TMP/SMX (Bactrim, Septra)

Drug description
Trimethoprim/sulfamethoxazole is the chemical name for a commonly used compound of two antibiotics. One of the manufacturersí brand names is Bactrim. Bactrim has been safely and effectively used for many years to treat common respiratory infections, and is also prescribed to people who have sinusitis. Bactrim is used for prevention and treatment of PCP pneumonia. Oral Bactrim is delivered throughout the body and is evenly spread throughout lung tissue. Bactrim may be effective in preventing and treating some other infections that occur in HIV disease, such as toxoplasmosis, salmonella, shigella, and sinusitis. Glaxo-Wellcome, Inc., who makes Septra, has an HIV Patient Assistance Program that can be reached at (800) 722-9294. Hoffman-La Roche, Inc., who makes Bactrim, has a Reimbursement Assistance program. Call (800) 443-6676.

Side effects
Like other sulfa drugs, Bactrim can cause allergies, fever, nausea, and vomiting. Allergies typically develop as a widespread itchy red rash with fever eight to fourteen days after beginning the standard dose of Bactrim. Neutropenia, a reduction in the number of neutrophils, can also occur.

Dosage
A commonly prescribed dose for PCP prevention is one double-strength tablet of Bactrim taken twice a day, three days a week.

How long it may take to work
Preventive therapy is ongoing. Preventive treatment means you keep taking the drug to prevent an infection so that you don't become ill. Treatment for active infection is 2 to 3 weeks. Bactrim may take five to seven days to produce clinical improvement.

Managing side effects
Dosages of AZT, ganciclovir, acyclovir and some drugs used as chemotherapy against cancer may need to be reduced if given in combination with Bactrim to avoid neutropenia. Allergic symptoms such as rash and fever will go away by themselves within a few days after stopping Bactrim. Rash can be reduced by using Benadryl. Corticosteroids, a class of drugs that are powerful suppressants of allergic reactions, can be used if the reaction is especially severe. Notify your doctor if a rash develops. If you are allergic to Bactrim, you may be able to tolerate the drug if you start again at very small doses and then build up gradually. This is called desensitization. Recent studies have shown that around 85% of people who have a reaction at first can be desensitized to this drug.

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