Can diabetes mellitus modify the plasma concentrations of rifampicin in patients under treatment for tuberculosis?

Abstract Rifampicin is a key component of treatment for tuberculosis and its efficacy is determined by the blood levels attained after therapeutic doses. However, there is a high variability of rifampicin blood levels that is related to both the patient and the formulation used. To date, the effect of diabetes mellitus on the plasma levels of rifampicin was low exploited, which could be relevant either by the significant increase of the comorbidity worldwide as by the probable influence of diabetes on the rifampicin exposure. The study aims to evaluate whether diabetes mellitus contribute to the variation of the maximum concentration of rifampicin in patients with tuberculosis treated with a daily dose of 10 mg/kg. Rifampicin and glycated hemoglobin were measured by high-performance liquid chromatography, and blood glucose by spectrophotometry. A total of 62 male patients were included in the study, and 26 presented diabetes mellitus. Rifampicin plasma levels in 2-h plasma samples collected at day 61 ranged from 3 µg/mL to 14.2 µg/mL. Drugs levels were similar between diabetic and non-diabetic patients and were not correlated with blood glucose and glycated hemoglobin. Moreover, a high percentage of patients in both groups presented low levels of rifampicin.

Concentrations of rifampicin in pre-dose samples in patients with pulmonary tuberculosis

ABSTRACT Rifampicin is used in both phases of treatment for tuberculosis. In chronic use, the short half-life and the self-induction of metabolism can decrease the levels of the drug below the minimal inhibitory concentration. The aim of the study was to investigate whether plasma concentrations of rifampicin are sustained above 0.5 µg/mL in patients with tuberculosis using 600 mg/day. Rifampicin was measured in plasma by high-performance liquid chromatography and a sputum smear microscopy was performed in all days of the study. A total of 44 male patients completed the study. On days 31, 61 and 91, the mean plasma concentrations of rifampicin were 0.6 (0.5) µg/mL, 0.55 (0.5) µg/mL and 0.46 (0.4) µg/mL. There was a high variation of rifampicin levels leading to a high percentage of samples with concentrations below 0.5 µg/mL. There was no significant association between the frequency of samples with drug levels below 0.5 µg/mL with the conversion of the sputum microscopy. These data suggest that pre-doses samples offer limited information on the exposure of M. tuberculosis to rifampicin.

Validación de un método de cromatografía líquida para la determinación de rifampicina en plasma humano / Validation of a liquid chromatography method for rifampicin determination in human plasma

Objetivos: Validar un método de cromatografía líquida de alta resolución (HPLC) para la determinación de rifampicina (RFP) en plasma humano. Materiales y métodos. Se desarrolló un método HPLC para la determinación de RFP en plasma. La separación fue realizada por cromatografía de fase reversa con una columna C18 y una fase móvil compuesta por una mezcla de acetonitrilo y solución amortiguadora de fosfato de potasio monobásico 0,05 M (38:62 v/v) a 335 nm. En el cual se empleó como estándar interno rifampicina quinona (RFP-QN). Resultados. Los tiempos de retención de RFP y RFP-QN fueron 7,81 y 12,26 minutos, respectivamente. El ensayo fue lineal de 0,5 a 250 ug/mL Los parámetros evaluados de precisión, exactitud, selectividad, linealidad, recuperación cumplieron con lo establecido en las guías internacionales de validación de métodos bioanalíticos. Conclusiones. El método HPLC desarrollado es simple, específico, sensible, selectivo y lineal para un amplio rango de concentraciones de RFP en plasma.

Objectives: To validate the high-performance liquid chromatography method (HPLC) for rifampicin (RFP) determination in human plasma. Materials and methods. A HPLC method for RFP determination in plasma was developed. The separation was performed by reversed-phase chromatography with C18 column and a mobile phase composed of a mixture of acetonitrile and monobasic potassium phosphate buffer solution 0.05 M (38:62 v/v) at 335 nm in which standard rifampicin quinone (RFP-QN) was used. Results. The retention times of RFP and RFP-QN were 7.81 and 12.26 minutes, respectively. The trial was linear from 0.5 to 250 ug/mL. The evaluated parameters of precision, accuracy, selectivity, linearity, and recovery complied with the established international standards for validation of bioanalytical methods. Conclusions. The developed HPLC method is simple, specific, sensitive, selective and linear for a wide range of RFP concentrations in plasma.