Entrim

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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 Entrim

What is Entrim?

Entrim is a pharmaceutical medication developed for the management of specific chronic conditions. It belongs to a class of drugs designed to interact with biochemical pathways in the body to regulate physiological functions.

Mechanism of Action

The active components in Entrim work at a cellular level. By targeting specific receptors, the medication helps to stabilize biological processes that have become imbalanced due to underlying health conditions. This systemic approach is intended to address the root causes of symptoms rather than providing temporary relief.

Therapeutic Purpose

Entrim is primarily utilized in clinical settings to assist patients in achieving long-term stability. It is often integrated into broader treatment plans where consistent physiological monitoring is required. The medication is formulated to be released gradually, maintaining a steady concentration within the bloodstream to support ongoing health management.

Composition and Form

As a modern therapeutic agent, Entrim is the result of medicinal chemistry focused on bioavailability and stability. It is typically provided in standardized formats to ensure consistent delivery of the active ingredient. The formulation includes the primary compound along with excipients that ensure the integrity of the medication during storage and administration.

Regulatory References

  1. Co-trimoxazole: MedlinePlus Drug Information

What side effects are possible with Entrim?

Possible Side Effects and Safety Information

Entrim (Sulfamethoxazole and Trimethoprim) is associated with a risk of serious and potentially fatal adverse reactions, necessitating strict regulatory warnings.

Serious and Clinically Significant Risks

Severe and life-threatening reactions have been officially documented, most notably Severe Cutaneous Adverse Reactions (SCARs), including Stevens-Johnson syndrome (SJS), Toxic Epidermal Necrolysis (TEN), and Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS). These reactions can be preceded by flu-like symptoms, fever, or rash and require immediate discontinuation. Fatalities have also been reported due to hepatic necrosis, severe blood disorders (e.g., agranulocytosis, aplastic anemia), and acute pulmonary adverse reactions, including respiratory failure and circulatory shock.

Common Adverse Reactions

The most frequently reported side effects are generally confined to the gastrointestinal system (nausea, vomiting, loss of appetite, diarrhea) and dermatologic system (skin rash).

Safety Considerations and Restrictions

Contraindications restrict the use of Entrim in several populations, including pediatric patients under two months of age due to the risk of kernicterus, pregnant and nursing patients due to the potential for fetal harm and excretion into breast milk, and patients with marked hepatic damage or severe renal insufficiency that cannot be monitored. Patients with existing folate deficiency or certain blood disorders are also restricted from use. Caution is advised for the elderly and those with chronic conditions such as HIV/AIDS or G6PD deficiency. Monitoring for changes in renal function, hepatic function, and electrolyte levels (e.g., hyperkalemia, hyponatremia) is a high-level safety requirement as defined in labeling.

Overdose and Emergency Response

Overdose and When to Seek Help

Overexposure to Entrim (Co-trimoxazole) requires immediate emergency action as officially documented in regulatory information. Acute overdose may be manifested by a range of symptoms, including vomiting, fever, confusion, anorexia (loss of appetite), and dizziness. Physiological signs such as blood in the urine (hematuria) or crystal formation (crystalluria) are also documented.

Mandatory Emergency Action

You must seek immediate medical attention or call a Poison Help line if an overdose is suspected. The presence of severe neurological manifestations mandates contacting emergency services immediately. Regulators state that emergency services must be called if the individual has collapsed, had a seizure, has trouble breathing, or cannot be awakened.

Serious Outcomes and Management

Serious outcomes include the risk of seizure from acute overexposure and severe bone marrow depression from prolonged high-dose use. Management procedures officially described include general symptomatic and supportive treatment. For acute ingestion, gastric lavage or induced emesis may be indicated. In cases involving bone marrow depression, Folinic acid (Leucovorin) is documented as an effective specific intervention to address Trimethoprim’s anti-folate effects. Furthermore, forcing fluids is a required supportive measure to mitigate crystalluria risk. Population-specific warnings note that elderly patients and individuals with severe renal impairment are at greater risk for complications.

Therapeutic Uses of Entrim

Entrim: Main Uses and Therapeutic Benefits

Quick Facts: What Entrim Treats
Infectious Diseases
* Urinary tract infections
* Acute otitis media (pediatric use)
* Acute exacerbations of chronic bronchitis
* Travelers' diarrhea
* Shigellosis
Pneumocystis jirovecii* pneumonia (PJP/PCP), treatment and prevention
* Toxoplasmosis, treatment and prophylaxis

Entrim is an antimicrobial medication used to manage and prevent various bacterial infections caused by susceptible organisms. The therapeutic applications for this combination medication are extensive. A key use is the treatment of acute uncomplicated urinary tract infections. It is also frequently utilized in managing acute ear infections (otitis media) in the pediatric population and acute exacerbations of chronic bronchitis in adults.

