National Shortage of Pyrimethamine: Pyrimethamine/sulfadiazine is the first line agent with established clinical efficacy for the management of toxoplasmosis encephalitis [CID 1996; 22:268] The national shortage of pyrimethamine is due to manufacturing problems; however, the manufacturer expects the drug to be available on September 21st [personal communication Glaxo, 9/4/2001]

The only other available source of pyrimethamine is Fansidar, a combination of pyrimethamine and sulfadoxine. Each tablet of Fansidar contains 25 mg of pyrimethamine and 500 mg of sulfadoxine. Sulfa rechallenge may be considered in patients with a mild allergic reaction to sulfa drugs. Alternative drugs with demonstrated in vitro activity against Toxoplasma gondii include azithromycin, atovaquone, trimetrexate, and doxycycline. However, clinical data on non-pyrimethamine containing regimens are lacking.

The recommendations listed below are based on in vitro activity, drug availability, and author's opinion.

Alternative Management of Toxoplasmosis Encephalitis

• Acute Infection: Fansidar 4 tablets (100 mg pyrimethamine/2 gm sulfadoxine) x1, then 2 tablets (50 mg pyrimethamine/1 gm sulfadoxine) PO qd plus sulfadiazine 1 gm q6h plus folinic acid 10 mg PO qd.
• Suppressive Therapy: Fansidar 1 tablet (25 mg pyrimethamine/500 mg sulfadoxine) plus sulfadiazine 500 mg q6h plus folinic acid 10 mg PO qd.
  

Alternative Management of Toxoplasmosis Encephalitis in Sulfa-allergic Patient

• Acute infection: Azithromycin 900 mg PO x2 first day, then 1200 mg/day x 6 weeks or Trimetrexate 45 mg/m2 qd plus folinic acid 20 mg/m2 + clindamycin 900 mg IV q6h or 450 mg PO q6h x 6 weeks or Azithromycin 900 mg PO x2 first day, then 1200 mg/day + clindamycin 900 mg IV q6h or 450 mg PO q6h x 6 weeks.
• Suppressive Therapy: Azithromycin 600 mg PO qd +/- clindamycin 300-450 mg PO q6h +/- atovaquone liquid 1500 mg PO qd.

By: Paul A. Pham, Pharm.D., B.C.P.S.
posted 9/17/2001

back to news table of contents