[Primary prophylaxis against cerebral toxoplasmosis. Efficacy of folinic acid in the prevention of hematologic toxicity of pyrimethamine].

OBJECTIVES

Cerebral toxoplasmosis is the most frequent opportunistic infection in patients with acquired immune deficiency syndrome in France. We evaluated the effect of adding folic acid to the standard treatment (including pyrimethamine) on preventing induced cytopenia in order to determine the optimal dose.

METHODS

From January to September 1990, pyrimethamine (50 mg 3 times per week) was given as primary prophylaxis against toxoplasmosis to 30 patients who were positive for human immunodeficiency virus (CDC classes II or II, CD4 counts < 200/mm3). The patients were randomly divided into three groups given 5, 25 and 0 mg folic acid 3 times per week. Associated treatments were the same in all patients (zidovudine 600 mg/d, pentamidine isethionate aerosol, 300 mg, once a month). Blood cell counts and lymphocyte subset counts were made on days 0, 30, 90 and 180.

RESULTS

Two patients were lost to follow-up and between day 90 and 180, 3 were excluded due to other opportunist infection and 1 due to zidovudine induced anaemia. Between the groups, there was no difference in haemoglobin level or cell counts on day 0. No haematologic toxicity was observed at day 90. Haemoglobin was significantly reduced in the control group (0 mg folic acid) on day 180 (mean haemoglobin on day 180, 13.8, 13.1 and 12.1 g/dl in groups 1, 2 and 3 respectively). No variation in polynuclear neutrophil counts was observed.

CONCLUSION

These findings suggest that folic acid has a moderate beneficial effect on preventing haematologic disease in patients treated with pyrimethamine. There was no observed dose effect.