RESUMEN
Facilitating activation, or delaying inactivation, of the native Kv7 channel reduces neuronal excitability, which may be beneficial in controlling spontaneous electrical activity during epileptic seizures. In an effort to identify a compound with such properties, the structure-activity relationship (SAR) and in vitro ADME for a series of heterocyclic Kv7.2-7.5 channel openers was explored. PF-05020182 (2) demonstrated suitable properties for further testing in vivo where it dose-dependently decreased the number of animals exhibiting full tonic extension convulsions in response to corneal stimulation in the maximal electroshock (MES) assay. In addition, PF-05020182 (2) significantly inhibited convulsions in the MES assay at doses tested, consistent with in vitro activity measure. The physiochemical properties, in vitro and in vivo activities of PF-05020182 (2) support further development as an adjunctive treatment of refractory epilepsy.
Asunto(s)
Descubrimiento de Drogas , Epilepsia/tratamiento farmacológico , Activación del Canal Iónico/efectos de los fármacos , Canal de Potasio KCNQ2/metabolismo , Piperidinas/farmacología , Pirimidinas/farmacología , Animales , Línea Celular , Relación Dosis-Respuesta a Droga , Electrochoque , Humanos , Canal de Potasio KCNQ2/agonistas , Microsomas/efectos de los fármacos , Estructura Molecular , Piperidinas/administración & dosificación , Piperidinas/química , Pirimidinas/administración & dosificación , Pirimidinas/química , Ratas , Relación Estructura-ActividadRESUMEN
The pharmacokinetic properties of drugs may be altered by kinetic deuterium isotope effects. With specifically deuterated model substrates and drugs metabolized by aldehyde oxidase, we demonstrate how knowledge of the enzyme's reaction mechanism, species differences in the role played by other enzymes in a drug's metabolic clearance, and differences in systemic clearance mechanisms are critically important for the pharmacokinetic application of deuterium isotope effects. Ex vivo methods to project the in vivo outcome using deuterated carbazeran and zoniporide with hepatic systems demonstrate the importance of establishing the extent to which other metabolic enzymes contribute to the metabolic clearance mechanism. Differences in pharmacokinetic outcomes in guinea pig and rat, with the same metabolic clearance mechanism, show how species differences in the systemic clearance mechanism can affect the in vivo outcome. Overall, to gain from the application of deuteration as a strategy to alter drug pharmacokinetics, these studies demonstrate the importance of understanding the systemic clearance mechanism and knowing the identity of the metabolic enzymes involved, the extent to which they contribute to metabolic clearance, and the extent to which metabolism contributes to the systemic clearance.