Furthermore, Entrim has a role in managing specific gastrointestinal infections, including travelers' diarrhea and shigellosis. A particularly important application is the treatment and prevention of Pneumocystis jirovecii pneumonia (PJP), a severe infection that can affect individuals with weakened immune systems. The drug is also used for the treatment and prophylaxis of toxoplasmosis.

Regulatory References

  1. NIH MedlinePlus guidance on Sulfamethoxazole and Trimethoprim

Eligibility and Restrictions for Use

Entrim (Co-trimoxazole) is subject to strict eligibility rules documented in official regulatory labeling to define who can and cannot use the medicine.

Contraindicated Populations

Absolute contraindications apply to patients with a known hypersensitivity to sulfonamides or trimethoprim, infants less than two months of age, pregnant patients at term, and nursing mothers. The medicine is also prohibited for use in patients with marked hepatic damage, severe, unmonitorable renal insufficiency (Creatinine Clearance <15 mL/min), or documented megaloblastic anemia due to folate deficiency.

Conditional and Restricted Use

Entrim is approved for use in children two months of age and older. Patients with moderate renal impairment ( CrCl 15 to 30 mL/min) are eligible for conditional use that requires a mandatory dosage modification as defined by the labeling. The elderly and patients with specific metabolic disorders, such as G-6-PD deficiency, are classified as restricted-use populations, requiring caution and close monitoring.

What should I know about interactions with other medicines?

Entrim Interactions with other medicines and products

Entrim (Co-trimoxazole) has several formally documented interaction patterns based on regulatory labeling, primarily due to the inhibition of metabolic enzymes and competition for renal clearance pathways. These interactions often lead to an officially stated increase in the plasma concentration and exposure of co-administered medicines.

Official Interaction Restrictions and Risks

Category Documented Interaction Outcome
Formal Contraindication Co-administration with Dofetilide is prohibited due to the severe, officially documented risk of elevated Dofetilide plasma levels, which can lead to QTc prolongation.
Anticoagulants Combined use with Warfarin may potentiate the anticoagulant effect, requiring close monitoring due to decreased Warfarin clearance.
Anticonvulsants Co-administration with Phenytoin results in decreased hepatic clearance, leading to officially documented increases in Phenytoin plasma concentrations.
Folate Antagonists The combination with Methotrexate increases the risk of myelosuppression (blood cell suppression) due to an additive pharmacodynamic anti-folate effect.
Hyperkalemia Risk Combined use with agents that increase potassium (e.g., ACE Inhibitors, ARBs) carries an additive risk of hyperkalemia (high potassium levels).
Specific Populations Increased Digoxin blood levels are officially noted as being more pronounced in elderly patients.

The official labeling also documents an interaction with Ethanol (Alcohol), which carries the risk of a Disulfiram-like reaction.

Mechanism of Action

Entrim, known chemically as Co-trimoxazole, employs a strategic sequential dual-blockade targeting two critical enzymes in the microbial metabolic pathway necessary for growth and replication to achieve a consequence at the microbial level.

Dual Inhibition of Folic Acid Synthesis

The mechanism operates within the domain of anti-metabolite enzyme inhibition, striking the microbial folic acid synthesis pathway at two successive points. Sulphamethoxazole acts as a competitive inhibitor of Dihydropteroate Synthase, and immediately after, Trimethoprim inhibits Dihydrofolate Reductase (DHFR). This sequential action prevents the formation of Tetrahydrofolate, a crucial cofactor required for cellular components.

Synergy and Bactericidal Action

A crucial physiological event involves the pharmacodynamic synergy between the two components. By simultaneously disrupting two steps, the overall inhibition is amplified beyond the simple sum of the individual parts, which characterizes the shift from bacteriostatic (growth inhibition) to a bactericidal (killing) action. This interference with metabolism halts DNA and RNA biosynthesis, resulting in the destruction of susceptible microbial populations.

Dosage and Administration Information

How to Use Entrim

Entrim, known internationally as Co-trimoxazole, is administered through two officially approved routes: oral (using tablets or suspension) and intravenous (IV) infusion. The choice of route depends on the specific infection being addressed and the patient's condition, with the IV route typically reserved for severe cases or when oral administration is not possible.


Standard Dosing and Frequency Patterns

The standard adult dosing for many acute systemic infections, such as uncomplicated urinary tract infections or acute bronchitis, involves taking one Double Strength (DS) tablet (800 mg SMX/160 mg TMP) every 12 hours. However, for severe infections, such as the treatment of Pneumocystis jirovecii pneumonia (PJP), the total daily dose is based on the Trimethoprim component and is divided and administered more frequently, typically every 6 to 8 hours. Prophylaxis against PJP may use a less frequent schedule, such as once daily or three times per week.


