Influence of a very low calorie diet on the clearance of oxazepam and antipyrine in man

A very low calorie diet (Prodi) was administered to eleven otherwise healthy obese subjects for fourteen days. The daily intake of protein was 52.7 g and carbohydrate 25.7 g, corresponding to 360 kcal. The clearance of oxazepam and antipyrine was investigated before and after the diet period. Total oxazepam clearance was 1.04 ml.min-1.kg-1 and it decreased 0.88-fold after the diet. The mean clearance of unbound oxazepam was correspondingly reduced 0.88-fold. The elimination half-life increased to 1.22-times the control value, 7.9 h. No significant change was found in the volume of distribution or protein binding of oxazepam. Antipyrine clearance, estimated by the one-sample technique, was 52.4 and 51.8 ml.min-1, before and after the diet, respectively. It appears that a very low calorie diet with a sufficient protein and a very low carbohydrate content decreases the metabolism of oxazepam by glucuro-conjugation, whereas no effect was seen on the oxidative metabolism of antipyrine.