ABSTRACT
Rifampin is a potent inducer of hepatic enzymes and is well documented to cause many clinically significant drug interactions. Studies in normal volunteers have shown its ability to decrease circulating levels of thyroid hormone, while having no effect on thyroid-stimulating hormone (TSH). Reports of rifampin's effects on patients on hormone replacement in the clinical setting are of interest since we believe only one such case has been described. We report the case of a man, stable on levothyroxine, who exhibited significantly elevated TSH levels during therapy with rifampin. Thyroid-stimulating hormone levels returned to baseline 9 days after discontinuance of rifampin.
Subject(s)
Rifampin/adverse effects , Thyroxine/adverse effects , Drug Interactions , Enzyme Induction/drug effects , Humans , Hypothyroidism/drug therapy , Liver/enzymology , Male , Middle Aged , Rifampin/administration & dosage , Surgical Wound Infection/drug therapy , Thyrotropin/blood , Thyroxine/administration & dosageABSTRACT
Rates of energy expenditure (J/kg fat-free mass (FFM) per min) in normal weight, 'small-eating' men were compared with those obtained for normal weight (n 8) and underweight (n 5) 'large-eating' men. For the matched groups of 'large-' and 'small-eaters' there were no differences in resting metabolic rate (RMR) measurements but during controlled daily activities there was a small but significant increase (P < 0.05) in energy expenditure in the 'large-eaters'. These results contrast with those obtained for the unmatched groups where energy requirements were about 10% (P < 0.01) higher in the underweight 'large-eaters' at rest but were not different during the more energetic (walking) activities. However, after adjustment for differences in FFM between these two groups, the resting energy expenditures of the 'large-eaters' (82.54 (SE 1.51) J/kg FFM per min) were similar to those of the 'small-eaters' (81.87 (SE 1.51) J/kg FFM per min). Oral temperatures were significantly higher in the matched (0.35-0.65 degrees) and unmatched (0.7-0.9 degrees) 'large-eaters' both at rest and during the different activities, but the thermic effect of food (50 kJ/kg FFM) was one fifth lower (not significant) in both groups of 'large-eaters'. These results provide little evidence for any major metabolic differences between groups of 'large-eating' and 'small-eating' men.
Subject(s)
Energy Metabolism , Feeding Behavior/physiology , Adult , Basal Metabolism , Body Temperature Regulation , Body Weight , Calorimetry, Indirect , Humans , Male , Matched-Pair Analysis , Middle Aged , Nitrogen/urine , Oxygen Consumption , Physical Exertion , Proteins/metabolismABSTRACT
This study examined the anaerobic and aerobic contributions to muscle metabolism during high intensity short duration exercise. Six males [mean (SD): age 25.0 (6.0) years, height 179.0 (8.2) cm, mass 70.01 (7.42) kg, VO2max 4.63 (0.53) l.min-1, body fat 12.7 (2.3)%] performed three counterbalanced treatments of 30, 60 and 90 s of maximal cycling on an air-braked ergometer. All treatments were also performed on days when biopsies were not taken from the vastus lateralis muscle and cannulae not inserted into a forearm vein to ascertain whether these procedures adversely affected performance. The mean results can be summarised as follows: (Table: see text). The muscle lactate and O2 deficit data suggested that 60 and 90 s were more appropriate durations than 30 s for assessing the anaerobic capacity on an air-braked cycle ergometer. The mean power outputs also indicated that the invasive procedures did not adversely affect performance [corrected].
