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Objective: Isoniazid (INH) is a major antituberculosis treatment, characterized by a narrow therapeutic index and a large within and between-patient variability. Thus, Therapeutic Drug Monitoring (TDM) of this drug is mandatory in order to optimize the efficacy and minimize occurrence of toxic side effects of this drug. The aim of the present study is to develop and validate a simple chromatographic method for determination of INH in human plasma. Methods: High performance liquid chromatography was performed using a chromatograph Ultimate 3000®. The extraction of INH from plasma was realized using trichloroacetic acid (TCA). Nicotinamide was used as an internal standard (IS). The mobile phase consisted of the buffer solution ammonium acetate (99%) 0.05 M adjusted by glacial acetic acid to pH 6 (99%), and acetonitrile (1%). The chromatographic separation was achieved on a C18 column (5 μm, 4.6 x 150 mm) at 20 °C. The signals were monitored by Diode Array Detector (DAD) at wavelength (λ) of 265 nm, at a flow rate of 1.2 ml/min. Results: The retention times of INH and IS were 6.4 and 10.5 respectively. The limits of detection and quantification of INH were 0.09 and 0.3 μg/ml, respectively. This present method is specific and linear over the range of 0.5 to 8 μg/ml with regression coefficient of 0.998. Additionally, this method is accurate and precise, as shown by appropriate statistical tests recommended for bioanalytical methods’ validation. Conclusion: We developed and validated a simple, rapid and convenient method for plasma INH determination in tuberculosis patients receiving this treatment.

HLA-G is believed to act as an anti-inflammatory molecule in Multiple Sclerosis (MS). The 3′ untranslated region of the HLA-G gene is characterized by two polymorphisms, DEL/INS14bp and +3142C>G, which control soluble HLA-G (sHLA-G) production. The influence of these two HLA-G variants on sHLA-G serum and cerebrospinal fluid (CSF) levels was investigated in 69 Relapsing-Remitting MS patients grouped in magnetic resonance imaging (MRI) inactive and active disease. Serum and CSF sHLA-G levels were more elevated in high than in low DEL/INS 14bp and +3142C>G sHLA-G producers and were different among the various combined HLA-G genotypes in both MRI inactive and active diseases. The highest and the lowest sHLA-G values were identified in MS patients with C/C,DEL/DEL and G/G,INS/INS genotypes, respectively. Our preliminary findings suggest that serum and CSF sHLA-G levels in MS could be influenced by HLA-G polymorphisms irrespective of the inflammatory microenvironment.