Paser

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Paser

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Treatment option: Tuberculosis

Medically reviewed

Marina Burgos

Last updated on 10/01/2026

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 Paser

What is Paser? — Foundational Overview

Property Description
Active ingredient Aminosalicylic Acid (p-Aminosalicylic acid, 4-ASA)
Form Coated Granules or Powder
Pharmacological class Antitubercular Agent (Antimycobacterial)
Common use Management of drug-resistant tuberculosis
Origin Synthetic

What Type of Medicine is Paser (Aminosalicylic Acid)?

Paser is a synthetic, single-ingredient medicine whose active substance is Aminosalicylic Acid, also known by the chemical designations p-Aminosalicylic acid or 4-ASA. It is precisely classified as an antitubercular agent (antimycobacterial), a pharmacological class recognized for its role in long-term infection control. The drug is regarded as an essential medicine, underscoring its value in managing serious global infectious diseases. Paser serves a function as a second-line agent in complex treatment regimens. This designation ensures the drug is primarily reserved for individuals facing infection challenges where conventional first-line therapies are no longer effective against resistant strains.

Composition and Form: The Oral Granule Preparation

The pharmaceutical preparation of Paser consists of the active ingredient Aminosalicylic Acid. It is most commonly supplied in the form of specialized coated granules intended for oral administration, although powder and tablet forms may also exist. The oral route is practical for the extended durations required for antitubercular treatment. The use of specialized coated granules, a key feature of this formulation, represents an engineered dosage form designed to optimize the release and systemic absorption of the medicine, which is necessary for maintaining consistent therapeutic levels during long-term therapy.

General Purpose: Controlling Drug-Resistant Infections

The general purpose of Aminosalicylic Acid is to suppress the growth of infectious bacteria, specifically strains of Mycobacterium tuberculosis. Its primary benefit is to manage and stabilize complex, drug-resistant infections, which often fail to respond to standard medications. The medicine is utilized for managing cases of multi-drug-resistant tuberculosis. By being deployed as a component in comprehensive multi-drug protocols, Paser helps restrict the propagation of resilient pathogens, offering a therapeutic option for controlling the disease in patients who have exhausted primary treatment options.

Regulatory References

  1. WHO Essential Medicines List Entry for 4-Aminosalicylic acid

What side effects are possible with Paser?

The official safety profile for Paser (Aminosalicylic Acid) documents possible adverse reactions based on frequency and the body system affected, strictly following regulatory standards.

Adverse effects related to the gastrointestinal system are commonly documented in official labels, including nausea, vomiting, diarrhea, abdominal pain, bloating, and gastrointestinal intolerance. Hypothyroidism and general cutaneous hypersensitivity, such as skin rash, are also classified as common adverse reactions.

The regulatory label places specific emphasis on rare but clinically significant adverse reactions. These serious effects include severe hepatic toxicity (such as drug-induced hepatitis and jaundice), serious hematologic disturbances (including agranulocytosis and hemolytic anemia), and systemic reactions (such as pericarditis and lymphoma-like syndrome).

Safety statements note that the onset of drug-induced hepatitis typically occurs within the first three months of initiating therapy. Due to the risk of severe systemic reactions, the label mandates that treatment must be discontinued immediately at the first sign of fever, rash, or other premonitory signs of intolerance. Paser is formally contraindicated in individuals with known hypersensitivity to the active substance and in those with severe renal disease. Caution is also required in patients with pre-existing severe hepatic disease, and official documents advise against breastfeeding during use.

Overdose and Emergency Response

Overdose and Immediate Medical Attention

If an overdose of Paser (aminosalicylic acid) is suspected, immediate medical care or contact with a poison control center is required. Paser is a salicylate, and acute or chronic toxicity from salicylates can be serious, affecting multiple organ systems.

While specific Paser overdose symptoms are not always detailed in standard regulatory documents, the clinical profile of salicylate poisoning can include nausea, vomiting, dizziness, tinnitus (ringing in the ears), confusion, and severe changes in the body’s acid-base balance (metabolic acidosis).

Urgent medical attention is also required if you experience signs of severe adverse effects, which may be related to toxicity or an excessive dose. These signs include:

  • Signs of serious allergic reaction (rash, hives, swelling, or difficulty breathing).
  • Signs of liver problems (jaundice, dark urine, severe fatigue, or persistent abdominal pain).
  • Unexplained bleeding or bruising, fever, chills, or persistent severe vomiting.

Population-Specific Overdose Risk

A critical, population-specific warning for Paser is the risk of Reye's syndrome. This severe condition causes acute problems to the brain and liver. To avoid this risk, Paser must not be given to children and teenagers who have or are recovering from viral illnesses, such as flu signs or chickenpox. Always discuss the risk profile with a healthcare professional, especially when managing care for children or for any signs of toxicity.

