TreatmentUpdate 74 - Volume 8, No 10; December 1996
Sean Hosein

Bactrim/Septra (B/S) is considered the best product for preventing the appearance of the life-threatening lung infection PCP (Pneumocystis carinii Pneumonia). Unfortunately some people with HIV/AIDS (PHAs) seem unusually sensitive to the drug -- between "44% to 69% [can have] skin rash, nausea and fever."

Doctors have developed a programme for people who are sensitive to B/S in order to reduce the risk of hypersensitive reactions. Doctors first prescribe a very small dose of the drug then rapidly increase the dose so that within 2-3 days PHAs can take the standard dose. This process is called desensitization. Several desensitization protocols have appeared in past issues of TreatmentUpdate. These protocols are important because B/S can protect PHAs from bacterial pneumonia, toxo (toxoplasmosis), PCP and perhaps MAC (Mycobacterium avium complex). However, doctors in San Francisco report other side effects in their patients who use B/S.

Problems

The doctors reported that the PHAs had all been desensitized to B/S and had less than 50 CD4+ cells. Between 6 and 8 weeks after using B/S they began to develop bone marrow damage. Lab tests showed that most subjects had very low levels of white and, in some cases, red blood cells. At least one PHA felt very tired and another's immune system began to attack his red blood cells.

Once the PHAs stopped using B/S and received the bone marrow stimulants filgrastim (G-CSF; granulocyte-colony stimulating factor, Neupogen ) and/or EPO (erythropoietin), they recovered in about 3 weeks. The doctor aren't sure what caused these complications, although non-HIV-infected subjects who use sulfa drugs have been known to develop bone marrow damage. After subjects recovered they received other treatments to prevent PCP including infusions of pentamidine or dapsone 100 mg thrice weekly.

REFERENCES:

1. Stricker RB, Gullett JH, Williams LE and Goldberg B. Co-trimoxazole desensitization syndrome: delayed haematologic toxicity complicating prophylactic therapy in AIDS patients. AIDS 1996;10(8):927-929.

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