A Study of Neutrexin Plus Leucovorin in the Treatment of Pneumocystis Carinii Pneumonia (PCP)

Inclusion Criteria Concurrent Medication: Allowed: * Myelosuppressive or nephrotoxic agents at the discretion of the treating physician. Patients must have: * Pneumocystis carinii pneumonia (PCP) confirmed within 15 days prior to study entry. * Serious intolerance and/or resistance to standard therapies (such as trimethoprim/sulfamethoxazole and parenteral pentamidine) during the course of therapy for the current episode of PCP, or a documented history of such intolerance during a prior episode. * Consent of parent or guardian if less than 18 years of age. NOTE: * Pregnant women may enroll after the physician and patient have discussed the potential benefit versus risk. Exclusion Criteria Patients with the following prior conditions are excluded: History of Type I hypersensitivity (i.e., urticaria, angioedema, or anaphylaxis), exfoliative dermatitis, or other life-threatening reactions due to trimetrexate glucuronate.