Naltrexone is not metabolized by the cytochrome P450 system and has low potential for drug interactions.The elimination of naltrexone is biexponential and rapid over the first 24 hours followed by a third extremely slow decline after 24 hours. The fast elimination half-lives of naltrexone and its metabolite 6β-naltrexol are about 4 hours and 13 hours, respectively. In Contrave oral tablets, which also contain bupropion and are described as extended-release, the half-life of naltrexone is 5 hours. The slow terminal-phase elimination half-life of naltrexone is approximately 96 hours. As microspheres of naltrexone by intramuscular injection (Vivitrol), the elimination half-lives of naltrexone and 6β-naltrexol are both 5 to 10 days. Whereas oral naltrexone is administered daily, naltrexone in microspheres by intramuscular injection is suitable for administration once every 4 weeks or once per month.Naltrexone and its metabolites are excreted in urine. Pharmacogenetics
Tentative evidence suggests that family history and presence of the Asn40Asp polymorphism predicts naltrexone being effective. Chemistry
Naltrexone, also known as N-cyclopropylmethylnoroxymorphone, is a derivative of oxymorphone (14-hydroxydihydromorphinone). It is specifically the derivative of oxymorphone in which the tertiary amine methyl substituent is replaced with methylcyclopropane. Analogues
The closely related medication, methylnaltrexone (N-methylnaltrexone), is used to treat opioid-induced constipation, but does not treat addiction as it does not cross the blood–brain barrier. Nalmefene (6-desoxy-6-methylenenaltrexone) is similar to naltrexone and is used for the same purposes as naltrexone. Naltrexone should not be confused with naloxone (N-allylnoroxymorphone), which is used in emergency cases of opioid overdose.
Julian Nowak later proposed the name mycoplasma for certain filamentous microorganisms imagined to have both cellular and acellular stages in their lifecycles, which could explain how they were visible with a microscope, but passed through filters impermeable to other bacteria. Later, the name for these mycoplasmas was pleuropneumonia-like organisms (PPLO), broadly referring to organisms similar in colonial morphology and filterability to the causative agent (a Mycoplasma species) of contagious bovine pleuropneumonia. At present, all these organisms are classified as Mollicutes and the term Mycoplasma refers solely to the genus. Species that infect humans
Species of Mycoplasma, other than those listed below, have been recovered from humans, but are assumed to have been contracted from a non-human host. The following species use humans as the primary host:

Pathophysiology
Mycoplasma species have been isolated from women with bacterial vaginosis. M. genitalium is found in women with pelvic inflammatory disease. In addition, infection is associated with increased risk of cervicitis, infertility, preterm birth and spontaneous abortion. Mycoplasma genitalium has developed resistance to some antibiotics. Mycoplasma species are associated with infant respiratory distress syndrome, bronchopulmonary dysplasia, and intraventricular hemorrhage in preterm infants. Characteristics
Over 100 species have been included in the genus Mycoplasma, a member of the class Mollicutes. They are parasites or commensals of humans, animals, and plants. The genus Mycoplasma uses vertebrate and arthropod hosts. Dietary nitrogen availability has been shown to alter codon bias and genome evolution in Mycoplasma and Phytoplasma.Mycoplasma species are among the smallest free-living organisms (about 0.2 - 0.3 µm in diameter).