Ticagrelor

Ticagrelor is an active drug which, does not require metabolic activation after intestinal absorption. It does not compete directly with ADP at the ADP binding site but occupies an adjacent binding site and acts in an allosteric way, resulting in a reversible conformational change of the receptor. Ticagrelor binds reversibly to the receptor and exhibits rapid onset and offset of effect. Binding studies in rh-P2Y12 receptor-transfected CHO-K1 cells indicate that ticagrelor exhibits potent, rapid, and reversible binding, with a K_d of 10.5 nM, a k_on (association constant) of 0.00011/(nM•s), a k_off (dissociation constant) of 0.00087/s, and half-life values of 4 min for binding and 14 min for unbinding, indicating that the magnitude of platelet inhibition is dependent on concentrations of drug available to bind platelets. ^[1]

Ticagrelor moderately inhibits CYP2C9 activity in human liver microsomes, while exhibiting little or no inhibition of CYP1A2, CYP2B6, CYP2C8, CYP2C19, CYP2D6, and CYP2E1. In human liver microsomes, ticagrelor inhibits midazolam 4-hydroxylation, while activating 1_-hydroxylation of midazolam. Evaluated in fresh human hepatocytes, ticagrelor is not an inducer of CYP1A2 or CYP3A4. ^[3]

Absorption of ticagrelor is rapid with t _max of 1.3-2 h. And the C_max and area under the plasma concentration-time curve from time 0 to infinity increases in an apparently dose-proportional manner over the dose range studied, indicating linear pharmacokinetics. The mean terminal-phase half-life (t_1/2) is approximately 7-8.5 h for ticagrelor. Inhibition of platelet aggregation (IPA) is dose related and is nearly complete at 2 h at doses of 100-400 mg. Ticagrelor is well tolerated, with no serious or doserelated adverse events or notable changes in laboratory values observed. ^[2]

• Binding assays using P2Y12-transfected CHO-K1 or humanplatelet membranes

  Membranes (5 μg of protein) are added to a 96-well plate containing [¹²⁵I]AZ11931285 (125 pM), [³H]ADP (10 nM), or [³³P]2MeS-ADP (62.5 pM), the required concentration of competitor, and a sufficient volume of buffer (50 mM Tris, 5 mM MgCl₂, 50 mM NaCl, and 0.1% nucleotide-free BSA, pH 7.4) to bring the total volume in each well to 200 μL. Binding studies using platelet membranes and [³H]ADP are performed in the presence of 100 μM (final concentration) MRS2179 to prohibit binding to P2Y1. The signal-to-noise ratios for P2Y12-transfected CHO-K1 cells are approximately 14 for [³H]ADP (specific signal: 895 c.p.m.), 24 for [³³P]2MeSADP (specific signal: 3308 c.p.m.), and 24 for [¹²⁵I]AZ11931285 (specific signal: 3308 c.p.m.). For the studies using platelet membranes, the signal-to-noise ratios are approximately 2 for [³³P]2MeS-ADP and [³H]ADP and 1.5 for [¹²⁵I]AZ11931285, with a specific signal between 100 and 400 c.p.m. In this study, an incubation time of 1 h at 30 癈 is used to allow full equilibrium to be achieved. Thereafter, free radioligand is separated from bound radioligand and counted as described above.

• Cell lines

  BMDMs

• Concentrations

  20 μM

• Incubation Time

  30 minutes

• Method

  Cells were treated with indicated concentration of drug for 30 minutes.