DISPOSITION AND PHARMACOKINETICS OF THE ANTIMIGRAINE DRUG, RIZATRIPTAN, IN HUMANS

This paper is available online at http://www.dmd.org ABSTRACT: The The primary route of rizatriptan elimination occurred via nonrenal route(s) (i.e., metabolism) because the CL r of rizatriptan accounted for 25% of total CL. Furthermore, the CL r was higher than normal glomerular filtration rate (ϳ130 ml/min), indicating that this compound was actively secreted by renal tubules. The absorption of rizatriptan was approximately 90%, but it experienced a moderate first-pass effect, resulting in a bioavailability estimate of 47%

Statistical learning of peptide retention behavior in chromatographic separations: a new kernel-based approach for computational proteomics

<p>Abstract</p> <p>Background</p> <p>High-throughput peptide and protein identification technologies have benefited tremendously from strategies based on tandem mass spectrometry (MS/MS) in combination with database searching algorithms. A major problem with existing methods lies within the significant number of false positive and false negative annotations. So far, standard algorithms for protein identification do not use the information gained from separation processes usually involved in peptide analysis, such as retention time information, which are readily available from chromatographic separation of the sample. Identification can thus be improved by comparing measured retention times to predicted retention times. Current prediction models are derived from a set of measured test analytes but they usually require large amounts of training data.</p> <p>Results</p> <p>We introduce a new kernel function which can be applied in combination with support vector machines to a wide range of computational proteomics problems. We show the performance of this new approach by applying it to the prediction of peptide adsorption/elution behavior in strong anion-exchange solid-phase extraction (SAX-SPE) and ion-pair reversed-phase high-performance liquid chromatography (IP-RP-HPLC). Furthermore, the predicted retention times are used to improve spectrum identifications by a <it>p</it>-value-based filtering approach. The approach was tested on a number of different datasets and shows excellent performance while requiring only very small training sets (about 40 peptides instead of thousands). Using the retention time predictor in our retention time filter improves the fraction of correctly identified peptide mass spectra significantly.</p> <p>Conclusion</p> <p>The proposed kernel function is well-suited for the prediction of chromatographic separation in computational proteomics and requires only a limited amount of training data. The performance of this new method is demonstrated by applying it to peptide retention time prediction in IP-RP-HPLC and prediction of peptide sample fractionation in SAX-SPE. Finally, we incorporate the predicted chromatographic behavior in a <it>p</it>-value based filter to improve peptide identifications based on liquid chromatography-tandem mass spectrometry.</p

THE ABSORPTION, DISTRIBUTION, METABOLISM AND EXCRETION OF ROFECOXIB, A POTENT AND SELECTIVE CYCLOOXYGENASE-2 INHIBITOR, IN RATS AND DOGS

This paper is available online at http://www.dmd.org ABSTRACT: Absorption, distribution, metabolism, and excretion studies were conducted in rats and dogs with rofecoxib (VIOXX, MK-0966), a potent and highly selective inhibitor of cyclooxygenase-2 (COX-2). In rats, the nonexponential decay during the terminal phase (4-to 10-h time interval) of rofecoxib plasma concentration versus time curves after i.v. or oral administration of

Partial protection against multiple rt-shiv162p3 vaginal challenge of rhesus macaques by a silicone elastomer vaginal ring releasing the nnrti mc1220

OBJECTIVES: The non-nucleoside reverse transcriptase inhibitor MC1220 has potent in vitro activity against HIV type 1 (HIV-1). A liposome gel formulation of MC1220 has previously been reported to partially protect rhesus macaques against vaginal challenge with a simian HIV (SHIV). Here, we describe the pre-clinical development of an MC1220-releasing silicone elastomer vaginal ring (SEVR), including pharmacokinetic (PK) and efficacy studies in macaques. METHODS: In vitro release studies were conducted on SEVRs loaded with 400 mg of MC1220, using simulated vaginal fluid (SVF, n = 4) and 1 : 1 isopropanol/water (IPA/H(2)O, n = 4) as release media. For PK evaluation, SEVRs were inserted into adult female macaques (n = 6) for 30 days. Following a 1week washout period, fresh rings were placed in the same animals, which were then challenged vaginally with RT-SHIV162P3 once weekly for 4 weeks. RESULTS: SEVRs released 1.66 and 101 mg of MC1220 into SVF and IPA/H(2)O, respectively, over 30 days, the differential reflecting the low aqueous solubility of the drug. In macaque PK studies, MC1220 was consistently detected in vaginal fluid (peak 845 ng/mL) and plasma (peak 0.91 ng/mL). Kaplan–Meier analysis over 9weeks showed significantly lower infection rates for animals given MC1220-containing SEVRs than placebo rings (hazard ratio 0.20, P = 0.0037). CONCLUSIONS: An MC1220-releasing SEVR partially protected macaques from vaginal challenge. Such ring devices are a practical method for providing sustained, coitally independent protection against vaginal exposure to HIV-1

Sustained Release of the CCR5 Inhibitors CMPD167 and Maraviroc from Vaginal Rings in Rhesus Macaques

Antiretroviral entry inhibitors are now being considered as vaginally administered microbicide candidates for the prevention of the sexual transmission of human immunodeficiency virus. Previous studies testing the entry inhibitors maraviroc and CMPD167 in aqueous gel formulations showed efficacy in the macaque challenge model, although protection was highly dependent on the time period between initial gel application and subsequent challenge. In this paper, we describe the sustained release of maraviroc and CMPD167 from matrix-type silicone elastomer vaginal rings both in vitro and in vivo. Both inhibitors were released continuously during 28 days from rings in vitro at rates of 100 to 2,500 μg/day. In 28-day pharmacokinetic studies in rhesus macaques, the compounds were measured in the vaginal fluid and vaginal tissue; steady-state fluid concentrations were ∼10(6)-fold greater than the 50% inhibitory concentrations (IC(50)s) for simian human immunodeficiency virus 162P3 inhibition in macaque lymphocytes in vitro. Plasma concentrations for both compounds were very low. The pretreatment of macaques with Depo-Provera (DP), which is commonly used in macaque challenge studies, was shown to significantly modify the biodistribution of the inhibitors but not the overall amount released. Vaginal fluid and tissue concentrations were significantly decreased while plasma levels increased with DP pretreatment. These observations have implications for designing macaque challenge experiments and also for ring performance during the human female menstrual cycle