BIX 02565 is a potent inhibitor of ribosomal S6 kinase 2 (RSK2, IC50: 1.1 nM).

RSK2:1.1 nM (cell free), PRKD1:35 nM (cell free), LRRK2:16 nM (cell free)

BIX 02565 inhibited RSK2 with IC50 value of 1.1 nM. It also inhibited LRRK2 and PRKD1 with IC50 values of 16 and 35 nM [1]. BIX 02565 elicited >50% inhibition at adrenergic α1A-, α1B-, α1D-, α2A-, β2-, and imidazoline I2 receptors (IC50s: 0.052-1.820 μM) [2].

Infusion of BIX 02565 (1, 3, and 10 mg/kg) in the rat CV screen resulted in a precipitous decrease in both mean arterial pressure (MAP; to -65 ± 6 mm Hg below baseline) and heart rate (-93 ± 13 beats/min). In telemetry-instrumented rats, BIX 02565 (30, 100, and 300 mg/kg p.o. QD for 4 days) elicited concentration-dependent decreases in MAP after each dose (to -39 ± 4 mm Hg on day 4 at T(max)); analysis by Demming regression demonstrated strong correlation independent of route of administration and influence of anesthesia [2].

A monolayer of exponentially growing HLR-CREB cells was prepared and transfected using Effectene with RSK2. Cells were plated into 96-well culture plates, and compounds were added 20 to 24 h after transfection. Luciferase expression (48 h) and activity (5 min) were determined using Steady-Glo per manufacturer's instructions, and results were represented as the percentage luciferase activity relative to the control measured in the absence of inhibitors (percentage of control); the IC50 was fitted to a standard four-parameter logistic equation. Each data point represents an average of triplicate observations [2].

Mean arterial pressure was assessed in conscious, freely moving male Sprague-Dawley rats (n = 6/group) instrumented with telemetry transmitters similar to that described previously. BIX 02565 (30, 100, and 300 mg/kg p.o. QD) was administered as a solution (10 ml/kg) in a 20% hydroxy-propyl-β-cyclodextran vehicle as described previously. Mean arterial pressure was reported from 2 h before (baseline) and 90 h after the first dose; compound was administered at 0, 24, 48, and 72 h. A blood sample was collected from satellite rats (n = 3/group) at 1-h after dose (Tmax) on days 1 and 4 for analysis of plasma drug concentrations by mass spectrometry [2].