18. Drug Addiction Flashcards
What is substance abuse?
Pattern of harmful use of a substance for mood-altering purposes
What is tolerance defined as?
Either:
Need increased amounts to achieve desired effect
or
decreased effect from using the same amount of the substance
What is withdrawal defined as?
Either:
Characteristic set of symptoms for that substance
or
Substance is taken to relieve or avoid withdrawal symptoms
What are the types of tolerance?
Innate Pharmacokinetic Pharmacodynamic Conditioned Acute Reverse Cross-tolerance
What is the difference between innate and conditioned tolerance?
Innate is a genetic lack of sensitivity eg. codeine and CYP2D
Conditioned is an adaptation to environmental cues eg. smell of the drug increases tolerance
What is the difference between pharmacokinetic and pharmacodynamic tolerance?
Kinetic= change in metabolism of the drug eg. barbituates Dynamic= change in receptor activity
What is physical dependence?
Drug specific withdrawal symptoms are produced by a sudden stop or decrease in amount of drug, or administering an antagonist
What is a Dependence Syndrome?
Need drug to maintain normal function
What pathway is targeted by drugs of abuse?
Mesolimbic dopaminergic pathway
- from ventral tegmental area in midbrain
- to nucleus accumbens in forebrain
What pathways are activated by nicotine?
Dopamine reward pathway
Central nicotinic receptors
Peripheral nicotinic receptors
What effect does nicotine have at central nicotinic receptors?
Anxiolytic
Suppresses appetite
What effect does nicotine have at peripheral nicotinic receptors?
Increase BP
Smooth muscle contraction
Why is it said that ‘the first cigarette is the best one’ and what effect does this mechanism have long term?
Nicotinic receptors have a ‘rapid switch off’ after initial stimulation
Over time there is a compensatory upregulation of nAChR
What are the withdrawal symptoms of nicotine?
Lightheaded, waking up at night
Poor concentration, irritability, depression, restlessness
Craving and increased appetite
What are the behavioural treatments for nicotine withdrawal?
CBT
Motivational interviewing
Mindfulness
What is the pharmacological treatment for nicotine withdrawal?
Nicotine replacement therapy
Bupoprion (increase dopamine)
Varenicline (partial agonist of nicotine receptor)
What compound is the addictive component of cannabinoids?
THC
How does cannabis lead of increased release of dopamine?
Cannabinoid receptors decrease GABA release
What is the MOA of cocaine?
Blocks DAT and VMAT transporters
-stops reuptake of dopamine, NA and serotonin
What is the MOA of amphetamines?
Block DAT
What are the signs of an overdose of psychostimulants?
Increase temperature, HR and BP
Heart failure, seizure, respiratory depression
What is the treatment for an overdose of psychostimulants?
Benzodiazepines
Ca++ channel blockers to decrease BP
What are the symptoms of a psychostimulant withdrawal?
Difficulty concentrating
Restlessness
Depression and anxiety
What is the treatment for psychostimulant withdrawal?
Propanolol for high BP
Disulphiram
