ABSTRACT
Small interference RNA (siRNA) is a class of short double-stranded RNA molecules that cause mRNA degradation through an RNA interference mechanism and is a promising therapeutic modality. RBD1016 is a siRNA drug in clinical development for the treatment of chronic Hepatitis B Virus (HBV) infection, which contains a conjugated with N-acetylglucosamine moiety that can facilitate its hepatic delivery. We aimed to construct a semi-mechanistic model of RBD1016 in pre-clinical animals, to elucidate the pharmacokinetic/pharmacodynamic (PK/PD) profiles in mice and PK profiles in monkeys, which can lay the foundation for potential future translation of RBD1016 PK and PD from the pre-clinical stage to the clinic stage. The proposed semi-mechanistic PK/PD model fitted PK and PD data in HBV transgenic mice well and described plasma and liver concentrations in the monkeys well. The simulation results showed that our model has a reasonable predictive ability for Hepatitis B surface antigen (HBsAg) levels after multiple dosing in mice. Further PK and PD data for RBD1016, including clinical data, will assist in refining the model presented here. Our current effort focused on model building for RBD1016, we anticipate that the model could apply to other GalNAc-siRNA drugs.
ABSTRACT
A selective and reproducible HPLC-MS/MS method was developed and fully validated for the determination of cefbuperazone in human plasma and urine. Samples were prepared using protein precipitation and separated on a Zorbax Eclipse Plus C18 column (2.1×50mm, 3.5µm). The API-4000 mass spectrometer was operated under multiple reaction monitoring mode (MRM) using the electrospray ionization technique. Linearity was achieved from 0.250 to 250µg/mL in plasma and 20.0-5000µg/mL in urine. The method was successfully applied to a pharmacokinetic study of cefbuperazone in healthy Chinese volunteers after drip intravenous infusion of 0.5, 1.0, 2.0g cefbuperazone sodium injection. Cefbuperazone reached a maximum concentration (Cmax) of 44.7±8.1µg/mL, 86.7±12.7µg/mL and 168±14µg/mL in 0.5, 1.0 and 2.0g dose groups respectively, at 60min after the start of infusion. The half-life (t1/2) was between 1.8-1.9h, and the elimination constant (kel) was between 0.36-0.39h(-1). The results proved that cefbuperazone showed linear pharmacokinetic profile in the dose range of 0.5-2.0g without gender difference. Drug accumulation was not observed. Cefbuperazone reached the maximum excretion rate in urine 2h after the start of infusion. About 60.0% of the administered drug was excreted via urine as unchanged form within 12h. The cumulative excretion of cefbuperazone after single drip intravenous infusion was proportional to the administered dose within the range from 0.5g to 2.0g.
