Description

Inflammation

Description

LY315920 (Varespladib) is a potent and selective secretory phospholipase A2 (sPLA) inhibitor with IC50 of 7 nM.

Targets

IC₅₀

In Vitro

LY315920 exhibits the significant inhibitory effect on sPLA2 activity in serum from various species including rat, rabbit, guinea pig and human with IC50 of 8.1 nM, 5.0 nM, 3.2 nM and 6.2 nM, respectively. ^[2] In BAL cells challenged with human sPLA2, LY315920 at doses ranging from 0.1 μM–3 μM reduces the formation of thromboxane mediated by human sPLA2 in a concentration-dependent manner with an IC50 of approximately 0.8 μM. ^[2] In human conjunctival epithelial cell line (HCjE), LY315920 (10 μM) significantly inhibits all-trans-retinoic acid (RA) -induced membrane-associated mucin MUC16 expression by 100% at 24 hours and 99% at 48 hours. ^[3]

In Vivo

Ex vivo, LY315920 at doses ranging from 3 mg/kg to 30 mg/kg via i.v. inhibits human sPLA2-induced release of thromboxane from guinea pig BAL cells with ED50 of 16.1 mg/kg. ^[2] In Transgenic Mice Expressing Human sPLA2, both oral and i.v. administration of LY315920 (0.3 mg/kg–3 mg/kg) abolishes serum sPLA2 activity in a dose and time dependent manner. ^[2]

Clinical Trials

Study on Varespladib Methyl has been completed in Phase II clinical trials in patients with Acute Coronary Syndrome.

Features

LY315920 (Varespladib) is a potent and selective secretory phospholipase A2 inhibitor.

DOC/PC Phospholipase A2 Inhibition Assay

Aliquots of 10 μL of LY315920 solutions in DMSO are added to 20 μL (10 ng) of enzyme in 25 mM Tris.HCl (pH 8) with 0.25 mg/mL BSA and 150 μL of assay buffer containing 50mM Tris (pH 8), 0.2 M NaCl, 2 mM CaCl₂, and 1 mg/mL fatty acid free BSA. To each tube is added 20 μL of a freshly prepared, iced stock solution of the PC and bile salt, which have been sonicated and concocted such that the final 200 μL reaction volume would contain 3 mM DOC/1 mM total PC and approximately 1 × 10⁵ cpm of [¹⁴C]PC. To prepare the lipid substrate, aliquots of labeled PC (1-palmitoyl-2[14C]-oleoylphosphatidyl choline) and 100 mM stock cold PC in chloroform, and 100 mM DOC (sodium salt of deoxycholic acid) in ethanol are mixed, dried under a N2 stream, and then reconstituted in 10 mM Tris with 0.2 mM NaCl, before sonicating for 10 minutes. The assay tubes are incubated for 1 hour in a 40 °C water bath. The reaction is stopped with 1.5 mL of Doles 2-propanol/heptane/0.5 M H₂SO₄ at 40:10:1 (v/v) with 1 mg/mL palmitic acid. The mixtures are then heated for 1 minute at 60 °C before 1 mL of H₂O and 1.25 mL of heptane are added and mixed thoroughly. After the two phases are allowed to separate, the upper phase is transferred to 1 mL of heptane containing 150 mg of dried silica and mixed again before centrifugation for 5 minutes at 1500 g. The supernatant is removed for scintillation counting of the liberated [¹⁴C]oleic acid. The degree of inhibition is compared to diluent controls, and the inhibitory concentrations are calculated.

Animal Models

Transgenic Mice Expressing Human sPLA2 Protein.

Formulation

LY315920 is dissolved in 5% DMSO, 5% ethanol, and 30% polyethylene glycol 300.

Doses

≤3 mg/kg

Administration

Administered via i.v. and p.o.