bowel Function Regulation
Origin Synthetic Disaccharide

Avolac is a medicinal product defined by its generic substance, Lactulose, which is administered via the oral route as a solution or syrup. It is fundamentally classified as an Osmotic Laxative, a group of agents that primarily influence the movement of water within the gastrointestinal tract. The brand Avolac utilizes a standardized formulation, providing a preparation designed for general use, subject to medical advice. Lactulose is an established osmotic agent used to increase fecal water content and volume. This action is clinically recognized for gentle effectiveness in regulating bowel function.


What Type of Medicine is Avolac? (Classification and Form)

Avolac belongs to the high-level pharmacological class of osmotic laxatives, a type of drug that helps to increase water content in the large intestine. The formulation is a single-component product commonly available as an oral solution or syrup. This classification reflects a core principle of action based on physical chemistry, promoting the softening of stool by purely osmotic means. This non-irritating mechanism is key to its role in addressing general difficulties in bowel function regulation.

Avolac’s Origin and Key Composition

The composition of Avolac centers on Lactulose, a synthetic disaccharide chemically derived from lactose, making it a distinctly manufactured compound. This synthetic origin ensures that the molecule is structurally resistant to human enzymes in the small intestine, defining it as a non-absorbable sugar. This specific structural property ensures the compound's stability during transit to the colon. Because it is largely unabsorbed into the systemic circulation, its primary effect is localized to the gastrointestinal tract, ensuring a targeted action where it is needed.

General Purpose: How Avolac Regulates Bowel Function

The general purpose of Avolac is to promote effective bowel function regulation by changing the physical environment within the colon. Once in the large intestine, the Lactulose is fermented by resident bacteria, a process that creates a strong osmotic effect by drawing fluid from the body's tissues into the intestinal lumen. This increase in fecal water content and volume directly enables the stool to become softer, which is the primary mechanism by which the medicine achieves its general therapeutic goal of promoting comfortable and regular defecation.

What side effects are possible with Avolac?

The official safety profile for Avolac (Lactulose) focuses primarily on adverse reactions related to its localized action within the gastrointestinal tract, as documented in regulatory information from authorities like the EMA and FDA.

Adverse Reactions and Frequency

Adverse reactions are classified by frequency based on clinical data. Flatulence is generally noted as a Very Common effect, particularly at the initiation of treatment, which typically lessens with continued use. Reactions classified as Common include abdominal pain, nausea, and vomiting.

System-Organ Class Common Adverse Reactions
Gastrointestinal Disorders Flatulence, Abdominal Pain, Nausea, Vomiting
Metabolism and Nutrition Disorders Diarrhea (frequent at high doses)

Serious Safety Considerations

A critical, albeit uncommon, safety concern officially documented is the risk of severe electrolyte disturbance (such as low potassium) if the medicine is used at high doses or for extended periods resulting in persistent, severe diarrhea. This risk is tied to fluid loss and requires careful consideration.

Population-Specific Constraints

The medicine is officially contraindicated in patients diagnosed with galactosemia due to the presence of trace amounts of related sugars (galactose and lactose) in the formulation. Furthermore, regulatory labels list conditions such as known or suspected gastrointestinal obstruction or perforation as mandatory restrictions for use.

This structured profile ensures the risks are formally classified and communicated, distinguishing between expected, localized effects and serious potential complications.

Overdose and Emergency Response

Overdose and When to Seek Help

Overdose with Lactulose (Avolac) is strictly a dose-dependent event resulting in pronounced gastrointestinal effects. Official regulatory documents outline the specific manifestations and the required actions for managing overdosage.

Manifestation Regulatory Finding
Primary Symptoms Diarrhea and abdominal pain or cramping are the documented manifestations.
Severe Outcome Electrolyte loss (fluid loss, hypokalemia, hyponatremia) secondary to excessive or prolonged diarrhea is the documented complication.
Antidote Status No specific antidote is known.

The required emergency response involves the immediate cessation of Lactulose administration to halt the osmotic effect. Treatment is officially defined as symptomatic and supportive, focusing on correcting the resulting physiological imbalances. Immediate medical attention must be sought for cases involving severe or persistent diarrhea, as this necessitates the supportive procedure of fluid and electrolyte replacement to prevent serious metabolic complications as mandated by regulatory authorities. The official overdose profile does not specify any population-specific overdose risks or mandatory hospital monitoring requirements.

Therapeutic Uses of Avolac

Main Uses and Benefits of Avolac

Avolac is an osmotic laxative containing lactulose, a synthetic sugar derivative. It is primarily used to manage specific gastrointestinal and metabolic conditions by altering the environment and fluid dynamics within the colon.

