ratios in plasma of tryptophan ( trp ) and tyrosine ( tyr ) to other large neutral amino acids were determined in 26 endogenous depressives before and after treatment with nortriptyline in doses adequate to achieve a steady-state serum level between 70 and 130 ng/ml , i.e. , within the recommended therapeutic range .
C0032105
plasma
C0229671
serum