Trimethoprim-Sulfamethoxazole

Trimethoprim-Sulfamethoxazole

Trimethoprim-sulfamethoxazole, a powerful antibiotic combination, can treat a wide range of bacterial infections. This versatile drug plays a crucial role in treating various conditions, from urinary tract infections to pneumonia. Doctors often prescribe it because of its effectiveness against many common bacteria.

This blog explores the benefits, dosage, and precautions of trimethoprim-sulfamethoxazole. We'll look at what this medication is, how to use it, and its potential side effects. 

What is Trimethoprim Sulfamethoxazole Tablet?

Trimethoprim-sulfamethoxazole, or co-trimoxazole, is an antimicrobial medication used to treat and prevent numerous bacterial infections. It is a fixed-dose combination of two active ingredients- trimethoprim and sulfamethoxazole, combined in a ratio of 1:5.

This combination creates a synergistic anti-folate effect, making it one of the most effective drugs against a wide range of bacteria.

Trimethoprim and Sulfamethoxazole Tablet Uses

Trimethon sulfamethoxazole is a versatile antimicrobial medication used to treat & prevent a wide range of bacterial infections. Its FDA-approved indications include:

• Acute infective exacerbation of chronic bronchitis
• Otitis media (ear infection) in paediatrics
• Traveller's diarrhoea for treatment and prevention
• Urinary tract infections
• Shigellosis (bacterial dysentery)
• Pneumocystis jirovecii pneumonia/Pneumocystis carinii pneumonia (PJP/PCP) for both prophylaxis and treatment
• Toxoplasmosis for both prophylaxis and treatment
• Trimethoprim/sulfamethoxazole is also helpful for:
• Prophylaxis in HIV-infected individuals
• Acne vulgaris
• Listeria infections
• Meliondosis
• Pertussis (whooping cough)
• Staphylococcus aureus infections, including methicillin-resistant Staphylococcus aureus (MRSA)
• Tuberculosis
• Whipple disease
• Isosporiasis
• Malaria
• Community-acquired pneumonia

How to Use Trimethoprim-sulfamethoxazole

Trimethoprim-sulfamethoxazole is available in oral and intravenous formulations. 

Trimethoprim-sulfamethoxazole tablets or liquid can be taken orally with or without food. However, taking them with at least one glass of water is best. Drinking optimal amount of fluids while taking this medication helps prevent kidney stone formation.

Dosage Information

Dosage for Bacterial Infections:

• For adults & children weighing 40 kg (88 pounds) or more, the recommended oral dosage is:
  • One 800 mg sulfamethoxazole/160 mg trimethoprim tablet every twelve hours for 10 to 14 days.
  • For children two months and older, the dosage is weight-adjusted, typically:
  • 40 mg/kg sulfamethoxazole & 8 mg/kg trimethoprim, divided into two doses every twelve hours for ten days.

Pneumocystis Pneumonia Treatment

For adults and children two months and older, the dosage is weight-adjusted:

• 75-100 mg/kg sulfamethoxazole and 15-20 mg/kg trimethoprim daily for 14-21 days.
• Traveller's Diarrhoea
• Adults: 800 mg sulfamethoxazole/160 mg trimethoprim every 12 hours for five days.

Chronic Bronchitis Exacerbations

For acute exacerbations due to certain bacteria:

• One 800 mg sulfamethoxazole/160 mg trimethoprim tablet every 12 hours for 10-14 days.

Urinary Tract Infections

• Pyelonephritis: One 800 mg sulfamethoxazole/160 mg trimethoprim tablet every 12 hours for 14 days.
• Prostatitis: One 800 mg sulfamethoxazole/160 mg trimethoprim tablet every 12 hours for 14 days or 2-3 months for chronic infections.

Trimethoprim/sulfamethoxazole is not recommended for children younger than two months old.

Side Effects of Trimethoprim-sulfamethoxazole Tablet

Trimethoprim-sulfamethoxazole is generally well-tolerated, but it can cause side effects.

Side effects that require immediate medical attention:

• Allergic reactions- Skin rash, itching, hives, swelling of the face, lips, tongue, or throat.
• Aplastic anaemia- Unusual weakness or fatigue, dizziness, headache, trouble breathing, increased bleeding or bruising, fever, chills, cough, or sore throat.
• Dry cough or shortness of breath
• High potassium level- Muscle weakness, fast or irregular heartbeat
• Liver injury- Right upper belly pain, loss of appetite, nausea, light-coloured stool, dark yellow or brown urine, yellowish-discolouration skin or eyes, unusual weakness or fatigue.
• Low blood sugar (hypoglycaemia)- Tremors or shaking, anxiety, sweating, cold or clammy skin, confusion, dizziness, rapid heartbeat
• Low sodium level- Muscle weakness, fatigue, dizziness, headache, confusion
• Fever, rash, and swollen lymph nodes
• Redness, peeling, or blistering of the skin, including inside the mouth
• Severe diarrhoea, fever.
• Small, pus-filled bumps on the skin
• Unusual vaginal discharge, itching, or odour
• Common side effects that may not require medical attention:
• Loss of appetite
• Nausea
• Vomiting
• Other common side effects include photosensitivity (increased sensitivity to sunlight), anorexia, dizziness, tinnitus, fatigue, insomnia, and rash/ urticaria.
• Sun Exposure: Trimethoprim-sulfamethoxazole may increase your sensitivity to sunlight. 
• If you have diabetes, trimethoprim-sulfamethoxazole may affect your blood sugar levels. 
• More serious but rare reactions can include Stevens-Johnson syndrome, various anaemias, agranulocytosis, Clostridium difficile-associated diarrhoea, myelosuppression, renal failure/interstitial nephritis, pancreatitis, and hepatotoxicity. Haemolytic anaemia can occur in patients with a glucose-6-phosphate-dehydrogenase (G6PD) deficiency.