Administration Conditions and Adjustments

Oral doses may be taken with a full glass of water, and taking the medicine with food or drink can help minimize gastrointestinal discomfort. For the IV solution, the concentrate must be diluted immediately prior to use and administered as an infusion over 60 to 90 minutes; rapid injection is prohibited. Dosing adjustments are strictly mandated for patients with compromised kidney function. For moderate renal impairment (Creatinine Clearance 15 to 30 mL/min), the official regimen requires half the standard dose. The medicine is generally not used in infants under two months of age. The duration of therapy is fixed, ranging from 5 days for short-course treatments to 21 days for severe infections like PJP.

Recent Clinical Evidence

Research Evidence: Overview of Studies for Entrim

Evidence for Use in Urinary Tract Infections (UTI)

The evidence for using Entrim for managing acute uncomplicated urinary tract infections is derived from Randomized Controlled Trials (RCTs) and Systematic Reviews. The studies primarily examined outcomes related to physical discomfort, such as outcomes related to inflammatory or irritative states (e.g., pain and frequency), and monitored bacteriological eradication, which is used in research exploring how symptoms change over time. The study populations were mainly non-pregnant women with acute infection, though some research was observed in older adults. The findings from these historical studies describe patterns related to the measurement of symptom resolution and outcomes related to systemic or functional imbalance over defined, short treatment periods.

Evidence for Use in Treating and Preventing Pneumocystis Pneumonia (PJP)

This infection was studied for both its acute management and its long-term prevention in immunocompromised individuals. The older, foundational studies in this area reported data show patterns related to outcomes reflecting daily functioning or activity level in groups receiving Entrim when compared to those receiving other specific interventions. A significant limitation is that the majority of definitive RCTs predate modern immunosuppression protocols, meaning results apply only to the populations studied at that time.

Research on Prophylaxis and Prevention of PJP

Long-term RCTs and Observational Studies explored the use of Entrim for primary and secondary prevention. The research examined outcomes related to physical discomfort in individuals receiving prophylaxis compared to those receiving placebo or no intervention. The research base for PJP prevention is detailed, but data for certain groups remain insufficient.

Evidence Gaps and Research Uncertainties

Key uncertainties remain across the evidence base. The high global prevalence of antimicrobial resistance was observed in some studies, and research highlights that the applicability of older, foundational clinical trials remains uncertain for infections like UTIs and Shigellosis. Additionally, follow-up durations were limited in many acute treatment trials, meaning there is limited information for long-term outcomes beyond prophylaxis.

Key Studies & References

  1. Sulfamethoxazole and Trimethoprim: Drug Information, Indications, and Use
  2. Meta-analysis of randomized trials of trimethoprim-sulfamethoxazole versus alternative regimens for the treatment of mild-to-moderate Pneumocystis carinii pneumonia
  3. Systematic review and meta-analysis of co-trimoxazole versus amoxicillin for acute otitis media in children

Frequently Asked Questions (FAQ)

Common questions about Entrim (FAQ)


Q: Is Entrim used for conditions other than the main one listed?

Official regulatory documents describe Entrim as indicated for a variety of systemic bacterial infections beyond the most common ones. According to the official product information, this typically includes acute otitis media, Shigellosis, traveler's diarrhea, and specific lung infections like Pneumocystis jirovecii pneumonia (PJP). The full scope of approved uses can be found in the official labeling.


Q: Is Entrim considered a safe option for older adults?

Official labeling indicates that Entrim may be used in older adults, but caution is advised. This is because age-related changes, such as reduced kidney or liver function, can affect how the medicine is processed by the body. Closer monitoring is often necessary, and official guidelines describe dosage adjustments that are required if kidney function is compromised.


Q: Does taking Entrim with food change how it is absorbed?

Official administration instructions advise taking Entrim with food or drink primarily to help minimize potential gastrointestinal discomfort, such as nausea or an upset stomach. Regulatory information focuses on minimizing patient discomfort through this administration condition.


Q: Why is Entrim sometimes preferred over other drugs for the same condition?

Entrim is described in official documents as having a unique dual-action mechanism that results in a powerful, synergistic effect against susceptible bacteria. Regulatory information supports its use in cases where this specific mechanism is deemed advantageous over other antimicrobial options. This advantage is often related to its ability to achieve a reliable bactericidal action (meaning it kills the target bacteria).


Q: What is the shelf life of Entrim once the package is opened?

For the oral tablets and suspension, the official documents state they should be stored at controlled room temperature and protected from light and moisture. For the intravenous (IV) solution, once it has been diluted for use, it must be used within a very limited time frame, typically between 2 and 6 hours depending on the concentration. Regulatory documents describe that any unused contents in a multiple-dose IV vial should be used within 48 hours.


