Development of a Method for Identification and Quantification of Sulfadiazine and Pyrimethamine in Serum of Congenital Toxoplasmosis Pediatric Patients

Infection with Toxoplasma gondii, is one of the most widespread zoonoses in the world. Congenital Toxoplasmosis (CT) is particularly risky due to its fetal complications. Sulfadiazine (SDZ) and Pyrimethamine (PYR) are usually used for CT treatment in Argentina, to prevent morbidity. Due to the lack of commercial pediatric formulations, these must be prepared in the hospital pharmacy. This is the first report of serum concentrations measures in pediatric CT therapy for this combination of drugs. A bioanalytical method was developed for identification and simultaneous quantification of SDZ and PYR by High Performance Liquid Chromatography (HPLC) with UV detection. The validated method was applied to residual serum samples obtained from 6 pediatric patients undergoing treatment with SDZ 42.20 a 93.70 mg/kg/day and PYR 0.77 a 2.70 mg/kg/day. Sample pretreatment consisted on a deproteinization step followed by centrifugation and then injection of supernatant. Limit of Detection (LOD) and Quantification (LOQ) were (0.17 ± 0.02 and 0.13 ± 0.02) μg/mL and (0.46 ± 0.01 and 0.36 ± 0.01) μg/mL for SDZ and PYR respectively, with an appropriate linear range. Concentrations range found were ( - 162.04 ± 0.02) μg/mL for SDZ and ( - 7.30 ± 0.03) μg/mL for PYR. We developed and validated in real pediatric samples, an acute, precise and low-cost method for quantification of SDZ and PYR using a non-sophisticate chromatographic equipment, suitable for hospital therapeutic monitoring for public health system.