Adverse drug reactions to treatments for ocular toxoplasmosis: a retrospective chart review.

OBJECTIVE

This study evaluated the incidence and types of adverse drug reactions (ADRs) associated with medications used to treat active toxoplasmic chorioretinitis.

METHODS

This was a retrospective review of the clinical records of a consecutive series of patients with active toxoplasmic chorioretinitis, examined between March 1991 and August 1998. For inclusion in the review, patients had to have been diagnosed with active toxoplasmic chorioretinitis, been treated with a single drug or drug combination indicated for this condition, and been followed for at least 8 weeks. Patients who were lost to follow-up or who had incomplete chart data were excluded. Demographic data, pertinent aspects of the medical history, drug treatments, and ADRs associated with antitoxoplasmic treatment were recorded.

RESULTS

Fifty-five patients met the criteria for inclusion in the review. In descending order of frequency, they received antitoxoplasmic treatment with clindamycin (n = 50), sulfadiazine (n = 40), pyrimethamine (n = 33), trimethoprim-sulfamethoxazole (n = 16), and atovaquone (n = 10), alone or in combination. Twenty-two patients (40.0%) had a total of 27 ADRs. The most frequently occurring ADRs were rash (19 [34.5%]), mostly associated with sulfadiazine (9/40 [22.5%]) and clindamycin (6/50 [12.0%]), and gastrointestinal ADRs such as diarrhea (6 [10.9%]), stomach upset (6 [10.9%]), and bleeding (1 [1.8%]), mostly associated with clindamycin (5/50 [10.0%], 3/50 [6.0%], and 1/50 [2.0%], respectively). The incidence of ADRs associated with individual antitoxoplasmic drugs was 30.0% (3/10) for atovaquone, 26.0% (13/50) for clindamycin, 22.5% (9/40) for sulfadiazine, 12.5% (2/16) for trimethoprim-sulfamethoxazole, and 12.1% (4/33) for pyrimethamine. There were 2 serious ADRs: gastrointestinal bleeding in a patient treated with clindamycin and leukopenia in a patient treated with pyrimethamine. Twenty-five ADRs were reversed on drug discontinuation; the remaining 2 were mild and did not require drug discontinuation.

CONCLUSIONS

The overall incidence of treatment-associated ADRs was high (40.0%) in these patients with ocular toxoplasmosis. The most frequently occurring ADRs were rash and gastrointestinal complaints.