Bactrim is a combination antibiotic of two drugs, Sulfamethoxazole and Trimethoprim. It is used to treat a variety of bacterial infections such as pneumonia, bronchitis, infections of the urinary tract, and ear infections. It is indicated for use by adults and children above two months.
The Trimethoprim and Sulfamethoxazole combination is also known as Co-trimoxazole. This cost-affordable drug is available as tablets, oral suspension, and injection solutions. In order to avoid developing drug-resistant bacteria and maintain its effectiveness, Bactrim should be used only to treat infections that are suspected to be caused by susceptible bacteria. It works by stopping the growth of bacteria causing infections.
Bactrim is formed by combining two antibiotics: Sulfamethoxazole and Trimethoprim. The drug belongs to the class of antibiotics that treat mild to moderate bacterial infections and for the prevention of opportunistic infections in immune-deficient individuals. It is available in multiple generic and trade formulations like Cotrim, Septra, and Sulfatrim.
What Is Bactrim Used For?
- Some of the FDA-approved indications for Bactrim are to treat respiratory infections like acute infective exacerbation of chronic bronchitis.
- It is the most frequently prescribed for treatment and prophylaxis of traveler’s diarrhea, and urinary tract infections.
- Bactrim is used to treat bloody diarrhea, in patients with Shigellosis, a bacterial intestinal infection in adults, and patients two months of age and older.
- It is indicated in the treatment of Pneumocystis jirovecii pneumonia in adults and pediatric patients.
Bactrim helps to relieve pain and drainage in a middle ear infection Otitis media. However, due to the possibility of severe side effects, this drug should not be given to children under the age of two months.
How Does Bactrim Work?
In general, Sulfamethoxazole stops bacteria from making dihydrofolic acid and trimethoprim prevents the formation of tetrahydrofolic acid. The combination of trimethoprim and sulfamethoxazole in Bactrim creates a synergistic anti- folate effect and halts the production of tetrahydrofolate to its active form of folate. Bactrim antibiotic is bactericidal and blocks the two steps of the biosynthesis of essential nucleic acids and proteins inside the bacteria.
What Is Its Onset of Action?
Bactrim may be administered orally with or without food. The drug is administered as a tablet formulation of a 1:5 ratio of Trimethoprim and Sulfamethoxazole. This ensures their peak concentration of 1 to 20 throughout the blood tissues for the desired effect. The peak blood levels for each individual component occur one to four hours after it is taken orally. Sulfamethoxazole and Trimethoprim have a mean serum half-life of 8 to 10 hours. The excretion of Bactrim is primarily by the kidney and has a higher concentration in urine than in blood.
No habit-forming tendencies have been reported in people after taking Bactrim.
The medicine should not be taken after it expires. The expiry date will be printed on the medicine pack.
What Is the Dosage of Bactrim?
Use of the drug in children younger than two months of age is not recommended.
How to Use Bactrim?
Bactrim may be administered orally with food, water, or milk to avoid gastritis. It is available in oral and liquid form and in injectables. The medicine must be taken as instructed by the doctor. For patients taking the oral liquid, use a specially marked measuring spoon to measure each dose accurately. A minimum of six hours gap should be between each dose. Do not change the dose unless directed by the doctor.
In case you miss a dose, the medicine should be taken as soon as you remember. Do not take two tablets together as it may cause adverse effects. Do not take a double dose and take the next dose.
What Are the Drug Warnings and Precautions?
If you have any of the following, inform your doctor before taking Bactrim:
- Pregnancy and Breastfeeding Women - It may lead to congenital malformation for the developing baby. Bactrim may pass into the breast milk and cause undesirable side effects to the infant.
- Severe Allergy - Bactrim is not indicated in people with known hypersensitivity to either drug or a past sulfa allergy.It should be administered with caution in patients with bronchial asthma, severe allergies, and AIDS.
- Kidney Disease - Bactrim is not recommended in people with severe kidney disease and may increase the risk of side effects in the elderly if not monitored.
- Liver Failure - The drug-induced liver injury and jaundice should be used with caution.
- Anemia - Bactrim should be given with caution in patients with megaloblastic anemia caused by folic acid deficiency.
- Alcohol and Coffee - It is advised to avoid the consumption of beverages such as coffee and alcohol as they cause dehydration.
- Children - Bactrim should not be given to children younger than two months.
- Sunlight - Bactrim can make you sunburn easily. Avoid sunlight and wear protective clothing.
- Elderly - There is a high risk of side effects of Bactrim in the elderly especially those with kidney and liver diseases.
What Are the Side Effects of Bactrim?
Common side effects of Bactrim include
- Loss of appetite.
- Painful or swollen tongue.
- Ringing in the ears.
- Sleep problems.
- Spinning sensation.
Serious side effects include
- Mouth sores.
- Joint aches.
- Bleeding or bruising.
- Severe skin rashes.
- Sore throat.
- Low blood cell count - fever, chills, light-headedness.
- Electrolyte imbalance - headache, chest pain, confusion, loss of coordination or movement.
What Are the Interactions of Bactrim?
Bactrim interacts with drugs, laboratory testing, and food. This can affect the efficacy of the drug and increase the risk of side effects. The drugs should not be stopped or changed without a doctor’s consent.
- Interactions with Other Medicines:
- ACE inhibitors - Benazepril, Enalapril, Lisinopril, Quinapril, Ramipril.
- Antidepressants such as amitriptyline, amoxapine, and desipramine.
- Anticoagulants such as Warfarin.
- With Laboratory Testing:
- The trimethoprim component of Bactrim interferes with a serum methotrexate assay in the CBPA technique.
- Bactrim interferes with the Jaffe alkaline picrate reaction assay and gives false results.
- With Food: When taking as an injection Bactrim, avoid food and drink containing propylene glycol such as in processed foods, and some soft drinks as can increase the risk of side effects.
- With Diseases:
- Urinary obstructive disease- Bactrim should be administered cautiously in patients with urinary retention occurring due to drug accumulation. This may lead to renal toxicity.
- Liver dysfunction- Sulfonamide is partially metabolized in the liver and may accumulate in patients with hepatic impairment.
- Colitis - The antibacterial alters the normal flora of the colon. Bactrim should be administered cautiously in patients with a history of colitis characterized by severe diarrhea and abdominal cramps or passage of blood.
- Hematologic toxicity- Therapy with sulphonamides should be administered cautiously in patients with pre-existing blood dyscrasia and a complete blood count should be obtained regularly.
- Renal dysfunction - Patients with renal impairment are at greater risk for adverse effects due to decreased drug clearance.
- Crystalluria - Patients should be encouraged to consume liquids to maintain urinary outcomes. Sulfonamides cause crystalluria and may cause renal toxicity.
- Porphyria - The use of sulfonamide is contraindicated in patients with porphyria as it may precipitate an acute attack.
What Are the Common Brands of Bactrim?
- Tablet Septran DS 800 mg/160 mg.
- Tablet Alcorim-F 800 mg/160 mg.
- Tablet Clarinic kid 125 mg.
- Tablet Ciplin DS 800 mg /160 mg.
- Tablet Colizole DS 400 mg /80 mg.
- Suspension Kombina.
- Suspension Septran-P.
- Sulfatrim DS 800 mg /160 mg.
- Tablet Altrim 800 mg160 mg.
- Suspension Cotrimox.
Frequently Asked Questions