LONG-TERM EFFECT OF DEXFENFLURAMINE ON AMINO-ACID PROFILES AND FOOD SELECTION IN OBESE PATIENTS DURING WEIGHT-LOSS

In depressive disorders an association between basal pre-treatment pla sma ratios of tryptophan (Trp) and tyrosine (Tyr) to other large neutr al amino acids (LNAA) and the clinical efficacy of serotonergic acting drugs have been established. In order to clarify whether a similar re lation exists in obesity and to elucidate the long-term effect of dexf enfluramine (dF) on plasma amino acid profiles and macronutrient selec tion, we examined 29 obese patients participating in a 12 months doubl e-blind weight loss trial with either dexfenfluramine (dF) (30 mg/day) or placebo (PL) in conjunction with a 4.2-5.0 MJ/d diet. Maximum weig ht loss was obtained after 6 months (dF 12.8 +/- 5.4 kg; PL 13.8 +/- 9 .2 kg, x +/- s.d., ns). Plasma Trp/LNAA and Tyr/LNAA were found to be lower than in normal weight controls and were further reduced during t reatment (p < 0.05), but without differences between dF and PL groups. Macronutrient selection was not affected by the dF treatment. In the placebo group weight loss was associated with a high pretreatment ener gy intake and a high carbohydrate-protein ratio (p < 0.05), A decrease in dietary fat and increase in protein intake (%) and age was found t o explain 82% of the variation in weight loss (p < 0.0005), whereas no correlation could be shown in the dF group. Pre-treatment plasma Trp/ LNAA or Tyr/LNAA and weight loss were not correlated. In conclusion, n either food selection nor basal plasma amino acid profiles were predic tors of weight loss during long-term treatment with dF as an adjuvant to energy restriction, and they were not affected by the drug treatmen t.