Methods of modifying behaviour 1: Agonist and antagonist substitution Flashcards
Agonist substitution: Methadone
An agonist is a chemical that binds to a post synaptic receptors and activates that receptor to produce a response. Agonists are designed to imitate the action of another sustance like heroin. An agonist used in the treatment of addiction is methadone , used to treat addiction to opiods like heroin and id produced synthetically to mimic some of the effects of heroin.
Agonist substitution: Methadone (Uses)
Methadone is used as a part of a maintenance treatment. It’s aim is to give heroin users a substitute, it will reduce cravings and prevent withdrawal symptoms. it has some of the effect of heroin but doesn’t give people th same ‘high’. Over time, the doseage of methadone should be reduced over time (detoxification) until the individual stops using it completely (abstinence).
Agonist substitution: Methadone (Dosage)
National Institute for Health and Care Excellence (NICE) guidelines in the UK suggest an intial does of 10-40 mg each day, it is increased by up to 10 mg daily until no signs of withdrawal or intoxication are seen. The individual can maintain a dosage of 60-120 mg daily, typically administered orally as a green liquid to avoid needle-related risks, but it can also be taken in tablets or injections. A doctor, nurse or pharmacist sees patients each day for the first 3 months until they are able to continue without supervision. Supervision ensures correct dosages and prevents multiple doses at once or selling methadone to others, and it is recommended to provide methadone maintenance treatment alongside psychological support to prevent misuse and addiction.
Antagonist substitution: Naltrexone
Antagonist binds to a receptor but rather than causing a reaction, it blocks the usual function of a particular substance. An antagonist used in treating addiction is naltrexone. It is primarily used in the abstinence stage of recovery from addiction. It blocks euphoric and pleasurable effects associated with opiods and it makes them less rewarding.
Antagonist substitution: Naltrexone (Uses)
NICE UK guidelines state that naltrexone should be used by individuals who have stopped opioids and are highly motivated to stay drug-free. It is available as oral medication but it could be an implant, or depot injection. This currently only avaliable in the USA and Russia. Additionally, naltrexone might be offered for case of alcoholism. It is recommened that it is offered with psychological intervention and should be used after withdrawal from alcohol has occured. It is used for up to a 6 month period and users should be kept under supervision to ensure they have not started drinking again. The National Health and Medical Research Council (NHMRC) in Australia recently suggested that it could also be used for gamblers as well, however more research has to been done for its usuage.
Effectiveness: Effectiveness of methadone
NICE assessed 31 reviews of its effectiveness, including 27 randomised controlled trials. They found higher levels of retention for people using methadone than placebo or no treatment and lower rates for illicit opioid use. One meta-analysis concluded that methadone is effective as a maintenance treatment as long as the dosage is adequate. (Van de Brink and Haasen, 2006)
Effectiveness: Effectiveness of naltrexone
NICE reviewed 17 studies concerning the effectiveness of naltrexone for heroin addiction. Overall, the study found conflicting results, with many randomised controlled trials showing no significant difference between naltrexone and a control treatment for retention. However, when the results were pooled, naltrexone was associated with reduced relapse rates, especially in highly motivated patients, who were closely monitored and provided additional support. Lahti et al (2010) tested the effectiveness of naltrexone on a small sample of gamblers who were instructed to take it before gambling or when they felt the urge to. They found significant decreases in gambling levels although they highlight that further research is needed e.g. with a placebo for comparison.
Effectiveness: Comparing methadone and burprenorphine
An alternative to methadone is burprenophine, it is milder and has both agaonist and anatagonist properties. It activated opioid receptors to produce an opiate effect like methadone (agonist) but it also blocks the euphoria in a similar way to naltrexone (agonist). An advantage of burprenorphine is there is less risk of overdose due to its ‘ceiling effect.’ Marteau et al (2015) analysed data for a 5 year period and concluded that it was 6 times safer than methadone. However, methadone is still the preferred choice in the UK. The methadone treatment is more effective in retaining patients due to the addict’s preference for the feeling it provides, making them more likely to continue treatment (Whelan and Remski, 2012).
Ethical implications: Ethical criticisms of the use of methadone
There are some side effects that need to be taken into be taken into consideration. For example, when methadone interact with other drugs such as alcohol and antidepressants to cause respiratory problems. There is also a danger of overdose if an addict combines methadone with other drugs. The Office for National Statistics reported that in 2013, methadone was responsible for 429 deaths in the UK. Critics argue that methadone creates another addiction, and prolonged use without proper support can hinder individuals from reaching the detoxification and abstinence stages, highlighting the need for proper support.
Ethical implications: Side effects of naltrexone
A key with the use of naltrexone as a treatment is that there is greater risk of overdose. If the individual chooses to return to taking a drug they will need more of it to feel the same effects and therefore more likely to overdose. This is why people taking naltrexone will need to be carefully monitored for issues with liver function and if they are still opioid dependent it can cuase withdrawal symptoms, as naltrexone can displace the opioids still in the system from receptors.
Social implications: Financial cost of methadone to society
The Centre for Policy Studies (Gyngell, 2011) said that prescribing methadone is said to be an expensive failure as it costs both society and the 320,000 problem drug users on benefits. I would be more beneficial to use that expense to fund a rehabilitation center which more directly encourages abstinence. The charity DrugScope disputed their report stating that they overestimated the cost of prescribing methadone. They highlighted that the National Audit Office actually stated drug treatment is good value for money for the taxpayer as methadone treatments cause addiction to be more manageable allowing addicts an easier time functioning in society.
Social implications: Methadone and criminality
The National Treatment Agency (2009) treating heroin users with methadone has an immediate positive effect on society by reducing their criminality. They suggest that rates of offennding are reduced by half when addicts are in treatment. However, the Centre for Policy Studies report (Gyngell, 2011), clamied that drug related recidivism has continued to rise despite the availability of drug treatments e.g. methadone. Another possible issue is that by setting up methadone programmes centred on a particular area, groups, of addicts are convenning in a particular place and people are concerned about possible increases in crime and antisocial behaviour in the neighbourhood. However, research in the USA suggests that this is not the case, Boyd et al (2012) researched treatment centres in Baltimore and found crime rates around them were similar to the surrounding areas.
