Preclinical Bioavailability Assessment of a Poorly Water-Soluble Drug, HGR4113, Using a Stable Isotope Tracer.

Drug solubility limits intravenous dosing for poorly water-soluble medicines, which misrepresents their bioavailability estimation. The current study explored a method using a stable isotope tracer to assess the bioavailability of drugs that are poorly water-soluble. HGR4113 and its deuterated analog, HGR4113-d7, were tested as model drugs. To determine the level of HGR4113 and HGR4113-d7 in rat plasma, a bioanalytical method using LC-MS/MS was developed. The HGR4113-d7 was intravenously administered to rats that were orally pre-administered HGR4113 at different doses; subsequently, the plasma samples were collected. HGR4113 and HGR4113-d7 were simultaneously determined in the plasma samples, and bioavailability was calculated using plasma drug concentration values. The bioavailability of HGR4113 was 53.3% ± 19.5%, 56.9% ± 14.0%, and 67.8% ± 16.7% after oral dosages of 40, 80, and 160 mg/kg, respectively. By eliminating the differences in clearance between intravenous and oral dosages at different levels, acquired data showed that the current method reduced measurement errors in bioavailability when compared to the conventional approach. The present study suggests a prominent method for evaluating the bioavailability of drugs with poor aqueous solubility in preclinical studies.

In Vitro Assessment of CYP-Mediated Drug Interactions for Kinsenoside, an Antihyperlipidemic Candidate.

Kinsenoside, the herb-derived medicine isolated from the plant Anoect chilus, has diverse pharmacological actions, and it is considered to be a promising antihyperlipidemic drug candidate. This study evaluates the effects of kinsenoside on CYP enzyme-mediated drug metabolism in order to predict the potential for kinsenoside-drug interactions. Kinsenoside was tested at different concentrations of 0.1, 0.3, 1, 3, 10, 30, and 100 µM in human liver microsomes. The c Cktail probe assay based on liquid chromatography-tandem mass spectrometry was conducted to measure the CYP inhibitory effect of kinsenoside. Subsequently, the metabolism profiles of amlodipine and lovastatin in human liver microsomes were analyzed following co-incubation with kinsenoside. The concentration levels of the parent drug and the major metabolites were compared with the kinsenoside-cotreated samples. The effect of kinsenoside was negligible on the enzyme activity of all the CYP isozymes tested even though CYP2A6 was slightly inhibited at higher concentrations. The drug-drug interaction assay also showed that the concomitant use of kinsenoside has a non-significant effect on the concentration of lovastatin or amlodipine, and their major metabolites. So, it was concluded that there is almost no risk of drug interaction between kinsenoside and CYP drug substrates via CYP inhibition.

Simultaneous determination of phenolic acids and phthalide compounds by liquid chromatography for quality assessment of Rhizoma cnidii.

This paper describes a simple, rapid, and validated reversed-phase high-performance liquid chromatographic method developed for the determination of 4 major bioactive constituents, namely, chlorogenic acid, ferulic acid, senkyunolide A, and Z-ligustilide in Rhizoma Cnidii extract. A Capcell Pak C18 chromatographic column (150 x 4.6 mm, 3 microm) was used with mobile phases consisting of 0.1% formic acid, acetonitrile, and methanol at a flow rate of 0.8 mL/min and UV detection at 285 nm. Comprehensive validation of the method included evaluation of linearity, repeatability, recovery, and stability. Excellent linear behavior (r2>0.99) was observed over the concentration range of 2-100 microg/mL for the compounds under investigation. Repeatability and accuracy were evaluated by intra- and interday assays; the relative standard deviation (RSD) values were < or = 5.37% and accuracies ranged from 97.1 to 104.9%. Recoveries of the compounds ranged from 94.2 to 104.2% with RSD values of < or = 9.50%. The developed method was successfully applied to the analysis of ethanolic extracts of Rhizoma Cnidii samples. As a result, the concentrations of chlorogenic acid, ferulic acid, Z-ligustilide, and senkyunolide A were determined to be 0.84-5.35, 0.45-1.65, 0.74-4.39, and 0.32-1.14 mg/g herb, respectively. Thus, the developed method was found to be accurate and reproducible and is considered suitable for the qualitative and quantitative analysis of Rhizoma Cnidii for bioactive compounds.