Potent anti-murine cytomegalovirus activity and reduced nephrotoxicity of ganciclovir cyclic phosphonate

Ganciclovir cyclic phosphonate (SR3775) is a derivative of the R enantiomer (SR3773) of ganciclovir phosphonate (9-[((+/-)-1-hydroxymethyl-3-phosphono)propyloxymethyl]guanine), both of which are potent inhibitors of human ctyomegalovirus and murine cytomegalovirus (MCMV). Against wild-type and four drug-resistant strains of MCMV, SR3773 was 2.3- to 3-fold more potent than SR3775. SR3775 was about half as active as SR3773 against MCMV infections in severe combined immunodeficient mice. However, whereas SR3773 caused 20 to 30% destruction of renal tubules at 50 mg/kg of body weight per day (but exerted no toxicity at 25 mg/kg/day), SR3775 showed no deleterious renal effects at 600 mg/kg/day over 14 days. SR3775 has a therapeutic index at least 12 times higher than SR3773 in mice, making it a candidate for the treatment of human cytomegalovirus disease.

Pharmacological immunosuppression in clinical organ grafting. Observations on four agents: cyclosporin A, Asta 5122 (cytimun), lambda carrageenan and promethazine hydrochloride

In this article I have attempted to summarize experiments on four agents investigated for immunosuppressive activity in experimental and clinical organ grafting. The difficulty of finding a suitable laboratory model relevant to man has been demonstrated in this experience. A cyclophosphamide-derivative, Asta-5122 (cytimun), has only a marginally superior immunosuppressive activity in a dog with a renal allograft compared with cyclophosphamide and is much inferior to azathioprine. This agent, however, appears to be valuable in clinical practice in patients with liver grafts. A combination of lambda carrageenan, promethazine hydrochloride and imuran has profound immunosuppressive activity in the same canine model, but proved to be both ineffective and potentially toxic in a limited trial in man. The fungal cyclic peptide, cyclosporin A, has been shown to be an extremely powerful immunosuppressive agent and remarkably non-toxic in dogs with renal allografts and pigs with orthotopic heart grafts. This agent is currently being investigated as an immunosuppressant in patients with organ grafts.

[Toxicity and antitumor activity of the antibiotic rubomycin and dipin in combination with diuretics (diacarb)]

Rubomycin or dipin in combination with diacarb had higher toxicity and antitumor activity as compared to administration of the cytostatic agents alone to mice with transplanted lymphosarcoma, strain L10-1. The chemotherapeutic indices of the combinations did not differ or were somewhat lower as compared to the same indices of the cytostatic agents used alone.