ANTA Alcohol & Other
Further information about the effects and
treatments for different drugs
Naltrexone has recently become available in Australia as a tablet for use in relapseprevention. Naltrexone is an opiate ‘antagonist’, meaning it antagonises, or blocks the effectsof opiates. It works by attaching itself to parts of tissues, called receptor sites, normallyaffected by opiates. However, naltrexone has no opiate-like effects. Compare this to heroinwhich attaches to the same sites but causes a multitude of effects – euphoria, drowsiness,constipation, etc. The individual taking naltrexone will not feel any pleasure from the drug,but it will block any heroin from getting into the tissues.
To use an analogy, think of an office with a number of computer workstations. If activeworkers occupy the seats of these workstations, there is a result. Work gets done as theypunch away at keys on their terminals. These workers are like heroin at tissue (receptor)sites. Now, imagine that these workers seats were taken by people who did nothing. Theseslackers are like naltrexone molecules, blocking the active agents from affecting the tissue.
The primary aim of naltrexone treatment is relapse prevention, to discourage the heroin userfrom using.
Naltrexone works in a similar way with alcohol dependency. The alcoholic taking naltrexonewill not get an effect from alcohol, and is therefore less inclined to start drinking again.
Illicit (and some licit) drugs may be particularly irritating to veins. When injected into limbveins, irritation or infection (phlebitis), or scarring/clotting in the veins may occur(thrombophlebitis). This has been of particular problem with some drug users who injectcertain preparations of the sedative temazepam.
Endocarditis or subacute bacterial endocarditis
Injecting drug use is a risk factor for infection of the valves of the heart (endocarditis). Thisoccurs when a small amount of bacteria is pushed into the bloodstream with a needle.
Endocarditis usually requires long term treatment with high dose antibiotics, and may befatal. It is minimised by the swabbing the site of injection with alcohol prior to injecting (theseswabs are distributed by NSEPs or NSPs).
ANTA Alcohol & Other
Methadone is an opioid (synthetic opiate) that was discovered over 50 years ago. For muchof the last 40 years has been the mainstay of treatment of opiate dependence. This form oftreatment is sometimes termed substitution, as it involves substituting a safer and moremanageable drug for heroin.
Methadone has a long half-life, meaning it stays in the body for a long time. To illustrate this,it is useful to compare half-lives of heroin and methadone. Heroin has a half-life of a fewhours, meaning that a user must periodically ‘top up’ to maintain the desired effect.
Methadone’s half-life is in the vicinity of 1-2 days, meaning that a single dose will usually lastuntil the following day.
In Australia the prescription of methadone to opiate dependent persons is tightly regulated,and these regulations may vary between States and Territories. For example, at time ofwriting the Northern Territory had no provision within its health or drugs and poisons acts toallow for the supply of methadone to treat opiate dependence.
Methadone is not appropriate for all heroin users. It is usually offered as a treatment option tolong term users who can make an informed choice about whether they are willing toundertake this form of treatment. In most parts of Australia, there are GPs and clinics thatcan prescribe and monitor methadone therapy.
For a drug user involved in crime, at risk of overdose or blood borne virus infection or isexperiencing major life disruption due to heroin, methadone can be an enormous help. Whena user is stabilised on methadone, craving for heroin is usually substantially reduced. Use ofheroin while taking methadone often does not produce the same euphoria and is not asappealing. A heroin user can pick up methadone at a pharmacist each day and is monitoredby treatment services, helping to restore some normality and routine.
The downside of methadone is that it is a long term treatment, usually a year or more. It isdifficult for the individual to travel with the requirements for daily dosing. Side effects includedysphoria (low mood), increased sweating, loss of sex drive, puffiness in extremities,constipation and insomnia. These do not occur in everyone and are managed by dosagemodifications. The methadone patient risks overdose if other drugs, including heroin orbenzodiazepines, are used on top of methadone.
ANTA Alcohol & Other
There are some misconceptions surrounding methadone worth addressing:
Opiates, including heroin, reducesaliva which increases the risk ofdental caries. People on methadoneare educated about dental hygieneand encouraged to chew sugar freegum.
While fluid retention may occur withmethadone, the main reason peopleput on weight on methadone isprobably because their appetite isrestored. The commencement of amethadone program is a good timefor educating individuals abouthealthy diet.
withdrawal symptoms from
methadone are more protracted
than heroin, probably because its
half-life is longer. Withdrawal from
heroin may take in the order of 1-2
weeks, whereas withdrawal
symptoms from methadone may
take over 6 weeks. However, this is
managed by very slow reduction in
ANTA Alcohol & Other
Blood borne diseases (Blood borne viruses or BBVs)
People who inject drugs (particularly heroin and amphetamine) are at particular risk of bloodborne viruses. The major BBVs of relevance to injecting drug users are the following.
transmitted by blood, body fluids; sexually transmitted
characterised by a severe acute illness which usually resolves completely
a small percentage of infected individuals develop a chronic carrier state, andthese individuals may progress to chronic liver disease and liver cancer
injecting drug users (IDUs) should be strongly encouraged to undertakeHepatitis B vaccination.
sexual transmission may occur, but this is uncertain
high prevalence of infection in Australian IDUs
most infections progress to a chronic, low grade hepatitis; over severaldecades Hepatitis C may progress to cirrhosis or liver cancer
treatment with a drug called interferon, with or without the addition of anotheragent (ribavirin) is available but is only partially effective.
characterised by a variable period of incubation, often progressing to a severeimmune deficiency illness (AIDS)
blood and body fluid transmission; sexually transmitted
incidence and prevalence in Australian IDUs is low
drug dependent individuals may be at risk of sexually transmitted HIV (andother sexually communicable infections) due to impaired judgement, lifestyleor sex work
information about safe sex and injecting, availability of barrier contraceptives(condoms, dental dams) and clean injection equipment are essential inreducing HIV related harm
Management of injecting drug use should include counselling, testing, vaccination andmanagement of BBVs. The risk of transmission of blood borne diseases is minimised by theuse of clean injection equipment such as provided by needle and syringe exchange services.
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Pharmacokinetics and Relative Bioavailability of Metformin Hydrochloric Acid Sustained Release Tablet in Healthy Volunteers Yi n X i a o - X i n g , Z h a n g Yi - D i , Z h u o H a i - To n g , S h e n J i a n - P i n g , L i L i - M i n , Q i u J u n . ( I n s t i t u t e o f C l i n i c a l P h a r m a c o l o g y, N a n j i n g M e d i c a l U n i v e r s i t y, N a n j i n g 2 1