Jaume Pascual

Structure-based design of cyclooxygenase-2 selectivity into ketoprofen.

We have recently described how to achieve COX-2 selectivity from the non-selective inhibitor indomethacin (1) using a combination of a pharmacophore and computer 3-D models based on the known X-ray crystal structures of cyclooxygenases. In the present study we have focused on the design of COX-2 selective analogues of the NSAID ketoprofen (2). The design is similarly based on the combined use of the previous pharmacophore together with traditional medicinal chemistry techniques motivated by the comparative modeling of the 3-D structures of 2 docked into the COX active sites. The analysis includes use of the program GRID to detect isoenzyme differences near the active site region and is aimed at suggesting modifications of the basic benzophenone frame of the lead compound 2. The resulting series of compounds bearing this central framework is exemplified by the potent and selective COX-2 inhibitor 17 (LM-1669).

Stereoselective metabolic pathways of ketoprofen in the rat: Incorporation into triacylglycerols and enantiomeric inversion

The enantiomeric bioinversion of ketoprofen (KP) enantiomers and their incorporation into triacylglycerols were investigated in the rat (1) in vitro, using liver homogenates, subcellular fractions, and hepatocytes, and (2) in vivo, in different tissue samples after oral administration of the radiolabelled compounds. In liver homogenates or subcellular fractions, the enantiomer (S)-ketoprofen (S-KP) was recovered unchanged, whereas (R)-ketoprofen (R-KP) was partially converted into its Coenzyme A (CoA) thioester and inverted to S-KP. Both processes occurred mainly in the mitochondrial fraction. This supports the mechanism of inversion via stereoselective formation of CoA thioester of R-KP, already described for other non-steroidal anti-inflammatory drugs. Incorporation into triacylglycerols was detected after incubation with intact hepatocytes in the presence of added glycerol. The process was stereoselective for R-KP vs. S-KP (covalently bound radioactivity 26,742 +/- 4,665 dpm/10(6) cells vs. 6,644 +/- 3,179 dpm/10(6) cells, respectively). However, no incorporation was found in liver samples after oral administration of either R-KP or S-KP. On the contrary, in adipose tissue samples a significant and stereoselective formation of hybrid triacylglycerols was observed: 11,076 +/- 2,790 dpm.g-1 for R-KP vs. 660 +/- 268 dpm.g-1 for S-KP. The incorporated R/S ratio, higher in adipose tissue (R/S = 17) than in hepatocytes (R/S = 4), indicates that fat may be the main tissue store for the xenobiotic R-KP in rats.

Stereoselective synthesis of both enantiomers of ketoconazole from (R)- and (S)-epichlorohydrin

Abstract Stereoselective syntheses of both enantiomers of ketoconazole (1) from commercially available (R)- or (S)-epichlorohydrin has been developed. The key-step of these syntheses involves the selective substitution of the methylene chlorine atom by benzoate on a mixture of (2S,4R)- 14a and (2R,4R)- 15a or of their enantiomers, followed by crystallization of the corresponding cis-benzoates, (2S,4R)- 18 or (2S,4S)- 18 , from which (+)- or (−)-1 were obtained as described for (±)-1. The ees of (+)- and (−)-ketoconazole were determined by HPLC on the CSP Chiralcel OD-H.

Synthesis and pharmacological evaluation of new cysLT1 receptor antagonists

Summary This paper describes the synthesis and pharmacological evaluation of three series of compounds 4a–b , 13a–k and 19 , structurally related to the known potent cysLT 1 receptor antagonists RG-12553, ICI-204219 and ONO-1078 , respectively. The common structural feature of these new series is the presence of a 4-quinolone nucleus acting as a template for substitution of the aromatic nucleus present in the prototype antagonists. We describe the evolution of these series leading to antagonists with potency at nanomolar concentrations in vitro.

Randomized, Crossover and Single-Dose Bioquivalence Study of Two Oral Desogestrel Formulations (Film-Coated Tablets of 75 μg) in Healthy Female Volunteers

Despite the increase in the substitution of branded medicinal product with generic drugs, this is a controversial issue for some pharmacological groups (such as contraceptives). The aim of the present clinical trial was to assess the bioequivalence and tolerability of two oral formulations of desogestrel. Thirty-three healthy female volunteers participated in this randomized and two-way crossover study. During two separate experimental periods, with at least four weeks of washout period, women received a single oral dose of 75 μg of desogestrel from each of the formulations (test formulation and reference formulation). Desogestrel bioavailability was determined by the measurement of 3-ketodesogestrel plasma concentration. Pharmacokinetic parameters were comparable and the 90% CI for the ratio of Cmax (96.14–114.53%) and AUC0–t (105.73–123.83%) values for the test and reference formulations fell within the established regulatory interval (80–125%). Both formulations were also comparable in terms of tolerability. From the results of this study it can be concluded that test formulation (desogestrel 75 μg, Cyndea PHARMA S.L.) is bioequivalent to the reference formulation (Cerazet® 75 μg, Organon Española S.A.).

Pharmacological profile of MEN91507, a new CysLT1 receptor antagonist

MEN91507 (8-[2-(E)-[4-[4-(4-fluorophenyl)butyloxy]phenyl]vinyl]-4-oxo-2-(5-1H-tetrazolyl)-4H-1-benzopyran sodium salt)) potently displaced [3H]leukotriene D(4) binding from guinea-pig lung and dimethylsulphoxide-differentiated U937 (dU937) cell membranes (K(i) 0.50 +/- 0.16 and 0.65 +/- 0.29 nM, respectively). On the other hand, MEN91507 did not display significant binding affinity for a series of receptors or channels. In functional studies on dU937 cells, MEN91507 behaved as insurmountable antagonist of leukotriene D(4)-induced calcium transients, with an apparent pK(B) of 10.25 +/- 0.15. In anaesthetized guinea-pigs, MEN91507 antagonized in a dose-dependent manner leukotriene D(4)-induced bronchoconstriction following i.v. or oral administration: the ED(50s) were 3.0 +/- 0.3 and 140 +/- 90 nmol/kg, respectively. The inhibition of leukotriene D(4)-induced bronchoconstriction by MEN91507 was long-lasting, since a dose of 0.6 micromol/kg produced 74% reduction of the response after 8 h from administration. Likewise, leukotriene D(4)-induced microvascular leakage was antagonized by MEN91507 either following i.v. or oral administration: a significant inhibitory effect was still evident at 16 h from oral administration of a dose of 6 micromol/kg. It is concluded that MEN91507 is a potent and selective antagonist of both guinea-pig and human CysLT(1) receptors; in addition, in vivo studies on guinea-pigs indicate that MEN91507 is an orally available and long-lasting antagonist of the bronchomotor and pro-inflammatory effects induced by leukotriene D(4) through the stimulation of CysLT(1) receptors.

Synthesis and pharmacological evaluation of new4-[2-(7-heterocyclemethoxynaftalen-2-ylmethoxy)ethyl]benzoic acidsas LTD4-antagonists

Abstract A group of new 4-[2-(7-heterocyclemethoxynaftalen-2-ylmethoxy)ethyl]benzoic acids have been synthesized and pharmacologically evaluated as LTD 4 -antagonists. Thiazole derivatives, especially 4-[2-[7-(4-cyclobutylthiazole-2-ylmethoxyl)naphthalen-2-ylmetho-xy]ethyl]benzoic acid, present considerable activity and improved pharmacokinetic profiles in comparison with our quinoline containing lead molecule confirming the interest of our compounds as potentially oral antiasthmatics and that the 4-alkylthiazole system can be considered as bioisosteric of the quinoline ring at least in our series of compounds.