In contrast to direct opiate agonists, which elicit opiate withdrawal symptoms when discontinued in opiate-tolerant people, no evidence indicates the development of tolerance or dependence on naloxone. The mechanism of action is not completely understood, but studies suggest it functions to produce withdrawal symptoms by competing for opioid receptors within the brain (a competitive antagonist, not a direct agonist), thereby preventing the action of both endogenous and xenobiotic opioids on these receptors without directly producing any effects itself.A single administration of naloxone at a relatively high dose of 2 mg by intravenous injection has been found to produce brain MOR blockade of 80% at 5 minutes, 47% at 2 hours, 44% at 4 hours, and 8% at 8 hours. A low dose (2 μg/kg) produced brain MOR blockade of 42% at 5 minutes, 6% at 2 hours, 33% at 4 hours, and 10% at 8 hours. Intranasal administration of naloxone via nasal spray has likewise been found to rapidly occupy brain MORs, with peak occupancy occurring at 20 minutes, peak occupancies of 67% at a dose of 2 mg and 85% with 4 mg, and an estimated half-life of occupancy disappearance of approximately 100 minutes (1.67 hours). Pharmacokinetics
When administered parenterally (non-orally or non-rectally, e.g., intravenously or by injection), as is most common, naloxone has a rapid distribution throughout the body.
Monosomy is a form of aneuploidy with the presence of only one chromosome from a pair. Partial monosomy occurs when a portion of one chromosome in a pair is missing. Human monosomy
Human conditions due to monosomy:

Turner syndrome – People with Turner syndrome typically have one X chromosome instead of the usual two X chromosomes. Turner syndrome is the only full monosomy that is seen in humans — all other cases of full monosomy are lethal and the individual will not survive development. Cri du chat syndrome – (French for "cry of the cat" after the persons malformed larynx) a partial monosomy caused by a deletion of the end of the short arm of chromosome 5
1p36 deletion syndrome – a partial monosomy caused by a deletion at the end of the short arm of chromosome 1
17q12 microdeletion syndrome - a partial monosomy caused by a deletion of part of the long arm of chromosome 17

See also
Anaphase lag
Miscarriage

References


== External links ==