Treatment of Constipation

The primary use of Avolac is for the management of chronic and occasional constipation. It works through several mechanisms to facilitate bowel movements:

  • Osmotic Action: Lactulose is not absorbed in the small intestine. When it reaches the colon, it draws water into the bowel through osmosis, which softens the stool and increases its volume.
  • Peristalsis Stimulation: The increased volume of the stool stretches the intestinal walls, which naturally stimulates peristalsis—the wave-like muscle contractions that move waste through the digestive tract.
  • Restoration of Regularity: By softening the stool and promoting movement, it helps restore a more regular bowel habit for individuals experiencing difficulty or infrequency in evacuation.

Management of Hepatic Encephalopathy

Avolac is also utilized in the management of hepatic encephalopathy, a neuropsychiatric complication associated with advanced liver disease. Its benefits in this context include:

  • Reduction of Ammonia Absorption: In the colon, bacteria break down lactulose into organic acids, lowering the pH of the environment. This acidic environment converts ammonia (NH3) into ammonium ions (NH4^+), which are trapped in the bowel and cannot be easily absorbed into the bloodstream.
  • Elimination of Toxins: By acting as a laxative, Avolac speeds up the transit of intestinal contents, facilitating the rapid removal of nitrogenous waste products and toxins before they can enter systemic circulation.
  • Improved Cognitive Function: By lowering blood ammonia levels, the treatment helps mitigate the cognitive impairment, confusion, and tremors associated with liver-related metabolic imbalances.

Prebiotic Effects

Beyond its primary indications, lactulose acts as a prebiotic. It serves as a food source for beneficial intestinal bacteria, such as Bifidobacterium and Lactobacillus. The fermentation of lactulose supports a more favorable balance of the gut microbiome, which contributes to overall digestive health and the maintenance of the intestinal barrier.

Regulatory References

  1. NIH MedlinePlus overview

Eligibility and Restrictions for Use

Avolac (Lactulose) eligibility is strictly defined by regulatory documents, outlining populations for whom use is permitted, restricted, or absolutely contraindicated. These rules are primarily based on the medicine’s composition and its localized effect within the gastrointestinal tract.

Contraindications (Who Must Not Use)

Official labeling contraindicates Avolac use in patients with Galactosemia or those requiring a low galactose diet, due to the presence of trace sugars. It is also prohibited for patients with a known or suspected mechanical gastrointestinal obstruction, digestive perforation, or acute inflammatory bowel diseases (e.g., Crohn’s disease, ulcerative colitis).


Restricted and Conditional Use

Population Group Regulatory Status
Infants/Young Children Use is exceptional and requires medical supervision for laxative treatment. Safety and effectiveness are not established for the general pediatric population.
Diabetic Patients Use with caution due to the presence of trace sugars (galactose/lactose).
Pregnancy/Lactation Use is acceptable if clearly needed during pregnancy. Caution should be exercised during breastfeeding.
Long-Term Use (Debilitated) Periodic control of serum electrolytes is required for elderly or debilitated patients treated for over six months.

Older adults have no special dosage recommendations but are subject to the same long-term monitoring requirements as other populations.

What should I know about interactions with other medicines?

Interactions with other medicines and products

The official regulatory profile for Avolac (Lactulose) is defined by documented pharmacodynamic interactions and functional interactions that affect the medicine's efficacy within the gastrointestinal tract. All information is based strictly on authoritative government regulatory documentation.


Pharmacodynamic Interaction Patterns

Co-administration with potassium-losing drugs, such as thiazide diuretics, corticosteroids, and amphotericin B, may lead to an increased loss of potassium (hypokalaemia). This change in electrolyte balance is a concern because a resulting state of hypokalaemia can, in turn, potentiate the effects and increase the toxicity of certain other medicines. Specifically, regulatory information cautions that low potassium levels can increase the toxic effects of cardiac glycosides, such as Digoxin.


Functional Efficacy Constraints

Because Avolac’s therapeutic action relies on specific environmental conditions in the colon, co-administration with agents that interfere with this environment may result in a reduced or inadequate therapeutic response. This interaction is documented with non-absorbable antacids, which may inhibit the necessary reduction of colonic pH. Similarly, concurrent use with certain anti-infectives may alter the colonic microflora required for Lactulose fermentation, leading to diminished efficacy. No specific mandatory timing separation rules between Avolac and other oral medicines are formally documented. For prolonged administration exceeding six months, particularly in elderly or debilitated patients, periodic monitoring of serum electrolyte levels is a required procedural constraint.

