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Alisporivir is a novel cyclophilin-binding molecule with potent anti-hepatitis C virus (HCV) activity. In vitro data from human liver microsomes suggest that alisporivir is a ...substrate and a time-dependent inhibitor (TDI) of CYP3A4. The aim of the current work was to develop a novel physiologically based pharmacokinetic (PBPK) model to quantitatively assess the magnitude of CYP3A4 mediated drug–drug interactions with alisporivir as the substrate or victim drug. Towards that, a Simcyp PBPK model was developed by integrating in vitro data with in vivo clinical findings to characterize the clinical pharmacokinetics of alisporivir and further assess the magnitude of drug–drug interactions. Incorporated with absorption, distribution, elimination, and TDI data, the model accurately predicted AUC, Cmax, and tmax values after single or multiple doses of alisporivir with a prediction deviation within ±32%. The model predicted an alisporivir AUC increase by 9.4-fold and a decrease by 86% when alisporivir was co-administrated with ketoconazole (CYP3A4 inhibitor) or rifampin (CYP3A4 inducer), respectively. Predictions were within ±20% of the observed changes. In conclusion, the PBPK model successfully predicted the alisporivir PK and the magnitude of drug–drug interactions.
In vitro data suggest that alisporivir is a substrate and inhibitor of CYP3A4 and P-gp. Hence, the potential for drug-drug interactions when alisporivir is co-administered with CYP3A4 and/or P-gp ...inhibitors such as ketoconazole, azithromycin and CYP3A4 inducers such as rifampin were evaluated in three separate clinical studies. Co-administration with ketoconazole (a strong CYP3A4 inhibitor) increased the Cmax , AUC and terminal elimination half-life of alisporivir by approximately two-, eight- ,and threefold, respectively. Co-administration with azithromycin (a putative weak CYP3A4 inhibitor and substrate) had no impact on the Cmax and AUC of alisporivir. Rifampin (a CYP3A4 inducer) caused an approximate 90% reduction in alisporivir Cmax and AUC and a fourfold reduction in alisporivir terminal elimination half-life. Alisporivir as an inhibitor of CYP3A4 caused a 39% increase in azithromycin exposure. The results from these studies establish alisporivir as a sensitive CYP3A4 substrate in vivo. Consequently, co-administered potent CYP3A4 inhibitors and inducers are likely to cause clinically significant changes in the exposure to alisporivir.
For the first time, a liquid chromatographic method with tandem mass spectrometric detection (LC–MS/MS) for the simultaneous determination of ribavirin and rabavirin base was developed and validated ...over the concentration range of 10–5000
ng/ml, respectively, using a 0.025
ml monkey plasma sample. Ribavirin, ribavirin base, and the internal standards were extracted from monkey plasma via protein precipitation. After evaporation of the supernatant, the extract was reconstituted with 5% methanol (containing 0.1% formic acid) and injected onto the LC–MS/MS system. Optimum chromatographic separation was achieved on a Waters Atlantis dc18 (150
mm
×
2.1
mm, 5
μm) column with mobile phase run in gradient with 100% water containing 0.5% formic acid (
A) and 90% acetonitrile (containing 0.5% formic acid (
B). The flow rate was 0.4–0.6
ml/min with total cycle time of approximately 7.0
min. Post-column addition of acetonitrile (containing 0.1% formic acid) at 0.3
ml/min was used to increase the ionization efficiency in the MS source. The method was validated for sensitivity, linearity, reproducibility, stability and recovery. Lack of adverse matrix effect and carry-over was also demonstrated. The intra-day and inter-day precision and accuracy of the quality control (QC) samples were <9.0% relative standard deviation (R.S.D.) and 10.8% bias for ribavirin, and 10.3% R.S.D. and 11.3% bias for ribavirin base. The current specific, accurate and precise assay is useful in support of the toxicokinetic and pharmacokinetic studies of these compounds.
Cyclophilin inhibitors have shown activity against a variety of viruses, including HCV. NIM811, a novel, non-immunosuppressive cyclophilin inhibitor was studied in ascending doses in a randomized, ...double-blind, placebo-controlled 14-day trial in genotype 1 HCV patients. Doses of 10 up to 600
mg were given orally once or twice daily as monotherapy (9:3 randomization of NIM811:placebo). 600
mg or placebo bid for 14 days was then co-administered with pegylated interferon alpha (PEG-IFN-α) administered on days 1 and 8 to genotype 1 relapsers.
NIM811 was well tolerated at all doses. Although lack of antiviral effect was noted in the monotherapy arms, liver transaminase normalization occurred at doses over 75
mg. Mild, clinically non-significant elevations of bilirubin, and significant declines in platelet numbers were observed in the 400 and 600
mg bid groups. In the combination group, the mean HCV RNA decline was 2.85
log, compared to a 0.56
log in the PEG-IFN alone arm. The mean ALT (alanine transaminase) declined significantly by day 14 in the combination, but was unchanged in the PEG-IFN alone group. In the combination therapy group, the mean platelets were 203
×
10
9/L at baseline and fell to 105
×
10
9/L by day 14; for patients treated with PEG-IFN the values were 177
×
10
9/L and 139
×
10
9/L. There was a significant increase in bilirubin, although this did not reach clinically concerning levels. There were no severe or serious adverse events. The pharmacokinetics in both monotherapy and combination arms were dose linear and not affected by PEG-INF.
NIM811 monotherapy resulted in a normalization of liver transaminases in the absence of significant virological response. The combination of NIM811 and pegylated interferon alpha showed significant antiviral activity compared to interferon alone in genotype 1 HCV relapsers. The use of oral cyclophilin inhibitors as part of a combination regime for treatment of hepatitis C, especially to deter resistance, holds promise.
The analysis of pegylated-interferon-a@@d2a@ in patient serum samples is of high interest for clinic research trials, as this therapeutic protein has become an important antiviral treatment. In this ...study, an LC-MS/MS method for the absolute quantification of pegylated-interferon-a@@d2a@ in human serum was developed. The assay achieved a lower limit of quantification of 3.6 ng/mL (60 pM) with the use of a monolithic C@@d18@ solid phase extraction to enrich the target protein. The linear range of the assay was defined up to 54 ng/mL to measure the typical clinical pegylated-interferon-a@@d2a@ levels, and within this range, the precision and accuracy were found to be within +/-20%. The method was applied to a clinical study and found suitable for high-throughput analysis of pegylated-interferon-a@@d2a@ in human serum. In addition, further investigations suggested the enrichment step may have general application to the sensitive analysis of other low molecular weight proteins.
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