Discovery of potent, selective, and orally active carboxylic acid based inhibitors of matrix metalloproteinase-13.

The matrix metalloproteinase enzyme MMP-13 plays a key role in the degradation of type II collagen in cartilage and bone in osteoarthritis (OA). An effective MMP-13 inhibitor would therefore be a novel disease modifying therapy for the treatment of arthritis. Our efforts have resulted in the discovery of a series of carboxylic acid inhibitors of MMP-13 that do not significantly inhibit the related MMP-1 (collagenase-1) or tumor necrosis factor-alpha (TNF-alpha) converting enzyme (TACE). It has previously been suggested (but not proven) that inhibition of the latter two enzymes could lead to side effects. A promising carboxylic acid lead 9 was identified and a convergent synthesis developed. This paper describes the optimization of 9 and the identification of a compound 24f for further development. Compound 24f is a subnanomolar inhibitor of MMP-13 (IC(50) value 0.5 nM and K(i) of 0.19 nM) having no activity against MMP-1 or TACE (IC(50) of >10000 nM). Furthermore, in a rat model of MMP-13-induced cartilage degradation, 24f significantly reduced proteoglycan release following oral dosing at 30 mg/kg (75% inhibition, p < 0.05) and at 10 mg/kg (40% inhibition, p < 0.05).

Strategy for identification of leachables in packaged pharmaceutical liquid formulations.

Drug stability is one of the key properties to be monitored in pharmaceutical drug development. Drug degradation products, impurities and/or leachables from the drug product and packages may have significant impacts on drug efficacy, safety profile and storage conditions. In the registration stability samples of an ophthalmic pharmaceutical drug product, an unknown compound was found at a level of 0.19% by HPLC analysis. Subsequent liquid chromatography/mass spectrometry (LC/MS) analysis with electrospray ionization (ESI) indicated that the unknown was not related to the drug substance and was most likely a leachable. Identification of this unknown leachable was needed to evaluate the impact on drug safety. Through systematic extraction of various components or component combination of the packaging materials, and subsequently LC/MS analysis, the unknown was found to be a leachable coming from the varnish applied to the label. In general, using LC/MS alone is not sufficient to elucidate the structure of a complete unknown. Gas chromatography/mass spectrometry (GC/MS) was then conducted with a chemical ionization (CI) source to determine the retention time and mass of the compound of interest. Both CI and ESI sources generated the same protonated molecular ion [M+H] and similar fragmentation ions, which provides a good correlation of the unknown eluted in the liquid chromatogram and in the gas chromatogram. GC/MS with electron impact (EI) was then conducted to obtain the EI mass spectrum of this unknown. It was identified as monomethyl derivative of mephenesin through the NIST library search. The identification strategy utilized electrospray LC/MS and GC/MS with chemical and electron ionization sources which provided complimentary information for structure elucidation of this unknown compound. This combination approach in conjunction with systematic extraction was necessary for the determination of the source of this unknown in the pharmaceutical drug stability studies.

Optimization of halopemide for phospholipase D2 inhibition.

Halopemide, which was identified by HTS to inhibit phospholipase D2 (PLD2), provided the basis for an exploratory effort to identify potent inhibitors of PLD2 for use as inflammatory mediators. Parallel synthesis and purification were utilized to rapidly identify orally available amide analogs derived from indole 2-carboxylic acids with superior potency versus PLD2.

Preclinical pharmacology of lumiracoxib: a novel selective inhibitor of cyclooxygenase-2.

1. This manuscript presents the preclinical profile of lumiracoxib, a novel cyclooxygenase-2 (COX-2) selective inhibitor. 2. Lumiracoxib inhibited purified COX-1 and COX-2 with K(i) values of 3 and 0.06 microM, respectively. In cellular assays, lumiracoxib had an IC(50) of 0.14 microM in COX-2-expressing dermal fibroblasts, but caused no inhibition of COX-1 at concentrations up to 30 microM (HEK 293 cells transfected with human COX-1). 3. In a human whole blood assay, IC(50) values for lumiracoxib were 0.13 microM for COX-2 and 67 microM for COX-1 (COX-1/COX-2 selectivity ratio 515). 4. Lumiracoxib was rapidly absorbed following oral administration in rats with peak plasma levels being reached between 0.5 and 1 h. 5. Ex vivo, lumiracoxib inhibited COX-1-derived thromboxane B(2) (TxB(2)) generation with an ID(50) of 33 mg kg(-1), whereas COX-2-derived production of prostaglandin E(2) (PGE(2)) in the lipopolysaccharide-stimulated rat air pouch was inhibited with an ID(50) value of 0.24 mg kg(-1). 6. Efficacy of lumiracoxib in rat models of hyperalgesia, oedema, pyresis and arthritis was dose-dependent and similar to diclofenac. However, consistent with its low COX-1 inhibitory activity, lumiracoxib at a dose of 100 mg kg(-1) orally caused no ulcers and was significantly less ulcerogenic than diclofenac (P<0.05). 7. Lumiracoxib is a highly selective COX-2 inhibitor with anti-inflammatory, analgesic and antipyretic activities comparable with diclofenac, the reference NSAID, but with much improved gastrointestinal safety.

N-arylaminonitriles as bioavailable peptidomimetic inhibitors of cathepsin B.

To improve the pharmacokinetics of a previously reported series of dipeptidyl nitrile cathepsin B inhibitors, the P(2)-P(3) amide group was replaced with an arylamine. Further optimization of this template resulted in highly potent and selective inhibitors with excellent oral availability.