Clinical Investigation on Endogenous Biomarkers to Predict Strong OAT-Mediated Drug-Drug Interactions.

Background: Endogenous biomarkers are promising tools to assess transporter-mediated drug-drug interactions early in humans.

Methods: We evaluated on a common and validated in vitro system the selectivity of 4-pyridoxic acid (PDA), homovanillic acid (HVA), glycochenodeoxycholate-3-sulphate (GCDCA-S) and taurine towards different renal transporters, including multidrug resistance-associated protein, and assessed the in vivo biomarker sensitivity towards the strong organic anion transporter (OAT) inhibitor probenecid at 500 mg every 6 h to reach close to complete OAT inhibition.

Results: PDA and HVA were substrates of the OAT1/2/3, OAT4 (PDA only) and multidrug resistance-associated protein 4; GCDCA-S was more selective, having affinity only towards OAT3 and multidrug resistance-associated protein 2.

Simultaneous measurement of metabolic stability and metabolite identification of 7-methoxymethylthiazolo[3,2-a]pyrimidin-5-one derivatives in human liver microsomes using liquid chromatography/ion-trap mass spectrometry.

A liquid chromatography/mass spectrometry (LC/MS) method using an atmospheric pressure chemical ionisation source was used to measure the metabolic stability and metabolite identification of 7-methoxymethylthiazolo[3,2-a]pyrimidin-5-one derivative (1) in human liver microsomes. After 15 min incubation with human liver microsomes, compound 1 exhibited metabolic turnover of 44%. Data-dependent tandem mass spectrometry (MS/MS) scanning was used to generate product ion spectra from the protonated ions of the compound and its metabolites.

The use of liquid chromatography-atmospheric pressure chemical ionization mass spectrometry to explore the in vitro metabolism of cyanoalkyl piperidine derivatives.

A LC/MS method using atmospheric pressure chemical ionization, positive ion mode and full scan to measure the in vitro metabolic stability of cyanoalkyl functionalized compounds with the human liver microsomes was employed. Percentage metabolism examined for the five cyanoalkyl piperidines revealed the optimal chain length and positioning of these functions to produce the most metabolically stable compound. The 4-cyanomethyl piperidine derivative was the most stable compound with 15% metabolism after 15 min incubation with human liver microsomes.

Simultaneous measurement of drug metabolic stability and identification of metabolites using ion-trap mass spectrometry.

The use of in vitro drug metabolism data in the understanding of in vivo pharmacokinetic, safety and toxicity data has become a large area of scientific interest. This has stemmed from a trend in the pharmaceutical industry to use in vitro data generated from human tissue as a criterion to select compounds for further investigation. As well as measuring metabolic stability in vitro using human liver microsomal preparations, the identification of possible metabolite(s) formed may play a vital role in Hit-to-Lead and Lead optimisation processes.

Enovin, a member of the glial cell-line-derived neurotrophic factor (GDNF) family with growth promoting activity on neuronal cells. Existence and tissue-specific expression of different splice variants.

Glial cell-line-derived neurotrophic factor (GDNF), neurturin and persephin are neurotrophic factors involved in neuroneal differentiation, development and maintenance. They act on different types of neuroneal cells and signal through a receptor complex composed of a specific ligand-binding subunit of the GDNF family receptor alpha (GFRalpha) family together with a common signaling partner, the cRET protein tyrosine kinase. We describe the molecular cloning, expression, chromosomal localization and functional characterization of enovin, a fourth GDNF family member almost identical to the recently described artemin.

Molecular cloning, expression and characterization of the human serine/threonine kinase Akt-3.

Akt (also known as PKB or RAC-PK) is an intracellular serine/threonine kinase involved in regulating cell survival. Although this makes it a promising target for the discovery of drugs to treat human cancer, a complicating factor may be the role played by Akt in insulin signalling. Two human isoforms, Akt-1 and Akt-2, have been described previously and a third isoform has been identified in rats (here termed Akt-3, but also called RAC-PK-gamma or PKB-gamma).