Validated liquid chromatography‐mass spectrometry method for the quantification of glycogenolysis phosphorylase inhibitor in mouse tissues – 5‐isopropyl‐4‐(2‐chlorophenyl)‐1‐ethyl‐1, 4‐dihydro‐6‐methyl‐2, 3, 5‐pyridinetricarboxylic acid ester disodium salt hydrate. Issue 20 (7th September 2022)