Linear increases in circulating naltrexone and 6β-naltrexol concentrations occur over an oral dose range of 50 to 200 mg. Naltrexone does not appear to be accumulated with repeated once-daily oral administration and there is no change in time to peak concentrations with repeated administration.The plasma protein binding of naltrexone is about 20% over a naltrexone concentration range of 0.1 to 500 μg/L. Its apparent volume of distribution at 100 mg orally is 16.1 L/kg after a single dose and 14.2 L/kg with repeated doses.Naltrexone is metabolized in the liver mainly by dihydrodiol dehydrogenases into 6β-naltrexol (6β-hydroxynaltrexone). Levels of 6β-naltrexol are 10- to 30-fold higher than those of naltrexone with oral administration due to extensive first-pass metabolism. Conversely, 6β-naltrexol exposure is only about 2-fold higher than that of naltrexone with intramuscular injection of naltrexone in microspheres (brand name Vivitrol). 6β-Naltrexol is an opioid receptor antagonist similarly to naltrexone and shows a comparable binding profile to the opioid receptors. However, 6β-naltrexol is peripherally selective and crosses into the brain much less readily than does naltrexone. In any case, 6β-naltrexol does still show some central activity and may contribute significantly to the central actions of oral naltrexone. Other metabolites of naltrexone include 2-hydroxy-3-methoxy-6β-naltrexol and 2-hydroxy-3-methoxynaltrexone. Following their formation, the metabolites of naltrexone are further metabolized by conjugation with glucuronic acid to form glucuronides.
A degloving injury is a type of avulsion in which an extensive section of skin is completely torn off the underlying tissue, severing its blood supply. It is named by analogy to the process of removing a glove. Effects
Typically, degloving injuries affect the extremities and limbs; in these cases, they are frequently associated with underlying fractures. Any injury which would induce degloving of the head or torso is likely to be lethal. However, controlled facial degloving is often featured in plastic surgery. Degloving injuries invariably require major surgical interventions. Treatment options include replantation or revascularization of the degloved skins, or when these are not possible, skin grafts or skin flaps. While the preservation of the extremities and limbs is normally preferred, in some cases amputations may be advised or required. Post-operative physiotherapy is of particular importance for degloving injuries involving the hand. Other animals
Many small mammals are able to induce degloving of their tails to escape capture; this is comparable to tail autotomy in reptiles. References
External links
Report on degloving injuries in children