Therapeutic Uses of Paser

What Paser Treats: Main Uses and Benefits

Paser is generally used for managing tuberculosis infections that have become resilient, specifically in cases considered drug-resistant (DR-TB). Its role is to suppress the growth of these complex pathogens, providing necessary support when conventional first-line treatments have failed. The medication is considered relevant for use as part of combination regimens when supportive treatment is required due to resistance or tolerability. The medication is relevant in conditions characterized by periods of heightened symptoms, such as multi-drug resistant tuberculosis (MDR-TB) and other forms of drug-resistant disease.

The therapeutic benefit generally extends to addressing symptom clusters that create noticeable physiological strain. By addressing the underlying cause, Paser assists with maintaining functional stability and contributes to easing the overall symptom load, managing symptoms such as persistent fever, night sweats, and unintentional weight loss that may interfere with daily functioning. The medication plays a role in managing multi-drug protocols for patients facing challenging forms of the disease.

“The medication is considered relevant for use when supportive symptom management is appropriate for patients facing drug resistance.”

The use of Paser contributes to improved comfort during periods of heightened symptoms and helps maintain the necessary therapeutic coverage to prevent the infection from progressing further, thereby supporting general well-being during symptomatic phases. The drug is utilized within clinical settings that involve heightened systemic burden.


Quick Fact: Supports Managing Constitutional Symptoms

Paser is applicable within clinical settings that involve heightened systemic burden, and is commonly used to help with symptoms related to systemic imbalance, such as persistent fever and unintended weight loss linked to active infection.

Eligibility and Restrictions for Use

Official Eligibility and Contraindications for Paser

Paser (Aminosalicylic Acid) is officially used in combination regimens for multi-drug resistant tuberculosis (MDR-TB) in adults and children from 28 days of age and older. However, regulatory documents establish strict rules governing patient eligibility and non-eligibility.

Classification Population or Condition
Absolute Contraindication Known hypersensitivity to aminosalicylic acid or its ingredients.
Absolute Contraindication Patients with severe renal disease (end-stage renal disease).
Absolute Contraindication Patients with severe hepatic disease or gastric/duodenal ulcers (for some formulations).
Restricted Use/Caution Moderate renal impairment or hepatic impairment.
Restricted Use/Caution Patients with G6PD deficiency or HIV co-infection (monitor thyroid function).
Not Recommended Pregnancy and lactation (breastfeeding).
Age Restriction Children/teenagers with or recovering from viral infections (risk of Reye's syndrome).

These regulatory classifications define who can receive the medicine: it is established for adults and children for specific resistant infections but is contraindicated by regulatory authorities for individuals with severe organ dysfunction. Use in pregnancy and breastfeeding is officially not recommended.

What should I know about interactions with other medicines?

Interactions with other medicines and products

Pharmacokinetic and Pharmacodynamic Interactions

The regulatory documentation for Paser (Aminosalicylic Acid) identifies several specific interaction patterns. The co-administration of Dichlorphenamide is formally classified as contraindicated due to the potential for increased Aminosalicylic Acid plasma levels and associated toxicity.

Paser can interfere with the absorption of other medicines from the gastrointestinal tract, notably causing reduced systemic exposure of Rifamycins (e.g., Rifampin) and Digoxin. To manage this effect, official labeling specifies that Paser must be administered 8–12 hours apart from Rifampin.

Pharmacodynamic interactions involve an additive risk of toxicity with other antitubercular agents. Co-administration with Ethionamide or Prothionamide is associated with an increased risk of Hypothyroidism. Use with Isoniazid may increase the risk of Hepatotoxicity.

Food, Supplements, and Administration Restrictions

Aminosalicylic Acid can interfere with the absorption of oral Cyanocobalamin (Vitamin B12), potentially leading to reduced serum levels. The ingestion of alcohol is linked to an increased risk of gastrointestinal toxicity and bleeding. For the coated granule formulation, the medicine must be administered with acidic food or drink (pH < 5) and is prohibited from being mixed with neutral pH substances like milk, which is a required condition for proper drug release.

Clearance and Accumulation Risks

Official labeling notes that the accumulation of the drug's metabolite in patients with severe renal disease may worsen existing acidosis. Caution is also advised in patients with severe hepatic impairment due to the documented risk of drug accumulation.

Mechanism of Action

Inhibition of Bacterial Growth and Replication

This domain centers on Paser's action as a competitive inhibitor of the bacterial enzyme dihydropteroate synthase. By structurally mimicking para-aminobenzoic acid (PABA), Paser blocks the active site, preventing the synthesis of folic acid. Since folate is an essential precursor for DNA and RNA production, this inhibition results in impaired cellular division and halted bacterial replication.


