Plasma antimony determination during cutaneous leishmaniasis treatment with intralesional infiltration of meglumine antimoniate

Objectives: To evaluate the antimony (Sb) in plasma of patients who underwent a standardised meglumine antimoniate (MA) intralesional infiltration protocol for cutaneous leishmaniasis treatment.

Methods: The level of Sb in plasma was determined by atomic absorption spectroscopy, before and 1, 2, 4 and 6 hours after the first intralesional infiltration of MA to determine the parameters peak concentrations (C_{1 h} )_, area under curve of drug concentration in plasma from zero to 6 h (AUC_{0-6 h} ) and elimination half-life (t½) of Sb. Blood samples were also collected weekly during the treatment period, always before infiltration.

Results: Fourteen patients underwent MA intralesional infiltration with doses ranging from 0.8 to 9 mg Sb/kg at the first infiltration. The C_{1 h} ranged from 3850 to 47 095 mg × h/L and was the highest concentration obtained for 11 of 14 patients after the first intralesional infiltration of MA. A rapid initial phase of distribution lasting up to 4 h (2.6 ± 0.34 h) was followed by a slower elimination phase. Total skin lesion area, C_{1 h} and AUC_{(0-6 h)} were related to the dose of Sb infiltered (P < 0.05). Plasma Sb in samples collected weekly before the infiltration revealed antimony concentrations below the quantification limit (15.0 μg Sb/l) during the treatment period.

Conclusions: Sb is quickly absorbed and eliminated after intralesional administration of MA, in a pattern similar to that reported with the Sb systemic administration. Using a therapeutic schedule limited to weekly intralesional infiltration of doses <10 mg Sb/kg does not result in plasma Sb accumulation.