Chemical engineers ensure the efficiency and safety of chemical processes, adapt the chemical make-up of products to meet environmental or economic needs, and apply new technologies to improve existing processes.”, Quality Control of (2E,4E)-Hepta-2,4-dienal.
Two investigational compounds (FRM-1, (R)-7-fluoro-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide and FRM-2, (R)-7-cyano-N-(quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide) resided in rat brain longer than in systemic circulation. In Caco-2 directional transport studies, they both showed good intrinsic passive permeability but differed significantly in efflux susceptibility (efflux ratio of <2 and similar to 7, respectively), largely attributed to P-glycoprotein (P-gp). Capitalizing on these interesting properties, we investigated how cerebrospinal fluid (CSF) concentration (C-CSF) would be shaped by unbound plasma concentration (C-u,C-p) and unbound brain concentration (C-u,C-b) in disequilibrium conditions and at steady state. Following subcutaneous administration, FRM-1 C-CSF largely followed C-u,C-p initially and leveled between C-u,C-p and C-u,C-b. However, it gradually approached C-u,C-b and became lower than, but parallel to C-u,C-b at the terminal phase. In contrast, FRM-2 C-CSF temporal profile mostly paralleled the C-u,C-p but was at a much lower level. Upon intravenous infusion to steady state, FRM-1 C-CSF and C-u,C-b were similar, accounting for 61% and 69% of the Cu, indicating a case of largely passive diffusion-governed brain penetration where C-CSF served as a good surrogate for C-u,C-b. On the contrary, FRM-2 C-CSF and C-u,C-b were remarkably lower than C-u,C-p, (17% and 8% of C-u,C-p respectively), suggesting that FRM-2 brain penetration was severely impaired by P-gp-mediated efflux and C-CSF underestimated this impact. A semi-physiologically based pharmacokinetic (PBPK) model was constructed that adequately described the temporal profiles of the compounds in the plasma, brain and CSF. Our work provided some insight into the relative importance of blood-brain barrier (BBB) and blood-CSF barrier (BCSFB) in modulating CCSF. (C) 2014 Elsevier Inc. All rights reserved. Each elementary reaction can be described in terms of its molecularity, the number of molecules that collide in that step. The slowest step in a reaction mechanism is the rate-determining step.Interested yet? Keep reading other articles of 4313-03-5, you can contact me at any time and look forward to more communication. Quality Control of (2E,4E)-Hepta-2,4-dienal.
Reference:
Quinuclidine – Wikipedia,
,Quinuclidine | C7H13N | ChemSpider