PHARMACOLOGY
From :
http://www.maripoisoncenter.com/ctr/9612naltrexone.html
Below info is per opioid detoxification
Naltrexone
Naltrexone is approved by the FDA for use in opioid detoxification, and alcohol detoxification programs in known substance abusers. Naltrexone is available only in the oral form.
It is a modification of naloxone made by adding a carbonyl group to C-6.
Naltrexone competes with the opioid agonists for the mu, delta, and kappa receptor sites in the central nervous system(3,8. It has an elimination half-life of 3.9-10.3 hours. Once taken, absorption is rapid and almost complete. However naltrexone has an extensive first pass hepatic metabolism so that bioavailability is poor. Only 5-20% of the drug enters the serum. It is metabolized to 6-beta-naltrexol which is a less potent but active opioid antagonist. Only 2% is excreted in the urine unchanged, while the remainder is processed in the liver to naltrexone-glucuronide and 6-beta-naltrexol and then excreted by the kidneys.
For ethanol detoxification, naltrexone doses are given at 50 mg per day, or 100 mg every other day, or 150 mg three times per week. In opioid dependence, a 25 mg test dose is given. If there are no signs of withdrawal, an additional 25 mg is given, then maintenance naltrexone therapy is set at 50-100 mg per day.
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Naloxone : Brand Name, Narcan
From:
http://opioids.com/naloxone/
ABSTRACT
Background: There is evidence that the endogenous opioid system (EOS) is involved in the modulation of mood and
neuroendocrine function. Furthermore, the possible involvement of the EOS in major depression has been postulated, although a clear role has not been established. Methods: The affective and endocrine responses to naloxone administration in seven female depressives and in seven matched controls and their diurnal variations were investigated. Subjects had an i.v. bolus of either 0.2 mg/kg naloxone or saline at two time points (09:00 or 18:00 h) and for 2 days in a single-blind, cross-over design. Results: The basal cortisol plasma levels, both in the morning and in the afternoon, showed higher values (P<0.05) in the depressives. There was a naloxone-induced increase in the adrenocorticotrophic hormone (ACTH), cortisol, and luteinizing hormone (LH) plasma levels, plus a subjective dysphoric effect in both groups. The depressives showed a greater dysphoric effect both in the morning and afternoon (P<0.05), and a blunted cortisol response in the afternoon (P<0.05). There were no differences between groups or time of day in the ACTH or LH responses. Limitations: The sample size was small, but by studying each patient as their own control, plus a matched control for every patient, softens this effect. Finding patients with a major depressive episode free of medication is difficult, and this aspect contributes to the size of the sample. Conclusions: These results suggest that opioid mechanisms may be involved in the HPA axis changes and possibly in mood changes found in depression. The discrepancy between increased sensitivity in depression to mood changes and decreased change in cortisol may indicate a ceiling effect for the latter.
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From :
http://www.yourencyclopedia.net/Naloxone
Naloxone (trade name Narcan) is a drug used to counter the effects of overdosing on opiates such as heroin or morphine.
The drug has an extremely high affinity for the opiate receptors on nerve cells in the brain, and blocks those receptors quickly, often throwing addicts into immediate withdrawal symptoms.
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Carbonyl Group
From:
http://www.thefreedictionary.com/carbonyl%20group
Noun 1. carbonyl group - the bivalent radical CO
chemical group, radical, group - (chemistry) two or more atoms bound together as a single unit and forming part of a molecule
carbonyl - a compound containing metal combined with carbon monoxide
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Mu, delta, and kappa receptor.
From :
http://www.thebrain.mcgill.ca/flash/i/i ... roine.html
There are three kinds of receptors widely distributed throughout the brain: mu, delta, and kappa receptors.
These receptors, through second messengers, influence the likelihood that ion channels will open, which in certain cases reduces the excitability of neurons. This reduced excitability is the likely source of the euphoric effect of opiates and appears to be mediated by the mu and delta receptors.