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Naltrexone blocks opiate binding to opiate receptors.
Naltrexone implants are the most important therapeutic weapon to prevent opiate overdose.
Whilst being on naltrexone patients are immune to opiate effects including heroin and morphine. The problem is, some people stop taking it because they are OK or they want to use opiates again.
With naltrexone implants patients are covered from 6 weeks to a 6 month period.
Naltrexone (NTX) effectively blocks opiate response, by biding strongly to opiate receptor impeding other opiates to bind after.
One of the problems of NTX is his short half life because of rapid hepatic clearance, besides its poor bioavailavility (approximately 40%).
Depot NTX, for subcutaneous use, was developed to provide long-lasting resistance to opiate drugs in habituated users, and thus facilitate an opiate-abstinent lifestyle.
NTX has been available for at least 30 years and has been used clinically since 1973. This is combined with a polymer (biodegradable plastic) which is registered by the FDA (Food and Drug Administration USA) for implantation in humans.
Whilst being on naltrexone patients are immune to opiate effects including heroin and morphine. The problem is, some people stop taking it because they are OK or they want to use opiates again.
With naltrexone implants patients are covered from 6 weeks to a 6 month period.
Naltrexone (NTX) effectively blocks opiate response, by biding strongly to opiate receptor impeding other opiates to bind after.
One of the problems of NTX is his short half life because of rapid hepatic clearance, besides its poor bioavailavility (approximately 40%).
Depot NTX, for subcutaneous use, was developed to provide long-lasting resistance to opiate drugs in habituated users, and thus facilitate an opiate-abstinent lifestyle.
NTX has been available for at least 30 years and has been used clinically since 1973. This is combined with a polymer (biodegradable plastic) which is registered by the FDA (Food and Drug Administration USA) for implantation in humans.
Current Available Naltrexone Implants
Naltrexone was synthesized in the 1960s and first used clinically in the early 1970s. It soon became evident that its therapeutic potential was undermined by poor compliance and the first studies of depot preparations date from the mid 70s. Human studies were done in the early 1980s and most of the basic science was known by then. I do not know why it took so long to apply it.
The first implants for clinical as opposed to experimental use were made around 1997 by George Malmberg of Wedgewood Pharmacy, Sewell, NJ.
These ‘first generation’ models currently consist of a cigarette-butt size pellet of compressed naltrexone powder with a small percentage of magnesium stearate, which is apparently a normal component of implants but sometimes causes tissue irritation.
‘Second generation’ implants use another established implant technique - embedding naltrexone microspheres in a matrix of biodegradable polymer. The only currently available implant of this type is made by Dr George O’Neill in Perth, WA, Australia. The polymer takes 1-2 years to break down and naltrexone is released for 9 months or more, though opiate blockade may be only partial after about 5-6 months. They are generally well-tolerated and there is no need to include a steroid. Both types of implant are usually inserted with antibiotic prophylaxis and both can block very large amounts of heroin.
Neither of these implants has a product licence even in their country of origin but they are made to appropriate pharmaceutical standards and they are imported officially into in conformity with the regulations of the Medicines Control Agency and with their full knowledge.
The polymer can also be formulated as a liquid vehicle for a depot injection of naltrexone. One US firm has been working on this for over 10 years. Phase 3 trials have been done and it is possible that it may get a product licence in the US soon. Other companies in various countries are working along similar lines.
The first implants for clinical as opposed to experimental use were made around 1997 by George Malmberg of Wedgewood Pharmacy, Sewell, NJ.
These ‘first generation’ models currently consist of a cigarette-butt size pellet of compressed naltrexone powder with a small percentage of magnesium stearate, which is apparently a normal component of implants but sometimes causes tissue irritation.
‘Second generation’ implants use another established implant technique - embedding naltrexone microspheres in a matrix of biodegradable polymer. The only currently available implant of this type is made by Dr George O’Neill in Perth, WA, Australia. The polymer takes 1-2 years to break down and naltrexone is released for 9 months or more, though opiate blockade may be only partial after about 5-6 months. They are generally well-tolerated and there is no need to include a steroid. Both types of implant are usually inserted with antibiotic prophylaxis and both can block very large amounts of heroin.
Neither of these implants has a product licence even in their country of origin but they are made to appropriate pharmaceutical standards and they are imported officially into in conformity with the regulations of the Medicines Control Agency and with their full knowledge.
The polymer can also be formulated as a liquid vehicle for a depot injection of naltrexone. One US firm has been working on this for over 10 years. Phase 3 trials have been done and it is possible that it may get a product licence in the US soon. Other companies in various countries are working along similar lines.
Toxicity
Since naltrexone is a relatively old drug, its properties are correspondingly well known. It appears to have no significant organ toxicity apart from very rare rashes. In particular, there are no reports of clinically significant liver toxicity.