Impairment of Bacterial Metabolic Integrity

Paser’s mechanism includes a secondary, multi-faceted action: it acts as a chelator, binding to and limiting the availability of iron within the bacterial cell. Iron is critical for bacterial energy production and metabolic integrity. This iron deprivation impairs the organism's structural and metabolic functions, which contributes to the physiological consequence of decreased bacterial functionality.


Modulation of Macrophage Phagocytic Activity

The drug also functions as a modulator of the host's innate immune response. This action enhances the function of immune cells, specifically macrophages, supporting their capacity to engulf and process bacteria. This physiological enhancement of the immune system contributes to the overall reduction of viable bacteria.

Dosage and Administration Information

Administration Route and Dosing Regimen

The administration of Paser (aminosalicylic acid) is strictly for oral use and is supplied as 4 gram gastro-resistant coated granules. The standardized adult dosing regimen is 4 grams taken three times per day, resulting in a maximum total daily dose of 12 grams. This consistent dosage is typically scheduled at approximately 8-hour intervals. As a component of long-term protocols for drug-resistant tuberculosis, the medicine is used in combination with other antitubercular agents for a duration that typically extends for 24 months.

Preparation and Consumption Rules

To maintain the drug's specialized gastro-resistant coating and ensure proper release outside of the stomach, the granules must be taken with food and administered with specific preparation. The full dose of granules should be mixed with soft, acidic food (such as applesauce or yogurt) or suspended in an acidic liquid (such as orange or tomato juice). The granules must be swallowed immediately after preparation and must not be crushed or chewed at any point.

Population-Specific Adjustments

For infants, children, and adolescents, the total daily dosage is weight-dependent, typically 150 mg/kg per day, which is administered in two divided intakes. High-level dosage adjustment is required for patient populations with renal impairment. If a dose is missed, standard procedures involve taking the dose as soon as remembered, unless the next scheduled dose is nearly due, in which case the missed dose is skipped.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Paser

Evidence for Use in Drug-Resistant Tuberculosis (DR-TB)

Paser was studied in research contexts that explored complex multi-drug regimens for individuals facing drug-resistant forms of tuberculosis, including Multi-Drug Resistant Tuberculosis (MDR-TB) and Extensively Drug-Resistant Tuberculosis (XDR-TB). The research examined includes large-scale systematic reviews and meta-analyses, which aggregate findings from numerous global patient cohorts. Studies monitored outcomes reflecting daily functioning and activity level, which are relevant in conditions where symptoms may vary in intensity.

The main focus of these reviews was on fundamental endpoints related to the course of the disease. Research examined bacteriological endpoints, such as sputum culture conversion, and composite outcomes labeled as treatment success. Findings describe patterns observed in the studies that monitored populations receiving these complex multi-drug regimens over the course of therapy. However, the evidence level for Paser’s role in modern regimens is broadly categorized as moderate, primarily because dedicated contemporary, large-scale randomized controlled trials (RCTs) are scarce.

Evidence for Role in Preventing Companion Drug Resistance

Paser was evaluated in studies that explored its use in combination therapy, specifically examining patterns related to acquired resistance in other antitubercular agents. This research foundation includes historical Randomized Controlled Trials (RCTs) and modern Pharmacokinetic/Pharmacodynamic (PK/PD) studies. Research describes patterns indicating that, in historical contexts, the inclusion of Paser was studied for its association with patterns of resistance development in certain drugs.

What Is Still Uncertain About Paser

The evidence exhibits heterogeneity across studies, with reliance on aggregated cohort data rather than uniform contemporary RCTs for the current primary indication. Follow-up durations, while long for the immediate treatment phase (12 to 24 months), are limited when considering outcomes over many years post-therapy. Data for certain groups, such as pediatric patients and those with HIV co-infection, remain insufficient for comprehensive guidance.

Frequently Asked Questions (FAQ)

Common questions about Paser (FAQ)

Q: How quickly does Paser start working after you take it?

A: Paser is an antitubercular agent used as part of a comprehensive, long-term treatment plan. The active substance is absorbed rapidly and reaches its peak concentration in the bloodstream within a few hours. However, the drug functions over a prolonged duration, which is consistent with the management of chronic infection.


Q: Can Paser be taken with food, or should it be on an empty stomach?

A: Regulatory documents require Paser granules to be taken with food or an acidic liquid (such as orange juice) to protect the specialized gastro-resistant coating and ensure proper drug release. Mixing with neutral substances like milk is prohibited by official administration rules.


Q: What happens if you miss a dose of Paser?

A: If a dose is missed, procedural guidelines state the dose should be taken as soon as it is remembered. However, if the time for the next scheduled dose is nearly due, the missed dose is typically skipped. Taking two doses close together is not advised by these guidelines.


Q: What is the duration of treatment typically described for Paser?