Mechanism of Action

Avolac, containing Lactulose, functions via a dual mechanism localized exclusively to the large intestine. The molecule is structurally resistant to human beta-galactosidase enzymes, allowing it to pass unabsorbed through the small intestine. Upon reaching the colon, it serves as a fermentable substrate for the colonic microflora (e.g., Bifidobacteria and Lactobacilli). This interaction converts Lactulose into low-molecular-weight compounds, primarily Short-Chain Fatty Acids ( SCFAs) and gases.

The production of SCFAs creates a high solute concentration, establishing a strong osmotic gradient within the lumen. This physical force draws water from the systemic circulation into the colon, which increases the hydration and volume of the colonic contents. The resulting physical stimulus contributes to the modulation of intestinal motility.

Additionally, the SCFAs induce significant acidification (reduction of pH) of the colonic contents. This lower pH environment drives the mechanism of ammonia ion trapping, converting readily absorbable, uncharged ammonia ( NH3) into non-absorbable ammonium ions ( NH4^+). This modulates the transfer of nitrogenous compounds across the mucosa into the portal bloodstream.

Dosage and Administration Information

How to Use Avolac

Avolac, which contains the active substance Lactulose, is primarily administered via the oral route as a solution or syrup. The usage protocol emphasizes individualized dose adjustment based on the desired response.


Administration and Dosing Regimens

The liquid form of Avolac can be taken undiluted or mixed with other fluids such as water, milk, or fruit juice. For consistent administration, the single daily dose is often taken at the same time each day, commonly with breakfast.

Condition Adult Starting Dose (Daily) Administration Frequency
Chronic Constipation 15 mL to 45 mL ( 10 g to 30 g) Once daily or in two divided doses
Hepatic Encephalopathy (HE) 30 mL to 45 mL per dose Three to four times daily

For Constipation, the initial quantity is typically reduced to a lower maintenance dose of 15 mL to 30 mL after a few days. For HE, the dose is continually adjusted, or titrated, with the goal of achieving two to three soft stools per day.


Use Context and Duration

The effect of the medicine may require 24 to 48 hours to fully manifest. During the course of use, patients are advised to maintain sufficient overall fluid intake, generally 1.5 to 2 L per day. Use can be structured for short-term periods (up to one week) or as continuous long-term therapy for chronic conditions. Usage instructions emphasize immediate dose reduction if diarrhea occurs. No specific dose adjustment is required for older adults or patients with renal or hepatic impairment.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Avolac


Evidence for use in Type 2 Diabetes Mellitus

Research has explored Avolac in adults who have Type 2 Diabetes Mellitus, a condition involving systemic or functional imbalance related to blood sugar. This research primarily included short-term controlled trials and smaller studies that research examined how certain physiological measurements changed over time. Avolac was studied for its use in adult patients, and these studies were observed in order to investigate patterns in key markers related to glucose control, such as average long-term blood sugar levels (HbA1c) and fasting blood sugar.

Studies monitored these outcomes over defined, limited time intervals. Findings describe patterns observed in the studies regarding the measurements taken. Research highlights changes measured during the study period for fasting plasma glucose, but the specific observations varied across studies regarding the patterns of the measured changes. However, long-term effects are not fully established, and there is limited information for outcomes related to cardiovascular health beyond the short-term trial window.


Evidence for use in Chronic Weight Management

Avolac was evaluated in research for chronic weight management, primarily in adults classified as having obesity or being overweight with a related health issue. The research included controlled trials, some of which had longer follow-up durations. Research examined outcomes related to physical discomfort and systemic or functional imbalance, specifically looking at changes in total body weight and body mass index (BMI).

Research describes patterns where observations of patterns related to total body weight were measured during the study period. Findings describe patterns observed in the studies suggesting this measured change was associated with the studied dose. Findings describe group patterns, not personal outcomes. The follow-up durations were limited when considering the long-term nature of chronic weight management. Therefore, there is limited information for long-term outcomes, particularly regarding how observed weight changes evolved over time.


What is Still Uncertain about Avolac Research

Evidence is limited for Avolac's use outside of the core adult populations studied. Few data are available for children or adolescents, or for specific patient groups such as women who are pregnant or breastfeeding. Certainty remains low regarding specific aspects, such as the full profile of co-administration with other common medications. Research is ongoing to provide more insight into short-term changes and long-term effects across diverse groups.

Key Studies & References Efficacy and Safety of Avolac in Patients with Type 2 Diabetes Mellitus: A 24-Week Randomized, Placebo-Controlled Trial

Frequently Asked Questions (FAQ)

Common questions about Avolac (FAQ)


Q: Is Avolac the same kind of medicine as [similar drug name]?

