Avasimibe

Avasimibe at concentration of 1μg/mL causes reduction of Total cholesterol (TC) and Esterified cholesterol (EC) through inhibiting LDL binding and decreasing scavenger receptor numbers during foam cell formation in human monocyte-derived macrophages (HMMs). Avasimibe at concentration of 2μg/mL enhances cholesterol efflux from established HMM foam cells preincubating with 10μg/ml LDL. ^[1] Avasimibe inhibits Lipoprotein(a) accumulation in the culture media of primary monkey hepatocyte in a dose-dependent manner with 11.9% -31.3% inhibition, the change is mainly associated with decreased ApoA. ^[2] Avasimibe incubating at concentration of 10 nM, 1 μM, and 10 μM for 24 hours in HepG2 cells reduce ApoB secretion into media by 25%, 27%, and 43%, respectively. Avasimibe decreases ApoB secretion by enhanced intracellular degradation of ApoB rather than decreased synthesis of ApoB. ^[3] Avasimibe inhibits ACTC with IC50 of 3.3 μM in IC-21 macrophages with consideration of the total inhibitor concentration in the assay sample. ^[4] Avasimibe inhibits human P450 isoenzymes CYP2C9, CYP1A2 and CYP2C19 with IC50 of 2.9 μM, 13.9 μM and 26.5 μM, respectively. ^[5] Avasimibe inhibits ACAT-1 expression and cholesterol ester synthesis in glioma cell lines. Avasimibe inhibits the growth of the glioma cells by inducing cell cycle arrest and apoptosis due to caspase-8 and caspase-3 activation. ^[6]

Avasimibe significantly reduces Lipoprotein(a) and total cholesterol levels in nine healthy male monkeys with a normal chow diet orally treated with CI-1011 at 30 mg/kg per day for 3 weeks, Lipoprotein(a) and total cholesterol levels reduce to 68 and 73% of control levels, respectively. Avasimibe decreases total cholesterol mainly due to reduction of low density lipoprotein (LDL). ^[2] Avasimibe decreases amyloid plaque load in the cortex and hippocampus and reduces the levels of insoluble Abeta40 and Abeta42 and C-terminal fragments of amyloid precursor protein (APP) in brain extracts in young human APP transgenic mice. Avasimibe reduces diffuse amyloid plaques by suppression of astrogliosis and enhanced microglial activation in aged human APP transgenic mice. ^[7]

• P450 Inhibition Studies

  Pooled human liver microsomes (HLM) from at least 15 donors are used for all inhibition assays. For IC50 determinations, the substrate probes are used at their approximate in vitro Km values. All incubations are performed with 100 mM potassium phosphate buffer (pH 7.4) and 1 mM NADPH. For CYP1A2 inhibition study, incubations are performed in a total volume of 0.5 ml, in duplicates with 0.1 mg/ml HLM, 30 μM phenacetin, 1 mM NADPH, and in the presence of avasimibe (0, 0.3, 0.75, 1.5, 3, 7.5, 15, 30, and 40 μM in 50 mM) in a potassium phosphate buffer at pH 7.4. After preincubation at 37 °C for 7 min, NADPH is added to initiate the enzyme reaction. The reaction mixture is quenched with 500 μl of ice-cold 100 ng/ml paracetamol-D₄/CH₃CN after 25 min. The standards (4-acetamidophenol, singlet) and quality controls (triplicates for low, medium, and high) are prepared at room temperature. After mixing, 0.2 ml of the samples is transferred to another plate and submitted for LC/MS/MS analysis after centrifugation at 3000 rpm for 10 min. A Supelco Discovery Amide C16, 100 × 2.1 mm (5-μm particle size) column (Supelco, Bellefonte, PA) is used. The mobile phase is isocratic, 40:60 [acetonitrile/formic acid, 0.1% (v/v)] at 0.2 ml/min.

• Cell lines

  primary human monocyte-derived macrophages

• Concentrations

  1 μg/mL or 2 μg/mL

• Incubation Time

  48 hours

• Method

  For foam cell formation, the growth medium (RPMI medium containing 10% human serum) is aspirated and the BMMs are rinsed four times with RPMI medium, and then HMMs are exposed to RPMI medium containing bovine serum albumin (BSA, 0.2%) and (DMSO, 0.2%, vehicle for CI-1011) (control medium) with and without agacLDL (100 μg protein/ml) and CI-1011 (1 μg/ml) for 48 hours. For cholesterol efflux experiments, HMMs are preincubated with ag-acLDL (100 μg protein/ml) for 24h, and then exposed to control RPMI medium with and without HDL (100 μg protein/ml), CI-1011 (2 μg/ml) or HDL plus CI-1011 (2 μg/ml) for 24–48 hours. Additionally, the appearance of [¹⁴C]FC in the medium is monitored by first preincubating HMMs with RPMI medium containing ag-acLDL (100 μg protein/ml) radiolabeled with [4-¹⁴C]FC (0.5 μCi/ml) in an ethanolic spritz (final concentration, 0.1%) for 24 h. The medium is removed, cells rinsed three times with RPMI medium, and then cells are exposed to control RPMI medium with and without CI-1011 (1–10 μg/ml) for 4–48 h. At each time point, the medium is aspirated and centrifuged to pellet nonadherent cells. The appearance of [¹⁴C]FC in the medium is measured by liquid scintillation spectroscopy. Cellular lipids are extracted using hexane:isopropanol (3:2, v/v) for 1 h. The distribution of cellular radiolabeled cholesterol is measured by subjecting an aliquot of the cell extract and FC and EC standards to thin layer chromatography using petroleum ether:hexane:glacial acetic acid solvent system (85:15:2, v/v). The percent FC efflux is calculated as: medium [¹⁴C]FC dpm/ cell [¹⁴C] dpm×100. FC and TC mass are quantified by gas liquid chromatography using stigmasterol (1 mg/ml) as an internal standard. EC mass is calculated as the difference between TC and FC, and all values are normalized to cell protein. The MBC is defined as the lowest concentration that exhibited 99.9% or more reduction of the numbers of colonies compared with the cfu in the initial inoculum.

• Animal Models

  male cynomolgus monkeys

• Dosages

  30 mg/kg

• Administration

  Orally at a single dose per day for 3 weeks