Q: How quickly should someone expect Entrim to start working?

Studies and official information indicate that the active components reach their peak levels in the blood approximately 1 to 4 hours after taking an oral dose. Based on official patient information, individuals typically begin to notice improvement in their symptoms during the first few days of treatment.


Q: Is it normal to feel [vague symptom, e.g., slightly tired] when first starting Entrim?

Official adverse reaction reports list general effects such as dizziness, headache, and a feeling of weakness or unusual tiredness among the possible outcomes. If these or any other concerning effects are experienced, official guidelines describe that the medicine should be discontinued immediately, and consultation with a healthcare provider is necessary.


Q: Are there specific food items or drinks that need to be avoided when using Entrim?

The official product labeling documents a specific interaction with ethanol (alcohol) that carries the risk of a Disulfiram-like reaction. Furthermore, caution is advised when taking Entrim alongside other agents or foods high in potassium, as the combination may lead to an increased risk of high potassium levels, known as hyperkalemia.


Q: What is the typical timeframe before knowing if Entrim is right for me?

The duration of treatment with Entrim is fixed by the official regimen, often lasting between 5 and 21 days depending on the infection. Official patient information notes that improvement in symptoms is generally expected within the first few days of starting the medicine.


Q: Are there any specific safety warnings associated with long-term use of Entrim?

When used for extended periods, regulatory documents warn of a specific risk of developing folate deficiency, which can lead to blood disorders. Additionally, as with any antibiotic, official labeling notes that prolonged use carries a general risk of a secondary infection caused by organisms that are not susceptible to Entrim (superinfection).


Q: Is Entrim known to cause weight gain or weight loss?

Official documentation of adverse reactions notes that weight loss has been observed as a possible outcome. The frequency of this effect is not defined in the official regulatory data.


Q: Can Entrim affect sleep patterns?

Official product documentation lists insomnia, or trouble sleeping, as a possible adverse reaction. Patients experiencing this effect may be advised to consult with their healthcare provider, according to general safety principles.


Q: Why do some people stop taking Entrim?

Official regulatory instructions state that the medicine is required to be stopped immediately if a patient shows any signs of a serious adverse reaction, such as a severe rash, fever, or jaundice (yellowing of the skin or eyes). These mandatory discontinuations are the primary reasons for stopping the drug as outlined in the official safety information.


Q: What should I do if I experience a potential interaction while on Entrim?

Official patient information advises immediate discontinuation of the medicine upon observation of a serious reaction. The product labeling states that contact with a healthcare provider should occur as soon as possible to report the clinical signs.


Q: What are the rules regarding driving or operating machinery while taking Entrim?

Official documents list dizziness and other effects on the nervous system as possible adverse reactions. Because of this, patient information indicates that individuals should exercise caution when driving or operating machinery until they understand how the medicine affects their alertness and coordination.


Q: How long does Entrim stay in your system after stopping treatment?

Regulatory data on pharmacokinetics indicates the medicine's clearance is measured by its half-life, which is approximately 10 hours for one component and 8 to 10 hours for the other. As a result, detectable amounts of the medicine's active components are generally present in the bloodstream for up to 24 hours after the last dose.


Q: Is Entrim ever prescribed in combination with other medications for the same condition?

While Entrim is often used as a single agent, the official regulatory monograph notes that for certain serious or complicated infections, such as those caused by Brucella, it is sometimes used in combination with other anti-infective medicines. This combination approach is defined by clinical guidelines.


Q: Can Entrim be taken with vitamins and herbal supplements?

Official labeling includes warnings regarding the use of Entrim alongside folate antagonists (medicines that reduce folic acid), as this combination increases the risk of blood cell suppression. Additionally, the drug is contraindicated in patients with an existing folate deficiency. This information is relevant to supplements that contain folic acid or B-vitamins.

How should Entrim be stored and disposed of?

How to Store and Dispose of Entrim (Sulphamethoxazole and Trimethoprim)

Official regulatory labeling dictates strict storage and disposal requirements to maintain Entrim's stability.

Required Storage Conditions

Tablets and Suspension must be stored at controlled room temperature, 20 C to 25 C. The oral forms must be protected from light and moisture and kept in a tight, light-resistant container. The Intravenous Solution (undiluted or diluted) must not be refrigerated.

Stability and Handling

Once the Intravenous Solution is diluted, it has a limited stability period and must be used within a few hours (e.g., within two to six hours depending on concentration). All forms must be stored out of the sight and reach of children.

Disposal

Unused or expired Entrim must be thrown away following official governmental or local regulatory guidelines for safe disposal.

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

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