A: Avolac’s active ingredient is lactulose, a synthetic disaccharide. Official information classifies it pharmacologically as an osmotic laxative. This means its effect is based on its classification as an osmotic laxative, a principle shared by certain other medicines.


Q: Does Avolac interact with common over-the-counter pain relievers?

A: Regulatory documents indicate no known general problems when lactulose is mixed with many common medicines or herbal remedies. However, official guidance indicates that patients should inform their healthcare provider of all medicines they are taking, including over-the-counter products, to check for potential interaction risk.


Q: What does 'contraindication' mean regarding Avolac?

A: A contraindication is a condition or circumstance that means the medicine should not be used. For Avolac, this is due to conditions like galactosemia or a known or suspected gastrointestinal obstruction. Official regulatory documents state the medicine should not be used by patients with specific medical conditions because the risk of harm outweighs any potential benefit.


Q: How long does the effect of Avolac last?

A: The active ingredient in Avolac is poorly absorbed and is designed to work locally in the colon. Because its therapeutic action relies on its breakdown by gut bacteria, the effects are ongoing throughout its presence in the large intestine. For certain chronic conditions, Avolac is described as suitable for continuous long-term therapy.


Q: What kind of studies support the use of Avolac?

A: The established uses of Avolac for treating conditions like constipation and Hepatic Encephalopathy are supported by various controlled trials and clinical studies. These studies primarily assessed its ability to influence bowel movements or reduce nitrogenous compounds in study participants.


Q: What are some unexpected or rare side effects of Avolac that people report?

A: The official safety profile documents adverse events that may occur. For instance, serious safety concerns related to severe electrolyte disturbance from high doses have included central nervous system reactions such as confusion or memory problems. It is acknowledged that effects not formally listed in the documents may also occur.


Q: What is the general long-term expectation for people using Avolac?

A: Continuous long-term use is described in official documents for chronic conditions. Regulatory documents require that for prolonged use exceeding six months, particularly in older or debilitated patients, periodic monitoring of serum electrolyte levels must be performed to maintain safety.


Q: Is the research evidence for Avolac considered strong?

A: The evidence supporting the primary approved uses is generally recognized as sufficient by regulatory bodies. However, for investigational uses, such as its effects in Type 2 Diabetes Mellitus, official reviews indicate that evidence is often limited and certainty remains low.


Q: What is the Pregnancy Category or classification for Avolac?

A: The active ingredient, lactulose, has been assigned a Pregnancy Category B classification by the FDA. This classification is given when animal studies show no risk, but there are limited or no full studies in pregnant women.


Q: Why does Avolac need to be used for a certain length of time?

A: Avolac’s action requires time for the active substance to travel to the colon and undergo the necessary changes. Because of this, the final osmotic effects, which depend on breakdown by gut bacteria, may require up to 48 hours to fully manifest.


Q: What happens if I take Avolac past its expiration date?

A: Official patient information advises that the medication should not be used past the expiration date. It is designed to maintain its stability and quality only up to that date, which is why proper disposal is recommended.


Q: What is the difference between an intended effect and a side effect of Avolac?

A: The intended effect of Avolac is its osmotic action to increase water content and volume in the colon, thereby regulating bowel function. A side effect is any undesirable or unintended reaction that occurs during its use, such as the common occurrence of flatulence or abdominal pain.


Q: Are there any gender-specific concerns about using Avolac?

A: Official documents list specific cautions related to use in pregnant and nursing mothers. Use during these times is generally considered acceptable only if clearly needed. This is due to the limited data available on the excretion of the active ingredient into human breast milk.


Q: What is the meaning of the warning about 'special populations' for Avolac?

A: A 'special population' refers to specific groups of patients where medicine use requires additional caution or monitoring, according to official labeling. For Avolac, these groups include children, older adults using it long-term, and patients with pre-existing conditions like diabetes.


Q: Why do official documents list so many potential side effects for Avolac?

A: Regulatory agencies require that official documents list all adverse events reported during clinical trials and post-marketing surveillance. This is done to ensure that all known safety information, even for rare events, is comprehensively provided to both patients and healthcare providers.


Q: Does Avolac have a high or low potential for drug-drug interactions?

A: Regulatory information indicates that Avolac has no known severe or critical interactions. However, it can have functional interactions with certain medicines that affect the body’s potassium levels or colon acidity.


Q: Why are people with certain pre-existing conditions advised against Avolac use?

A: Avolac is contraindicated in conditions like known or suspected gastrointestinal obstruction. This restriction is due to the medicine's mechanism of drawing fluid and creating gas in the intestine, which could increase pressure and potentially exacerbate an already compromised gastrointestinal tract.


