Workshop 4: Interactions with drugs Flashcards
Psychopharmacology
Study of drugs that affect the nervous system and behaviour
Drugs of abuse
CNS depressants (e.g. alcohol)
CNS stimulants (e.g. caffine)
Opiates and opioids (narcotics)
—-> can be synthetically made, or painkillers
Hallucinogens (e.g. LSD, psilocybin, mushrooms)
Marijuana
—-> can be a hallucinogen but can be different for individuals
(some have dual roles - e.g. alcohol depresses some systems but stimulates others)
Categories for psychotherapeutic drugs
Categorised for their mechanism for action, physiological effect and chemical structure of the drug
▪ The Anatomical Therapeutic Chemical (ATC) Classification System ▪ International Pharmacopeia (WHO) ▪ European Pharmacopeia ▪ United States Pharmacopeia (USP)
ATC classification system (Anatomical therapeutic chemical)
- 5 levels
- organ system or pharmacological classification (class A)
- therapeutic subgroup (class A10)
- pharmacological subgroup (class A10B)
- chemical subgroup (class A10BA)
- chemical substance (class A10BA02)
(see slides for deets)
4 main factors to psychopharmacology
Dose - response
Tolerance
Sensitivity
Withdrawal
Dose - reaction
§ How much do we need to give to get a certain response
§ Individual differences
Drug strength
There is a dose range of no effect, where increasing dosage means increased effects, and a maximum effect range
Tolerance
§ Repeated exposure
How does it change to adapt to drug
Sensitivity
As exposure goes up, sensitivity goes down (usually)
Withdrawal
§ With increased tolerance & dependence on a drug, the reduction of that drug typically causes an opposite effect to the drug itself
§ Withdrawal effects vary from drug to drug, and can last varying amounts of time
§ Internal systems perpetuate homeostasis by using counterregulatory methods to create a new state of balance based on the presence of the drug in the system
§ Adaptions include levels of NTS, hormones, and other substances to adjust for the addition of the drug to the body
Withdrawal means the body is no longer naturally producing the neurotransmitter it was before the drug use
NTs task: Number stages 1-5
1) NTs is synthesised in cell body or terminal
2) NTs is packaged into vesicle
3) NTs is released when vesicles fuse
4) NTs binds to and activates postsynaptic receptors
5) NTs is metabolised and transported back into terminal
Drugs: Agonists examples
- Benzodiazepine (activates GABA receptors)
- Morphine
- SSRIs (Indirect agonist)
- LSD
- THC
Drugs: Antagonist
Caffeine
Tolerance definition
the diminished response to drugs over the course of repeated or prolonged exposure
Accounted for by adapting physiological processes that achieve stability in a constantly changing environment (NIH, 2024)
Acute tolerance = reaction to initial surge of drug (short term effects - from 15-30 mins lessened)
Rapid tolerance = 24hrs for humans (4 for flies)
Chronic tolerance = repeated exposure over 24 hrs
Types of tolerance (4 types)
- acute
- pharmacodynamic
- pharmacokinetic
- behavioural
Acute tolerance
Tachyphylaxis!
Instant short-term effect of drug on NTs and synaptic junction
Pharmacodynamic tolerance
Dispositional!
Reduction in cellular response to drug (e.g. desensitisation of receptor, reduction in receptors)
Pharmacokinetic tolerance
Metabolic!
Absorption, distribution, metabolism and excretion of drugs (ADME)
= reduced amount of drug reaching site of action
(metabolism to drug - changes over time depending on how much drug consumed, sensitisation to drug changes)
Behavioural tolerance
Conditioned!
Tolerance to a behavioural effect of drug.
Occurs through drug-independent learning or as a form of pharmacodynamic tolerance in the brain
- learned effect to drug
- physiological effect - reward feeling associated with drug
Sensitivity
- drug intolerance▪ An increased response to a drug with repeated administration.▪ Amplified effects, including therapeutic benefits and side effects.▪ Mechanisms behind sensitization are not fully understood but thought to involve neuroadaptive changes.
▪ Understanding tolerance and sensitization is crucial for optimizing drug therapy as they impact dosing, effectiveness, and potential side effects
(see graph that shifts left when sensitised, and right when tolerance)
Withdrawal
With increased tolerance and dependence on a drug, the reduction of that drug typically causes an opposite effect to the drug itself. (vary from drug to drug)
Withdrawal means the body is no longer naturally producing the NTS it was before the drug use
▪ Internal systems perpetuate homeostasis by using counterregulatory methods to create a new state of balance based on the presence of the drug in the system.
▪ Adaptions include levels of neurotransmitters, hormones, and other substances to adjust for the addition of the drug to the body.
The release of what ions leads to the exocytosis of neurotransmitters from the terminal buttons?
calcium
What does an antagonist do?
Prevents storage of neurotransmitters in vesicles
On what receptors do psilocin work?
Serotonin
What type of tolerance is represented by a decrease in sensitivity of the receptor?
Pharmacodynamic
