Drugs week 1 Flashcards
What is addiction?
- is a construct
- when drug has substantial long term negative effects on the life of an individual we consider it addiction.
what is psychopharmacology?
study of drug-induced changes in mood, cognition and behaviour
drugs can be prescribed medications, legal recreational substances or illegal recreational substances. Come from natural (animal/plant) or synthetic (manufactured) sources.
drug action vs drug effect
action : role the drug has on the neurochemistry.
effect : role the drug has on physiology.
Explain the role of route of administration
route causes dramatic difference in the onset, intensity and duration, slower onset the more gradual build up and longer it will last.
inhalation
injection
snorting
ingestion
why is there different routes of administration?
unprocessed drugs : cannot be injected only smoked, snorted or cooked
personal preference
speed which drugs act
Young, Haven and Leukefeld, 2010 study
212 rural users vs 111 urban users
prescription drug abuse (Oxycodone)
urban = swallow
rural = snort / other alternative routes, linked to drug problem severity.
study : effect of route of administration of heroin on transition to regular use.
395 heroin users in London, those injecting almost 5 times more likely to progress to daily use within 1-3 weeks of first use than other methods. Implication for interventions and cultural norms.
what is the link between route of administration and cultural norms
legal policies can influence ROA for certain substances
legal prescription for opiates in USA vs Intravenous heroin use, changing global views on cannabis and tobacco have affect ROA
Changes in technology.
what study demonstrates cross-cultural differences in cannabis ROAs
Hindocha et al, 2016 : 33,000 pps from 12 countries in Europe, USA, Canada, brazil, Mexico, Australia and new Zealand.
66% smoked cannabis with tobacco globally
most common in Europe - 77%
uncommon in America : 16% , consistent with image of smoking in USA.
what study demonstrates difference in cannabis due to legalisation
Borodovsky et al (2016) : higher incidence for vaping and edibles in medical marijuana law states, longer duration = higher incidence of vaping and edibles.
What different pharmacokinetics account for different levels of absorption in the bloodstream
more barriers drug has to travel, slower effect, more likely drug is to be degraded
- degree to which drug is soluble
- degree of ionization (less likely to cross cellular membrane)
- size of molecule (smaller = faster)
- difference in drug concentration on either side of the membrane.
explain how the different pharmokinetics effect absorption when there is different ROA
intravenous: no absorption, directly to blood stream and move to site of drug action
inhalation: high difference in chemical concentration from lung to blood stream, rapid movement down gradient, high lipid solubility and small particles.
mucous membrane : several layers of cells to cross but aided by difference in concentration
oral : very slow, often poor because of degradation by stomach acid and enzymes
How can drugs be distributed in the body following absorption
- stored in body tissue
- remains in blood stream
- metabolized
rapid absorption = more distribution = less drug to the brain
What does the drug have to do to the brain in order to have an effect?
must penetrate the blood-brain barrier. drugs of abuse all pass the BBB easily.
Explain the difference between heroin and morphine
both opiates
heroin (diamorphine) : lipid soluble - crosses BBB more easily, last couple of minutes, then converted to morphine. used in emergency.
what is oxycontin, and what are the issues?
Oxycontin releases Oxycodone, but unlikely just oxycodone, this get released slowly.
Painkiller.
- marketed as a safter drug
- no advantage over other potent opioid
- more access to the drug now = increased death rates.
- create more heroin addiction : gateway drug.
How did Oxycontin become so widely abused?
- thought to have lower abuse properties because of the slow release formula
- changing the route of administration eliminate the slow release property
- misleading claims about addiction
- marketing: 2001 company spent 200 million dollars, target physicians
- stater coupon programme for oxycontin (fixed ratio, scheduled reinforcement)
- USA permits advertising of medications on TV
- USA compared to Europe are not as strict on prescription: internet pharmacy, easily prescribed.
what is the opioid use in the UK?
0.5% UK high risk opioid users.
2,219 deaths from opioids in 2021 in England and Wales, half of all drug related deaths.
Heroin didn’t account for majority of deaths, but does for use of single drug.
deaths in USA: 0.024%
England and Wales = 0.0037%
what is drug elimination
body work to eliminates drugs through metabolism (break down of drug into metabolites that are either active or inactive, lungs, sweat, saliva, urine) reverse of absorption, usually takes place in liver, exerted by kidneys.
explain how the rate of metabolism and extraction can be effected?
rate usually faster due to drug concentration on either side of the kidney membrane, but then slows
alcohol is the exception - metabolized at a constant rate.
what is meant by drug half-life
the plasma concentration of a drug is halved after one elimination half-life. After one half -life the amount of drug remaining in the body is 50%. Amount taken doesn’t effect half life.