A: The medicine is used as a component of long-term protocols for drug-resistant tuberculosis. Regulatory documents indicate that the duration of treatment typically extends for a period of 12 to 24 months in combination with other antitubercular medicines.


Q: What if I take Paser and don't feel any different—is that normal?

A: As a second-line antitubercular agent, the medicine is intended to suppress bacterial growth over an extended period. Because it is not for acute symptom relief, the absence of an immediate subjective feeling of change is generally consistent with its intended role in managing chronic infection.


Q: Can teenagers or children use Paser?

A: Paser is formally indicated for use in adults and children from 28 days of age and older for specific resistant infections. However, official regulatory caution is noted for use in children and teenagers who are recovering from viral infections, as this may be linked to a theoretical risk of Reye's syndrome.


Q: Can Paser cause problems with the liver or kidneys?

A: Official warnings note the medicine is formally contraindicated, meaning prohibited, in patients with severe renal disease and severe hepatic disease. Regulatory labels document the risk of severe hepatic toxicity, such as drug-induced hepatitis, and the accumulation risk in severe kidney impairment.


Q: Does Paser interact with common pain relievers like ibuprofen?

A: Official interaction profiles indicate a potential for additive effects when Paser is used with some common pain relievers, such as ibuprofen and aspirin. This potential interaction may be related to Paser's similarity to salicylates and a shared risk of gastrointestinal irritation.


Q: Is it true that Paser has specific dietary restrictions?

A: The official labeling does not impose broad dietary restrictions, but it requires that the granules be mixed with an acidic food or acidic liquid for proper administration. Official administration rules do not permit mixing the drug with neutral substances like milk to ensure the drug's specialized coating dissolves correctly.


Q: What does 'contraindication' mean when discussing Paser?

A: A contraindication is a regulatory term for a condition or factor that makes the use of Paser medically inadvisable due to the potential for significant patient harm. Examples of contraindications for Paser are known hypersensitivity to the drug or the presence of severe renal disease.


Q: Is Paser a controlled substance?

A: The active ingredient, aminosalicylic acid, is an antitubercular agent and is not classified as a federally controlled substance in the United States. Regulatory and pharmacological profiles do not list it as a substance with a high potential for abuse.


Q: Is Paser addictive or habit-forming?

A: Paser is an antitubercular medicine used to treat bacterial infection. Official regulatory and pharmacological profiles do not indicate that the medicine is addictive or habit-forming.


Q: Is it normal to feel tired after starting Paser?

A: Official regulatory labels for Paser list fatigue and unusual tiredness or weakness as possible adverse reactions. These effects can be related to either general side effects or they can be associated with more serious systemic reactions, which should be monitored.


Q: What is the half-life of Paser?

A: The elimination half-life is a measure of how quickly the drug is cleared from the bloodstream. For Paser's active substance, the reported average elimination half-life in healthy volunteers is short, typically between 26 and 40 minutes.


Q: How long does Paser stay in the body after the last dose?

A: The drug is processed relatively quickly, given its short elimination half-life (less than an hour). However, pharmacokinetic studies show that measurable concentrations of the active substance in the blood are generally maintained for approximately 8 to 9 hours after a single dose.


Q: Is Paser used for any other conditions besides the main one listed?

A: The official, regulatory indication for Paser is strictly the treatment of tuberculosis in combination with other anti-tuberculosis agents. The drug is not formally labeled or indicated for use in any other condition.


Q: Is Paser gluten-free or lactose-free?

A: While the official inactive ingredient list does not typically include gluten or lactose, regulatory documentation does not provide a formal 'gluten-free' or 'lactose-free' designation for the final commercial product.


Q: Is Paser a widely used medicine globally?

A: Paser (aminosalicylic acid) is listed on the World Health Organization's (WHO) Model List of Essential Medicines. This classification confirms its indispensable status in global public health for managing serious infectious diseases, particularly drug-resistant tuberculosis.

How should Paser be stored and disposed of?

Storage Requirements for Paser Granules

Paser (para-aminosalicylate sodium) must be stored under specific environmental conditions to maintain its integrity. Regulatory documents require the product to be kept at a temperature below 15 C (59 F), generally requiring storage in a refrigerator or freezer. The medication must be protected from excessive heat, light, and moisture, and must remain in its original packet or container.

Stability and Child Safety

The product must not be used if the granules change color to dark brown or purple or if the packet appears swollen, as these indicate degradation. As a mandatory safety constraint, the medicine must be stored out of the reach of children.

Disposal of Unused Product

Unused or expired Paser should be disposed of in accordance with local requirements. The preferred method for disposal is through an official drug take-back program. If this is unavailable, the medicine can be mixed with an undesirable substance, placed in a sealed container, and discarded in household trash.

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

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