Toxoplasma encephalitis: Influence of the vehicle on the efficacy of different doses of 2 ',3 '-dideoxyinosine in mice

In this study we investigated the effect of the antiretroviral molecule 2', 3'-dideoxyinosine (Videx(R)) against cerebral cysts in a murine model of to xoplasmic encephalitis caused by a wild cystic strain of Toxoplasma gondii. The role of the vehicle was also studied. Three doses were used: 50, 100 a nd 150 mg/kg of body weight/day. The doses of 50 and 150 mg/kg were prepare d by dissolving pure 2',3'-dideoxyinosine powder in Maalox(R) suspension be fore gavaging the mice; the dose of 100 mg/kg was prepared by grinding tabl ets of Videx(R) that were suspended in water. A decrease in the number of c ysts and a morphological modification of them were noted from day 15 with t he lowest dose. The most important decrease could be observed with the dose of 100 mg/kg/d. After 30 days of treatment with this dose, 65% of the cyst s were destroyed compared to controls. For the doses of 50 and 150 mg/kg/d prepared with Maaloxo(R) 36% and 51% of the cysts were destroyed respective ly. So ddl hers an effect on the cerebral cysts of T. gondii even at a low dose. The galenic formulation influences its action since the doses prepare d with Maalox(R) were less efficient than those prepared from ground tablet s.