Week 8: Psychopharmacology & addiction Flashcards
What is psychopharmacology?
The study of drug induced changes in mood, thinking and behaviour
In this case, study of the effects of drugs on the nervous system and therefore behaviour
What is a drug?
A drug is an EXOGENOUS CHEMICAL that is NOT necessary for NORMAL CELLULAR FUNCTIONING which alters the activity of certain cells in the body
What are psychoactive drugs used for?
- Altering mood
2. Treat psychopathology
What classifications of psychoactive drugs are used to alter mood?
Stimulants
Depressants
Hallucinogens
What are the drugs used to treat psychopharmacology and what are they specifically used for?
Anxiolytics: reduce anxious feelings
Antidepressant drugs: alleviate negative feeling that are associated with depression
Antipsychotic drugs: treat severe forms of psychotic behaviours (hallucinations and delusions)
What does pharmacokinetics mean?
The process by which drugs are absorbed, distributed within the body, metabolised and excreted
Drug effectiveness?
The ability of a drug to readily produce certain physiological and behavioural effects
Pharmacokinetics: What factors vary the effects of a drug?
- How/how often it is administered
- How rapidly it can enter the brain
- The context in which it is administered
- Our expectations of its effects
Drug absorption?
Refers to the mechanisms in which the drug gets into the bloodstream and is distributed throughout the body
What do drugs need to reach in order to be effective? and what do they need to do to get there?
Their site of action
- Need to access the blood system and cross the blood brain barrier
What has an influential effect on the rate at which this drug reaches its site of action
The route of administration
What have studies on differing routes of administration and cocaine shown?
Through intravenous routes of administration, blood plasma concentrations increase rapidly - within minutes we see maximal concentrations. HOWEVER, there rapidly decline and return to normal within 2 hours
For smoked, oral and intranasal administrations, we see a lower peak concentration of cocaine but the time taken to be eliminated from the blood is increased (trade off)
Explain ORAL administration?
- This is the preferred route of administration for many drugs
- Once swallowed, drugs dissolve in stomach fluids and are carried to the intestine where they are absorbed into the blood stream
- Some drugs pass through the stomach wall (alcohol) which means they take affect sooner
What are the advantages to ORAL administration of drugs?
Ease and relative safety
What are the disadvantages to ORAL administration?
There is a sense of unpredictability as it can be hard to gauge factors such as the amount and type of food in the stomach
Explain INJECTION administration
This is a common medical practice - injected drugs are strong, fast and predictable
Subcutaneously: into fatty tissue beneath skin
Intramuscularly: into large muscles
Intravenously: directly into veins
What route do those that are addicted to drugs prefer and why? Why is this a bad idea?
It is quick - straight into the bloodstream, straight to the brain.
The speed however, gives little opportunity to counteract the effects of an overdose, an impurity or allergic reactions
Explain the INHALATION route of administration
Some drugs can be absorbed into the bloodstream through the rich network of capillaries in the lungs (tobacco, marijuana)
What are some disadvantages to the INHALATION route of administration?
It is difficult to precisely regulate the dose of inhaled drugs
Substances can damage the lungs if they are inhaled chronically
What is the blood-brain barrier?
The brain has developed this barrier in order to protect itself against dangerous molecules that may damage the brain tissue
How do molecules enter pass through the BBB
Often active transport is used
Only a barrier for water molecules- those that are soluble in lipids pass through the cells that line the capillaries of the CNS
How do endothelial cells facilitate or hinder the movement of molecules across the BBB
Passive movement of water-soluble agents across the BBB is negligible because of the tight junctions between endothelial cells.
Small, lipid-soluble agents, such as antidepressants, cross the BBB via diffusion through endothelial cell