Study On The Structure And Quality Of Pregabalin

Pregabalin is a novel gamma-aminobutyric acid(GABA)analogue receptor agonist for the treatment of neuropathic pain, partial-onset seizures, and anxiety disorders. In December 2004 the US Food and Drug Administration (FDA) approved pregabalin for the treatment of neuropathic pain associated with diabetic peripheral neuropathy and postherpetic neuralgia. Mechanism of action is that pregabalin as a ligand bonding to the alpha2-delta subunit which relate to the voltage-dependent calcium channels and by regulating of these channels decrease calcium into nerve endings, resulting in a decreased release of several excitatory neurotransmitters. It does not bind to plasma proteins, no liver metabolism, and excretion by the kidney, the analgesic effects of Pregabalin occur in the first few days of treatment and are sustained over time.side effects are few, most are transient and well-tolerated by patients. Since quality standard of pregabalin and its preparations have not been recorded into internal or overseas pharmacopeia, Pregabalin hadn't come into the domestic market yet. A quality standard of the Pregabalin was established on the basis of the studying on the Pregabalin developed by Chongqing pharmaceutical research institute (CPRI).Crystalline Pregabalin was designed and synthesized by CPRI, in this article, the structure of crystalline Pregabalin was conformed by using a series of spectral techniques which including UV, IR, MS, NMR. To conform the spatial configuration of Pregabalin by derivatization and contrasted with the Foreign Drugs. The research focuses on studying of systematical measuring methodology of related substances, optical isomer, residual solvents and assay of Pregabalin.To establish HPLC methods for the limit test of the related substance of Pregabalin, the chromatogratophic procedure was carried out using a stainless steel column packed with octadecyl (Aichrombond AQ-C18, 250×4.6mm,5μm),as the mobile phase with a flow rate of 1.ml per minute a mixture of 95 volumes of phosphate buffer(Dissolve 0.12g of potassium dihydrogen phosphate and 0.56g of disodium hydrogen phosphate in 1 L of water.) and 5 volumes of acetonitrile, and as a detection wavelength of 205nm. The numbers of theoretical plates are not less than 1500. The method has good specification, and the main intermediatesis and degradation products can be separated sufficiently.A new GC method was established to detected organic solvent residues which including dichloromethane, tetrahydrofuran, toluene, isopropanol, isovaleral, acetidin and diethyl malonate. The resolutions were comply with the requirements of China Pharmacopoeia and ICH.Na-(5-fluoro-2,4-dinitrophenyl)- 5-L-alanine amide(FDNPPA) was pre-column derivatization regent which can reaction with pregabalin (molar ratio not less than 2.96)and produce a compound that can be successfully separated the optical isomer of Pregabalin by reversed-phase high performance liquid chromatographic. Following conditions were used as chromatogratophic procedure:(a) a Inertsil ODS-2 column (5μm,250mm×4.6mm) was used as analytic column, the mobile phase is a mixture of 55 volumes of triethylamine buffer (Dissolve 7.0ml of triethylamine in 1000ml of water, ajust pH to 3.0 by Phosphoric acid) and 45 volumes acetonitrile and the flow rate is 1.0ml/min. The derivatives of pregabalin were separated under the established HPLC conditions with the resolution factor being not less than 4.0 and the limit of detection is 3.79×10-8g/ml(S/N=3). The method has good accuracy and repeatability, can be used for the quality control of Pregabalin.The chromatogratophic procedure of assay of Pregabalin was carried out using a stainless steel column packed with octadecyl (Aichrombond AQ-C18, 250×4.6mm,5μm),as the mobile phase with a flow rate of 1.ml per minute a mixture of 95 volumes of phosphate buffer(Dissolve 0.12g of potassium dihydrogen phosphate and 0.56g of disodium hydrogen phosphate in 1 L of water.) and 5 volumes of acetonitrile, and as a detection wavelength of 205nm.. The method has good specification, the limit of detection is 1.890×10-7(g/ml), between 0.2082mg/ml～1.6656mg/ml has good linearity, the linear equation is A=730.20C+4.608 (A-HPLC area, C-μg/ml), the relativity coefficient is 1.0,and the RSD is 0.3%.Through the above study, developed in comply with the relevant technical requirements of the clinical treatment Pregabalin quality standards.