PhenylephrineHCl(1,2,3,4-tetrahydro-4,8-di hydroxy 2-methyl isoquinoline

PhenylephrineHCl (1,2,3,4-tetrahydro-4,8-dihydroxy-2-methylisoquinoline) is a structurally related API impurity derived from the parent drug phenylephrine. It features a tetrahydroisoquinoline core substituted with hydroxy groups at positions 4 and 8, a methyl group at position 2, and a hydrochloride salt. The compound arises via oxidative degradation of phenylephrine, retaining the core isoquinoline scaffold but with altered oxygenation patterns. Its distinct hydroxylation profile and methyl substitution confer unique chromatographic and spectroscopic properties. This impurity serves as a critical HPLC reference standard for quantifying degradation products in phenylephrine formulations.