Sulphadiazine


Sulphadiazine combined with pyrimethamine is the most effective first-line treatment of cerebral toxoplasmosis in AIDS patients (sulphadiazine 1-1.5 g q 6 hours p.o. x 6 weeks + pyrimethamine 100-200 mg loading dose, then 50-75 mg / day p.o. x 6 weeks + leucovorin 10-20 mg / day p.o.).

Incidence
High, but no accurate findings.

 

Risk factors
AIDS.

Clinical manifestations
General: fever (10%), conjunctivitis.

Cutaneous: rash (19%): maculoerythematous or morbilliform ; itching, facial angioedema, Stevens-Johnson’s syndrome.

Haematological: leukopenia (40%), thrombocytopenia (12%).

 

Diagnostic methods
Cutaneous testing.

Skin-prick tests (1 mg/ml, 2 mg/ml, 5 mg/ml) are negative.

No specific histamine release.

 

Mechanisms
See sulfamethoxazole-trimethoprim.

 

Management
Alternative therapy

Replace sulphadiazine with clindamycin, azithromycin, clarithromycinor atovaquone

Desensitization: 2 different protocols have been published:

 

1°- Oral route in 5 days +/- corticosteroids

Day 1: 10 µg to 200 µg

Day 2: 300 µg to 8 mg

Day 3: 15 mg to 500 mg

Day 4: 500 mg: 1 x 4 / day

Day 5: 500 mg: 2 x 4 / day

Success rate: 62%

 

2°- Oral route in 10 days without corticosteroids

Day 1: 5 mg and 10 mg

Day 2: 20 mg and 40 mg

Day 3: 80 mg and 160 mg

Day 4: 250 mg and 500 mg

Day 5: 750 mg and 750 mg

Day 6: 1 g and 1 g

Day 7: 1 g/8 hours

Day 8: 1g/6 hours

Day 9: 1.5 g/6 hours

Day 10: 2 g/6 hours

Success rate: 100%

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.