Discussion on relative drug harm Flashcards
Describe prevalence of drug use in the UK
One consideration in considering relative drug harm is prevalence of use:
Extent and trends in drug use among adults, including separate analysis of young adults (16 to 24-year-olds);
Frequency of drug use in the last year;
Drug use, by personal, household and area characteristics, and lifestyle factors;
Use of novel psychoactive substances (NPS);
Perceived ease of obtaining illegal drugs
different drugs are taken at greater levels in different places
so is prevalence the best way to measure relative drug harm
4 ways of measuring physical harm
prevalence is important, but physical harms such as drug specific mortality, drug related mortality, drug specific damage, and drug related damage need to be considered
Drug specific mortality:
intrinsic mortality of the drug as ratio of lethal dose and standard dose
drug related mortality:
extent to which life is shortened by using drug eg through road traffic accidents or death of secondary blood-borne viruses through sharing needles.
drug specific damage: damage to health through the drug eg cirrhosis, seizures, strokes, cardiomyopathy, stomach ulcers
drug related damage: drug related damage to physical health, blood-borne viruses, emphysema, damage from cutting agents
Injury: use of drug increases injury to others both directly and indirectly- eg domestic voilence, road traffic accidents
What is psychological harm of drugs
The extent to which a drug creates a propensity or urge to continue to use despite adverse consequences
Drug specific impairment of mental functioning- eg amphetamine induced psychosis, ketamine intoxication
Drug related impairment of mental functioning such as mood disorders secondary to drug users lifestyle or drug use
What is social harm that can come from drugs
Social- harm to self and harm to others?
Does the drug affect crime, environment (toxic waste from amphetamine factories or discarded needles), family adversities (eg child neglect), international damage (eg international crime
Or deforestation), economic cost (eg loss of productivity), community (decline in rep of community), loss of tangibles, loss of relationships
How can expert ranking be used to assess drug harm
Analysis undertaken via a two-stage process:
The UK Advisory Council on the Misuse of Drugs (ACMD) met in 2009 to determine drug harm criteria
The Independent Scientific Committee on Drugs (ISCD) – a new organisation of drug experts independent of government interference – was convened in 2010 to develop a multicriteria decision analysis (MCDA) model
MCDA model assessed scores for 20 representative drugs that are relevant to the UK and which span the range of potential harms and extent of use
Issues with this system:
Does this approach depend too heavily upon subjective personal criteria?
Does this approach take into account the total number of users and/or frequency of drug use?
What is drug harm evaluation criteria
A total of sixteen harm criteria were identified
Nine criteria related to the harms that a drug produces in the individual and seven to the harms to others both in the UK and overseas
Harms were clustered into five subgroups representing physical, psychological, and social harms
this can be social, economic, environmental
what are drug harm scores
Total harm score for all the drugs and the part score contributions to the total from the sub-groups of harms to users and harms to others
Most harmful drugs to users were heroin (34), crack cocaine (37), and methamphetamine (32), whereas the most harmful to others were alcohol (46), crack cocaine (17), and heroin (21)
When two part-scores were combined, alcohol was the most harmful drug followed by heroin and crack cocaine
Most harmful drug to others was alcohol by a wide margin
Most harmful drug to users was crack cocaine followed closely by heroin
Methamphetamine was next most harmful to users, but it was of little comparative harm to others
Alcohol, with an overall score of 72, was judged to be most harmful, followed by heroin at 55, then crack cocaine with a score of 54
Only eight drugs scored, overall, 20 points or more
Drug-specific mortality was a substantial contributor to five of the drugs (alcohol, heroin, γ-hydroxybutyric acid [GHB], methadone, and butane), whereas economic cost contributed heavily to alcohol, heroin, tobacco, and cannabis
How can we measure the harm from drugs through toxicology indices?
Therapeutic index; the ratio of the median lethal dose (LD50) to the median effective dose (ED50) – provides a safety ratio
UNODC Illicit Drug Index; combination of a doseindex(the ratio between the typical dose and a lethal dose) and a toxicologyindex(concentration levels in the blood of people who died from overdose compared with the concentration levels in persons who had been given the drug for therapeutic use)
Ratio of number of deaths associated with a substance to its availability (number of users as determined by household surveys, number ofseizures by law enforcement agencies and estimates of the market size)
Some considerations however:
Do toxicology-based indices and the margin of exposure take into account the range of harms (e.g., physical, psychological, social) that are incorporated into expert rankings?
What is the margin of exposure
The margin of exposure (MOE) is defined as the ratio between the toxicological threshold (benchmark dose) and estimated human intake
Median lethal dose values from animal experiments used to derive the benchmark dose
For daily drug use estimated using probabilistic analysis:
The lower the MOE, the larger the risk for humans
UK drug legislation and harm
Taxation
Sales
Age of purchase
What is the misuse of drugs act 1971
Means for controlling drugs (Class A – C)
Grade penalties for drug possession and trafficking
Advisory Council on Misuse of Drugs recommends classification of new or existing drugs that may be misused
Psychoactive substances Act 2016
The Psychoactive Substances Act 2016 covers substances by virtue of their psychoactive properties, rather than the identity of the drug or its chemical structure:
All of these factors have been used to form this act:
Receptor binding assays
functional assays
relevant literature
Accounts from a witness of behaviour exhibited by an individual who has taken the substance
Scientific evidence of drug harm
A constantly increasing number of novel psychoactive substances, with limited scientific evidence on relative drug harm
What is needed?
In vitro studies (e.g., cell lines)
Animal model studies
Human studies – acute and chronic effects?
