Lornoxicam

Quantitative prediction of hepatic clearance is a key element in predicting the human pharmacokinetic profile in the nonclinical stages. In the present study, we focused on the major cytochrome P450 (P450) isoforms (CYP1A2, CYP2C9, CYP2C19, CYP2D6, CYP3A4) and tested a relative activity factor (RAF) method to quantitatively predict in vivo hepatic intrinsic clearance (CL_h,int,vivo) and fraction metabolized (f_m) by the P450 isoforms directly from an in vitro recombinant P450 system. We selected multiple probe substrates for CYP1A2 (caffeine, tizanidine, phenacetin), CYP2C9 ((S)-acenocoumarol, glimepiride, lornoxicam, tolbutamide, (S)-warfarin), CYP2C19 ((S)-lansoprazole, omeprazole, pantoprazole), CYP2D6 (desipramine, metoprolol, nebivolol, tolterodine), and CYP3A4 (alprazolam, felodipine, midazolam, nisoldipine, sildenafil, triazolam) to calculate the representative RAF value for each P450 isoform based on the in vivo-to-in vitro clearance ratio of the multiple probe substrates. The most pronounced substrate dependency of the RAF values was noted for CYP3A4 (2698 [alprazolam] to 19073 [nisoldipine] pmol P450/kg). Using the geometric mean of the RAF values for each isoform, a within 3-fold prediction of the CL_h,int,vivo was obtained for all the 11 test drugs, except glibenclamide, which is a known substrate of hepatic uptake transporters. The f_m values of the responsible P450 isoform(s) could be well predicted for mexiletine, tamsulosin, risperidone, celecoxib, and glibenclamide. This simple, practical RAF method can be one of the useful nonclinical methods to estimate the CL_h,int,vivo and f_m mediated by the major P450 isoforms, which would promote earlier understanding of the impact of genetic polymorphisms and drug-drug interactions on the human pharmacokinetics of the substrate compounds. SIGNIFICANCE STATEMENT: The relative activity factor method has been used for extrapolating in vitro clearance from recombinant systems to liver microsomes, but this study utilized this method to predict in vivo hepatic clearance and fraction metabolized values. By applying relative activity factor values obtained from multiple probe substrates, this study was able to quantitatively predict the in vivo clearances mediated by CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. This simple, practical method will help optimize metabolic clearances via the major cytochrome P450 isoforms in the nonclinical stages.

Lipoxygenase (LOX) and cyclooxygenase (COX) pathways generate biologically active mediators implicated in inflammatory disorders and several classes of cancer. Non-steroidal anti-inflammatory drugs (NSAIDs) inhibit the COX pathway by inhibiting the COX-1 and COX-2 enzymes. We reported earlier that several NSAIDs, including naproxen, aspirin and acetaminophen, inhibited lipoxygenase (LOX) enzyme at sub-micromolar concentrations. In continuation, the present work demonstrates the anti-LOX activity of nine more NSAIDs supported by in vitro, in silico, MD simulation and breast cancer cell line studies. All tested drugs displayed potent to excellent inhibitory profiles with IC₅₀ values <24.93 ± 0.64 μM. Aceclofenac (IC₅₀ 0.85 ± 0.06 μM) was the most active drug, followed by indomethacin (IC₅₀ 1.13 ± 0.07 μM), meloxicam (IC₅₀ 1.94 ± 0.07 μM) and ketorolac (IC₅₀ 9.26 ± 0.82 μM). Celecoxib (IC₅₀ 15.81 ± 0.71 μM), lornoxicam (IC₅₀ 16.54 ± 0.28 μM) and nimesulide (IC₅₀ 19.87 ± 0.85 μM) showed excellent inhibitory profiles. Flurbiprofen (IC₅₀ 21.73 ± 0.93 μM) and etoricoxib (IC₅₀ 24.93 ± 0.64 μM) moderately inhibited the target enzyme. SAR studies revealed that active molecules decorated with the carboxylate group afforded strong binding interactions as observed by in vitro assays and structural features. Other drugs, including enol derivatives and celecoxib, also showcased enhanced binding interactions. However, the cytotoxic effects of NSAIDs against the MCF-7 breast cancer cell line did not disclose significant anticancer activity. Molecular docking studies against human 5-LOX offered the best binding affinities for aceclofenac (-13.54 kcal/mol), accompanied by conventional hydrogen bonding and hydrophobic interactions as supported by the in vitro results. Docking studies with DNA dodecamer established minor groove binding with their possible role in DNA replication and gene expression. Density functional theory (DFT) and ESP studies, MD simulations and MMPBSA free energy calculations further reiterated the stability of ligand-receptor complexes. Overall, these findings highlight the potential of targeted NSAIDs as dual COX/LOX inhibitors with broader therapeutic relevance in inflammatory disorders.