Psychopharmacology II Flashcards
what is alcohol and how is it ingested?
one of the most consumed drugs, which is ingested by drinking
categorised as a depressant drug
at lower doses, what does alcohol produce?
behavioural stimulation
at higher doses, what does alcohol produce?
depression
what does the dose-response curve for alcohol show?
behavioural stimulation increases alongside dose increase, which causes inhibitory effects to kick in
how does alcohol effect the brain?
it enhances inhibitory neurotransmitters by bonding to GABA-A receptors and acting as an allosteric modulator
this enhances the flow of chloride ions into the brain and enhances the effect of GABA
how else does alcohol effect the brain?
it inhibits excitatory nerve transmission in NMDA (glutamate) receptors
what indirect effects does alcohol have?
indirect effects of neurotransmission in serotonin, opioid, and dopamine systems in the brain
increases mesolimbic dopamine transmission from action at cannabinoid receptors
long-term effects of alcohol use
heavy alcohol use can lead to negative general health issues, such as liver cirrhosis, increased risk of cancer, and foetal alcohol syndrome
how can long-term alcohol use affect the brain?
development of Korsakoff’s syndrome and vitamin deficiencies in thiamine/B1
this can lead to memory problems such as dementia
what happens when the brain adapts to chronic alcohol use?
leads to withdrawal syndrome, caused by a rebound of excitability
what is cocaine?
a stimulant drug extracted from leaves of the coca plant
route of administration for cocaine
via nasal mucous membranes or inhalation
physiological effects of taking cocaine
increased temperature, blood pressure, and heart rate- leading to potential heart problems
effects of cocaine on the brain
cocaine blocks dopamine transporters, which reduces re-uptake of dopamine into the neurone. to prolongs it duration in the synapse
indirectly enhances the effects of dopamine, making cocaine an indirect dopamine agonist
chronic, physical, and psychological effects of cocaine
can cause problems with lung congestion if smoked or damage to the nasal membrane if snorted
what can stimulant effects of cocaine lead to?
general cardiovascular problems or drug induced psychosis, e.g., formication
amphetamines
these have similar psychological effects to cocaine, and can be swallowed, snorted, injected, or smoked
types of synthetic stimulants
d-amphetamine
methamphetamine
differences between synthetic stimulants
methamphetamine is more lipid-soluble than d-amphetamine, meaning it crosses the membrane and is absorbed into the brain more quickly
this may explain its higher usage
effects of amphetamines
has initial effects of euphoria, wellbeing, and alertness which is followed by a ‘crash period’ consisting of irritability, paranoia and tremors
long-term use can lead to psychosis
nicotine
administered in tobacco products and nicotine replacement products
what is nicotine?
a direct agonist and a stimulant drug- acts as an agonist at acetylcholine receptors
this increases the release of neurotransmitters such as dopamine
what does nicotine not block?
cholinergic receptors
stimulant effects of caffeine
when taken acutely, it can increase alertness and motor coordination
those with higher sensitivity can experience negative effects such as panic attacks or anxiety
what is caffeine?
a direct antagonist acting at adenosine receptors
what does caffeine have a natural link to?
dopamine- as adenosine receptors inhibit the activation of dopamine receptors
by reducing inhibition, dopamine signalling is increased- meaning caffeine becomes a stimulant
types of opiates
can be naturally occurring in plants (morphine and codeine) or synthesised in a lab (heroin, fentanyl, or oxycodone)
how does heroin undergo metabolism?
heroin can cross the blood-brain barrier more easily than morphine
it is metabolised into morphine in the brain, meaning that morphine causes the biological effect
types of opioid receptors
delta
epsilon
kappa
mu
sigma
why has the mu receptor received most attention?
action at this receptor brings about pain relieving effects of opioid drugs and is responsible for being dependence inducing
what are the psychoactive properties of heroin mediated by?
agonist action at mu receptors
what do endogenous opioid receptors (beta endorphin) bind to?
mu opioid receptors
morphine and heroin bind to these same receptors in the brain
cannabis
the cannabis sativa plant contains active chemicals, and many effects are caused by the main ingredient Delta 9-THC
properties of THC
THC is metabolised and eliminated in urine
it is lipid-soluble so must be transformed into water-soluble molecules to be eliminated
how does transformation of THC effect drug action?
the slow elimination and quick storage in fat is the reason for prolonged cannabis action
cannabis receptors in the brain
- CB1 and CB2 receptors
THC and cannabis receptors
THC acts as a direct agonist at these receptors, which enhances cannabinoid neurotransmission
this also has effects on increasing dopamine release
which different mediating factors can underlie individual differences contributing to drug effects?