Precautions

Following specific precautions while taking trimethoprim-sulfamethoxazole is crucial to ensure safe and effective treatment. Here are some essential precautions to keep in mind:

• Pregnancy and breastfeeding
• If you are allergic to sulfamethoxazole, trimethoprim, or other sulfa medications
• Inform your doctor about any severe allergies, asthma, or history of blood disorders caused by trimethoprim or sulfa drugs.
• Patients with AIDS 
• People with certain blood disorders (porphyria, folate deficiency anaemia), kidney disease, liver disease, vitamin deficiencies (folate or folic acid), decreased bone marrow function, G6PD deficiency, underactive thyroid, or mineral imbalances (high potassium or low sodium levels).
• Inform your doctor about taking trimethoprim-sulfamethoxazole before receiving any immunisations or vaccinations.
• Drug Interactions
• Medications that may interact with trimethoprim-sulfamethoxazole:
• Dofetilide 
• Leucovorin
• ACE inhibitors 
• Antiarrhythmics 
• Methotrexate
• Warfarin
• Phenytoin
• Digoxin
• Cyclosporine
• Medications that may require dose adjustments:
• Sulfonylureas (anti-diabetic drug) 
• Diuretics 
• Medications that may reduce the effectiveness of trimethoprim-sulfamethoxazole:
• Rifampin
• Methenamine

Conclusion

Trimethoprim-sulfamethoxazole stands out as a powerful tool in the fight against various bacterial infections. Its versatility in treating conditions ranging from urinary tract infections to pneumonia makes it a go-to choice for many doctors. The medication's unique mechanism of action, combining two active ingredients to disrupt bacterial folate synthesis, provides a strong defence against harmful microorganisms.

FAQ's

1. Is sulfamethoxazole a strong antibiotic?

While sulfamethoxazole alone is not considered a strong antibiotic, its synergistic effect with trimethoprim makes the combination a powerful antimicrobial agent. When combined with trimethoprim, sulfamethoxazole forms a potent antibiotic combination known as trimethoprim-sulfamethoxazole or co-trimoxazole. This combination is considered a broad-spectrum antibiotic, effective against various bacterial infections. 

2. Why take trimethoprim at night?

There are several reasons why trimethoprim is often recommended to be taken at night:

• Optimised effectiveness: Taking trimethoprim at bedtime allows the body's metabolic processes to work more effectively by aligning with the body's nighttime metabolic rates.
• Better absorption: Some evidence indicates that trimethoprim may be better absorbed by the body when taken at night.
• Reduced side effects: Certain trimethoprim side effects, such as nausea, may be less pronounced at bedtime.
• Convenience: Taking trimethoprim at night can be more convenient for some individuals, as it is easier to remember and fits into their daily routine.

3. How many days can you take sulfamethoxazole?

The duration of sulfamethoxazole (in combination with trimethoprim) treatment depends on the type of infection. Typically, it is prescribed for the following durations:

• Urinary tract infections (UTIs): 10-14 days
• Traveller's diarrhoea: 5 days
• Shigellosis (bacterial dysentery): 5 days
• Pneumocystis jiroveci pneumonia (PCP) treatment: 14-21 days

4. What are the disadvantages of trimethoprim-sulfamethoxazole?

While trimethoprim-sulfamethoxazole is an effective antibiotic combination, it does have some potential disadvantages:

• Allergic reactions
• Folate deficiency
• This medication can increase sensitivity to sunlight, increasing the risk of sunburn and skin reactions.
• Blood disorders, including aplastic anaemia, agranulocytosis, and thrombocytopenia (low platelet count).
• Kidney and liver toxicity
• Interactions with other medications, potentially altering their effectiveness or increasing the risk of side effects.

5. Who Cannot take trimethoprim?

Trimethoprim should be avoided or used with caution in certain individuals, including:

• Pregnant and breastfeeding mothers
• Infants younger than two months
• Individuals with severe liver or kidney disease:
• Individuals with folate deficiency or anaemia
• People with a history of severe allergic reactions to trimethoprim or sulfonamides
• Individuals take certain medications, such as dofetilide (an antiarrhythmic drug), leucovorin (used in cancer treatment), and methotrexate (used in cancer and autoimmune diseases).