ABSTRACT
Using rapid centrifugal filtration (Subject(s)
Chromatography, High Pressure Liquid/methods
, Pharmaceutical Vehicles/chemistry
, Polysaccharides, Bacterial/analysis
, Rheology/methods
, Calibration
, Centrifugation/methods
, Filtration/methods
, Limit of Detection
, Viscosity
ABSTRACT
2-(1,1-Dioxo-2H-[1,2,4]benzothiadiazin-3-yl)-1-hydroxynaphthalene derivatives as potential anti-HCV drugs targeting NS5B polymerase have been investigated. Their synthesis, HCV NS5B polymerase inhibition and replicon activity are discussed.
Subject(s)
Antiviral Agents/chemical synthesis , Benzothiadiazines/chemical synthesis , Enzyme Inhibitors/chemical synthesis , Hepatitis C/drug therapy , Naphthalenes/antagonists & inhibitors , Naphthols/chemical synthesis , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/pharmacology , Benzothiadiazines/pharmacology , Chemistry, Pharmaceutical/methods , Drug Design , Enzyme Inhibitors/pharmacology , Hepacivirus/metabolism , Humans , In Vitro Techniques , Inhibitory Concentration 50 , Magnetic Resonance Spectroscopy , Models, Chemical , Molecular Structure , Naphthalenes/chemistry , Naphthols/pharmacology , Structure-Activity RelationshipABSTRACT
1-(3,4-Dimethoxyphenyl)-4-methyl-5-ethyl-7,8-dimethoxy-5H-2,3-benzodiazepine (tofisopam) contains one chiral center, so two enantiomeric forms exist. The ring system of tofisopam possesses two sterically stable boat structures, leading to two distinct conformers for each enantiomer. A method was developed for the separation of these enantiomers and conformers in the drug substances and drug products. Separation was achieved with a separation factor of at least 3.9 for any adjacent peaks. Validation of the method challenged linearity, limit of detection, limit of quantification, specificity, accuracy, repeatability, intermediate precision, robustness, and stability of standard and sample solutions, and all validation results met the acceptance criteria. A study of accuracy at 80%, 100%, and 120% levels gave recoveries of 100 +/- 1%. The RSD of six sample injections for repeatability was less than 0.5%. The detection limit of tofisopam enantiomer was as low as 0.12 microg/mL. The kinetics and thermodynamics of the interconversion of tofisopam conformers were also investigated, and the kinetic and equilibrium constants of the interconversion process were determined at 15 degrees C, 25 degrees C, and 35 degrees C.