AZ7976 (Compound 42), a potent and highly selective agonist for Relaxin Family Peptide Receptor 1 (RXFP1) with a pEC 50 value greater than 10.5, operates through an allosteric mechanism to enhance RXFP1's cAMP signaling, which physiologically elevates heart rate. This property makes AZ7976 a valuable tool in cardiovascular disease research [1].

Compound AZ7976, administered intravenously (initial dose of 1.5 mg/kg followed by continuous infusion at 9.0 mg/kg), significantly elevated the heart rate and mean arterial blood pressure in Sprague-Dawley rats [1]. Pharmacokinetic analysis [1] revealed the following parameters: volume of distribution (Vdss) at 2.3 L/kg, clearance (Cl) at 38 mL/min/kg, and a half-life (t 1/2) of 2.9 hours, with an oral dose bioavailability (F) of 11% at a dose of 1.46 μmol/kg. The observed cardiovascular responses are similar to those seen following activation of the RXFP1 receptor.