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TMP-SMX IS NOW PREFERRED FOR PCP PROPHYLAXIS.

Two new trials show that trimethoprim-sulfamethoxazole (TMP-SMX) is the treatment of choice for both primary and secondary prevention of Pneumocystis carinii pneumonia (PCP).

The first, a multicenter Dutch trial, randomized 215 HIV- infected patients at high risk for a first PCP episode (CD4 cell counts below 200/cubic mm) to receive either a monthly dose of aerosolized pentamidine or two daily doses of TMP- SMX (single- or double-strength). After a mean of 264 days, PCP had developed in 11 percent of the pentamidine group and none of the patients treated with TMP-SMX. Twenty-five percent of the TMP-SMX group stopped treatment because of adverse reactions (mainly rash and fever) as compared with 3 percent of pentamidine-treated patients (who mainly had bronchospasm). No marrow toxicity was associated with TMP- SMX. Three cases of toxoplasmic encephalitis occurred, all in the pentamidine group, suggesting that TMP-SMX may have protected against this opportunistic infection.

The second study, a multicenter U.S. trial, randomized 310 patients with AIDS who had recently recovered from PCP to receive aerosolized pentamidine or TMP-SMX (double- strength). Estimated PCP recurrence rates at 18 months were 28 percent with pentamidine versus 11 percent with TMP-SMX. Patients treated with TMP-SMX also had fewer serious bacterial infections. Rates of marrow toxicity and severe rash did not differ between the two treatment groups.

These studies confirm the greater efficacy of TMP-SMX in preventing first or repeat episodes of PCP in HIV-infected patients. TMP-SMX is considerably less expensive than pentamidine and may reduce attack rates of other opportunistic infections. The authors recommend using TMP- SMX as first-line PCP prophylaxis, reserving aerosolized pentamidine for patients who cannot tolerate TMP-SMX.

— ALK

Published in Journal Watch General Medicine December 29, 1992

Citation(s):

Hardy WD et al. A controlled trial of trimethoprim-sulfamethoxazole or aerosolized pentamidine for secondary prophylaxis of Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome. N Engl J Med 1992 Dec 24 327 1842-1848.

• Medline abstract (Free)

Schneider MME et al. A controlled trial of aerosolized pentamidine or trimethoprim-sulfamethoxazole as primary prophylaxis against Pneumocystis carinii pneumonia in patients with human immunodeficiency virus infection. N Engl J Med 1992 Dec 24 327 1836-1841.

• Medline abstract (Free)