- kinetic differences
- pharmacodynamic differences
- idiosyncratic differences
kinetic differences
a different amount of drug reaches the site of action for same doses
pharmacodynamic differences
different psychological responses for the same drug concentration at the site of action
idiosyncratic differences
people may experience an atypical drug reaction due to genetics or prior exposure to toxins
body size and composition
the same dose produces a smaller response in a larger person, as it is diluted by a larger vascular system and distributed in greater blood volume
how can body size and composition be mediated?
doses should be titrated, so a larger person receives the same dose effect
age- effect of liver
metabolism can be affected by a change in liver mass and decrease in liver function, meaning it is unable to metabolise as many drugs
age- effect of kidneys
kidneys are less able to excrete drugs into the urine
age- other drugs
drug-drug interactions could alter the response
40% of older people do not take drugs as directed- issues with compliance
sex
women have lower plasma volume and a higher proportion of body fat, which can affect whether the drug is retained in fat
hormonal effects can interact responses to a drug, and some drugs may be metabolised differently
how is alcohol metabolised?
it is metabolised by the enzyme alcohol dehydrogenase, which is critical for converting alcohol into the metabolite acetaldehyde
what is acetaldehyde?
highly reactive and toxic- if this builds up it can have adverse effects, which may be the cause of hangovers
acetaldehyde is transformed into acetic acid to be removed from the body
biotransformation of alcohol- sex
equivalent amounts of alcohol can have a greater effect on women than men, due to a smaller vascular capacity and lower levels of gastric alcohol dehydrogenase
this means less alcohol will enter their blood
biotransformation of alcohol- presence of food in the stomach
drinking on a full stomach increases likelihood of alcohol being metabolised by gastric alcohol dehydrogenase
the presence of food affects the amount of absorption
biotransformation of alcohol- genetics
racial and ethnic group can affect drug response due to underlying genetic differences, however this is not a perfect market
biotransformation of alcohol- ethnicity
genetic ancestry may be more relevant than self-identified race. individual knowledge of the genetic profile is most accurate for drug predictions
what can be found in individuals of asian heritage?
variants of the enzyme aldehyde dehydrogenase. these variants are linked to an increased response for alcohol, resulting in a reduced breakdown of acetaldehyde.
may be the cause of a reduced tendency of drinking in this group.
african american smokers
have a slower rate of nicotine metabolism due to a genetic variation in the enzyme CYP2A6
this means less nicotine is needed to maintain the effects, and they may smoke less extensively
biotransformation of alcohol- sociocultural factors
different racial and ethnic groups experience different socioeconomic and cultural contexts, which can influence whether people try drugs of continue to use them
this might relate to smokeless tobacco products in south asian households
which ethnic groups suffer greater harm from drug use?
women of colour are at greater risk for hypertension, high blood pressure, and HIV/AIDS.
this can be related to difficulty in accessing affordable healthcare and mistrust in providers
tolerance
needing to escalate the dose to experience the same effect
sensitisation
taking less of the drug to experience the same effect
different kinds of tolerance
- metabolic tolerance
- cellular tolerance
metabolic tolerance
the drug is metabolised faster with repeated use
cellular tolerance
target cells adjust their function to compensate for the action of drug on the cell
what is sensitisation more common for?
stimulant drugs, as the desire for the drug is becoming sensitised
placebo effect
a placebo is a drug that has no intrinsic pharmacological activity, but can produce behavioural and physiological effects that are indistinguishable from a real drug
expectancies
whether someone is told specific effects that are likely to occur will affect the response
how can forms of medication influence how people think about the effectiveness of a drug?
blue pills associated with a calming effect
red pills associated with a stimulant effect
smaller pills and larger doses believed to be less effective
what can expectancies have implications on?
how healthcare must present drugs and medication to patients
