Development and validation of a stereoselective HPLC method for the determination of thein vitro transport of nateglinide enantiomers in rat intestine

Analytical tools for determination of new oral antidiabetic drugs, glitazones, gliptins, gliflozins and glinides, in bulk materials, pharmaceuticals and biological samples

The review presents analytical methods for determination of new oral drugs for the treatment of type 2 diabetes mellitus (T2DM), focusing on peroxisome proliferator-activated receptor gamma agonists (glitazones), dipeptidyl peptidase 4 inhibitors (gliptins) and sodium/glucose co-transporter 2 inhibitors (gliflozins). Drugs derived from prandial glucose regulators, such as glinides, are considered because they are present in some new therapeutic options. The review presents analytical procedures suitable for determination of the drugs in bulk substances, such as pharmaceuticals and biological samples, including HPLC-UV, HPLC/LC-MS, TLC/HPTLC, CE/CE-MS, spectrophotometric (UV/VIS), spectrofluorimetric and electrochemical methods, taken from the literature over the past ten years (2006-2016). Some new procedures for extraction, separation and detection of the drugs, including solid phase extraction with molecularly imprinted polymers (SPE-MIP), liquid phase microextraction using porous hollow fibers (HP-LPME), HILIC chromatography, micellar mobile phases, ion mobility spectrometry (IMS) and isotopically labeled internal standards, are discussed.

Stereoselective binding of chiral anti-diabetic drug nateglinide to plasma proteins

The binding of nateglinide (NA) enantiomers with human plasma (HP), human serum albumin (HSA) and bovine serum albumin (BSA) was investigated. The protein binding was studied over a drug concentration range of 5-100 μM at a protein concentration of 600 μM. Unbound drug concentrations were determined by direct chiral liquid chromatography using chiralcel OJ-RH column. At therapeutic drug concentrations, the protein binding of each enantiomer was >98%. The results showed that the binding of NA enantiomers was stereoselective, mutually competitive and non-linear. The binding characteristics were, however, opposite for the two most important plasma binding proteins. Opposite stereo-selectivity was observed between BSA and HSA while stereo-selectivity was identical between HSA and HP. Scatchard analysis was used to illustrate the different binding affinities of NA enantiomers to BSA, HSA and HP. The interaction between enantiomers observed in HP and serum albumins was confirmed as a competitive type interaction at the high affinity site. Scatchard analysis was used to illustrate the different binding affinities of NA enantiomers to BSA, HSA and HP.

Determination of the L-enantiomer of nateglinide in pharmaceutical formulations by micellar electrokinetic chromatography

An analytical micellar electrokinetic chromatographic method was developed and validated for the determination of the L-enantiomer of nateglinide. Separations were carried out in a 50 μm, 64.5/56 fused-silica capillary. The optimized conditions included 75 mM borate buffer, pH 9.2, containing 50 mM of sodium dodecyl sulfate and 25 mg/mL of methyl-β-cyclodextrin as background electrolyte, an applied voltage of 20 kV and a temperature of 15, UV detector at 210 nm. The assay was validated for the L-enantiomer of nateglinide. The limit of detection and quantification were 0.07 and 0.2% respectively. Intraday precision was ranged between 0.12 and 1.7%. Interday precision ranged between 0.73 and 1.73%. The assay was applied to the determination of the L-enantiomer of nateglinide in pharmaceutical formulations.