Objectives: A randomized clinical trial of low dosage combination of pentamidine and allopurinol was carried out with objectives to assess the efficacy and toxicity as compared to full dosage of pentamidine in antimony unresponsive visceral leishmaniasis (VL) patients.
Methods: Using a randomized control clinical trial, a total of 158 antimony unresponsive patients of VL were randomly allocated into two treatment groups. Patients in one group (n=80) received half the dosage of pentamidine i.e. 2 mg/kg body weight by IM route on alternate day and allopurinol in dose of 15 mg/kg body weight in three divided dosages for 30 days; patients in the second group (n=78) received pentamidine in dose of 4 mg/kg body weight by IM route on alternate day for 15 injections in 30 days. The efficacy and safety of the two regimens were compared.
Results: Apparent cure i.e. clinical and pathological cure at the end of therapy, in 78 (97.5%) and 67 (86%), and ultimate cure i.e. clinical and parasitological cure at the end of follow-up of six months, in 73 (91.25%) and 58 (74.35%) patients was observed in the combination regimen and single regimen group respectively. The difference of the ultimate cure between two groups of the patients was statistically significant (p < 0.01). In single regimen group, 11 (14%) patients showed primary unresponsiveness (with no response during treatment) and nine (13%) relapse (after six months of follow-up) respectively, where as in combination regimen group, two (2.5%) patients showed primary unresponsiveness and five (6.4%) relapse respectively. By the end of the treatment, the incidence of injection-related toxicity, such as rigor and fever, was same in both groups. No hyperglycemia was observed in combination therapy probably due to reduced dose of pentamidine and three patients in single regimen developed hyperglycemia and one of them developed irreversible hyperglycemia.
Conclusions: The study showed that the combination of pentamidine (half dose) and allopurinol is more effective in achieving ultimate cure with an added advantage of reduced toxicity in unresponsive cases as compared to full pentamidine dose.