Naphthoxylactic acid

After a single oral dose of 80 mg administered to 6 subjects, the following mean peak concentrations of drug and metabolites were found in the plasma after 2 hours propranolol 0.05 pg/ml, naphthoxylactic acid 0.53 pg/ml, 4-hydroxypropranolol 0.009 pg/ml, naphthoxyacetic acid 0.024 pg/ml, propranolol glycol 0.005 pg/ml (D. W. Schneck et al., Clin. Pharmac. Ther., 1980, 27, 744-755). 

Smith MT, Livingstone I, Hooper WD, Eadie MJ, Triggs EJ. Propranolol, propranolol glucuronide, and naphthoxylactic acid in breast milk and plasma. Tlier Drug Monit 1983 5(l) 87-93. 

Aromatic hydroxylation at C-4 N-dealkylation Oxidative deamination Oxidation of deaminated product to naphthoxylactic acid Conjugation with glucuronic acid O-dealkylation... 

Two cytochrome P450 isoenzymes, CYP2D6 and CYP2C19, are involved in the metabolism of propranolol. The 4-hydroxylation of propranolol co-segregates with the debrisoquin polymorphism, but the side-chain oxidation to naphthoxylactic acid is catalysed in part by the mephenytoin isoenzyme. 

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