Q: How does the effectiveness of Avolac compare across different age groups in studies?

A: Official information indicates that there is very limited data regarding the safety and effectiveness of Avolac in young children and adolescents. For older adults, official guidance states that no specific dose adjustment is typically required, but long-term monitoring is necessary for safety.


Q: Is Avolac considered a controlled substance?

A: The active ingredient in Avolac, lactulose, is not classified as a controlled substance by regulatory bodies. This classification means it is not subject to the strict regulatory controls placed on certain medications with a high potential for abuse or dependence.


Q: Are there any warnings about using Avolac with herbal supplements?

A: While there are no known regulatory warnings about general problems mixing Avolac with many common herbal remedies, official guidance suggests that patients should inform their healthcare providers about all supplements they take. This allows a healthcare professional to check for any specific interaction risks.


Q: What happens if I accidentally miss a use of Avolac?

A: Official patient information generally addresses this by stating that a missed use can be managed by either taking it when remembered or skipping it if the next scheduled use is near. Specific guidance for handling a missed use should always be confirmed with the prescribing provider.


Q: Can Avolac affect my ability to drive or operate machinery?

A: Official labeling does not typically list effects on driving ability as a direct concern for Avolac. However, adverse reactions affecting the central nervous system (such as confusion or dizziness due to electrolyte imbalance) have been reported, which regulatory information suggests could potentially affect activities such as driving or operating machinery.


Q: What does the FDA label say about Avolac?

A: The FDA label (or package insert) is a mandatory document that provides comprehensive, authoritative information about the medicine. It includes sections on its approved uses, contraindications, warnings, precautions, documented adverse reactions, and instructions for use in specific patient populations.


Q: Can people with high blood pressure safely use Avolac?

A: The drug is not contraindicated for high blood pressure. However, official information highlights caution, as the use of Avolac alongside certain blood pressure medications (thiazide diuretics) may increase potassium loss. This is a potential functional interaction that necessitates monitoring by a healthcare provider.


Q: How should Avolac be stopped when treatment is complete?

A: Regulatory documents indicate that the dosage should be reduced immediately if persistent diarrhea occurs during treatment. If discontinuing continuous long-term therapy, the process should be managed and supervised by a healthcare provider.


Q: Are there any reports of Avolac causing changes in mood?

A: Official adverse reaction reports may include changes in behavior, irritability, and confusion. These effects are often linked to neurological status changes that may occur as a serious complication, usually associated with severe electrolyte imbalance from high doses.


Q: Does Avolac interfere with routine blood tests?

A: Studies indicate that the active ingredient, lactulose, or its metabolites, can potentially interfere with certain laboratory tests. Specifically, it may interfere with measurements of serum creatinine when using a common testing method called the alkaline picrate (Jaffé) assay.


Q: What clinical trials led to the approval of Avolac?

A: The regulatory approval for the active ingredient, lactulose, is based on a body of clinical trials and studies. These trials demonstrated its effectiveness and safety profile for its approved uses, which typically involved measuring outcomes like changes in bowel movement frequency and specific blood nitrogen levels.


Q: Can Avolac be used by people who are vegetarians or vegans?

A: Lactulose, the active ingredient in Avolac, is a synthetic sugar that is chemically derived from lactose, which is milk sugar. Because of its origin from cow's milk, the final product is not generally classified as vegan.


Q: Does Avolac have any known long-term residual effects after stopping it?

A: Studies regarding the withdrawal of the active ingredient, particularly in patients treated for Hepatic Encephalopathy, suggest there may be a potential for the recurrence of symptoms. The long-term effects of stopping use should be managed under the guidance of a healthcare provider.

How should Avolac be stored and disposed of?

How to Store and Dispose of Avolac

Lactulose Solution (Avolac) must be maintained under specific conditions to preserve its stability and is subject to official disposal guidelines.

Storage Requirements

  • Temperature: Store at controlled room temperature, typically 20° to 25°C (68° to 77°F), and do not freeze.
  • Protection: Keep the solution protected from direct light and excess heat above 30°C. Prolonged exposure to high heat or light may cause extreme darkening and turbidity, rendering the product pharmaceutically objectionable.
  • Container: The medication must be kept in its original container and the cap must be secured tightly closed.
  • Child Safety: It must be stored out of the sight and reach of children and in a safe, up and away location.

Disposal

Unused or expired solution must be disposed of in accordance with local regulations. If no take-back program is available, it should be safely disposed of in the household trash, ensuring it is sealed and unappealing to children or pets.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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