RESUMEN
Infections caused by hepatitis C virus (HCV) are a significant world health problem for which novel therapies are in urgent demand. The polymerase of HCV is responsible for the replication of viral genome and has been a prime target for drug discovery efforts. Here, we report on the further development of tetracyclic indole inhibitors, binding to an allosteric site on the thumb domain. Structure-activity relationship (SAR) studies around an indolo-benzoxazocine scaffold led to the identification of compound 33 (MK-3281), an inhibitor with good potency in the HCV subgenomic replication assay and attractive molecular properties suitable for a clinical candidate. The compound caused a consistent decrease in viremia in vivo using the chimeric mouse model of HCV infection.
Asunto(s)
Antivirales/síntesis química , Hepacivirus/efectos de los fármacos , Indoles/síntesis química , Oxazocinas/síntesis química , ARN Polimerasa Dependiente del ARN/antagonistas & inhibidores , Proteínas no Estructurales Virales/antagonistas & inhibidores , Administración Oral , Animales , Antivirales/farmacocinética , Antivirales/farmacología , Disponibilidad Biológica , Línea Celular Tumoral , Cristalografía por Rayos X , Perros , Hepacivirus/enzimología , Hepacivirus/fisiología , Humanos , Indoles/farmacocinética , Indoles/farmacología , Macaca mulatta , Ratones , Ratones SCID , Ratones Transgénicos , Modelos Moleculares , Estructura Molecular , Oxazocinas/farmacocinética , Oxazocinas/farmacología , Ratas , Ratas Sprague-Dawley , Estereoisomerismo , Relación Estructura-Actividad , Viremia/tratamiento farmacológico , Viremia/virología , Replicación Viral/efectos de los fármacosRESUMEN
A stability-indicating reversed-phase high performance liquid chromatographic method was developed for the detection of nefopam hydrochloride and its degradation products under accelerated degradation conditions. The degradation kinetics of nefopam hydrochloride in aqueous solutions over a pH range of 1.18 to 9.94 at 90 +/- 0.2 degrees C was studied. The degradation of nefopam hydrochloride was found to follow apparent first-order kinetics. The pH-rate profile shows that maximum stability of nefopam hydrochloride was obtained at pH 5.2-5.4. No general acid or base catalysis from acetate, phosphate, or borate buffer species was observed. The catalytic rate constants on the protonated nefopam imposed by hydrogen ion and water was determined to be 7.16 X 10(-6) M-1 sec-1, and 4.54 X 10(-9) sec-1, respectively. The pKa of nefopam hydrochloride in aqueous solution was determined to be 8.98 +/- 0.33 (n = 3) at 25 +/- 0.2 degrees C by the spectrophotometric method. The catalytic rate constant of hydroxyl ion on the degradation of nefopam in either protonated or nonprotonated form was determined to be 6.63 X 10(-6) M-1 sec-1 and 4.06 X 10(-6) M-1 sec-1, respectively. A smaller effect of hydroxyl ion on the degradation of nonprotonated than on the degradation of protonated nefopam was observed.(ABSTRACT TRUNCATED AT 250 WORDS)