Drugs of abuse Flashcards
What are 5 characteristics of the drug dependance syndrome?
- desire or sense of compulsion to take the substance.
- difficulty in controlling use.
- physical withdrawal state.
- progressive neglect of other interests, increasing time obtaining and taking substance.
- persistence with substance regardless of detrimental effect. Be it cognitive, physical or social.
Meso-limbic dopamine pathway is involved in what?
Brain reward pathway.
Where are the cell bodies of the meso-limbic pathway and where do the neurons terminate?
Cell bodies in VTA, ventral tegmental area and neurons terminate in the nucleus accumbens.
Many drugs increase dopamine release where?
Shell of the nucleus accumbens.
Give one example of a drug which enhances serotonin and one which is a hallucinogenic NMDA antagonist.
MDMA and ketamine.
What are the functions of the dopamine pathways?
Reward (motivation). Pleasure, euphoria. Motor function (fine tuning). Compulsion. Perserveration.
What are the functions of the serotonin pathways?
Mood.
Memory processing.
Sleep.
Cognition.
Opiates are agonists where? What effect does this have?
G-protein coupled opioid receptors, reduces neurotransmitter release in brain and periphery.
What are the acute effects of opiates?
Euphoria, tranquility, miosis, drowsiness, itching and nausea.
What are the chronic effects of opiates?
Anhedonia, depression, constipation, insomnia, dependance.
What symptoms are seen when withdrawal precipitates?
Restlessness, muscle and bone pain, insomnia, diarrhoea, cold flashes with goose bumps (cold turkey) and vomiting.
When do major withdrawal symptoms peak?
24-72hrs after last dose.
Cocaine acts as what by blocking Na+ channels?
Anaesthetic.
What are the effects of cocaine?
Euphoria and excitement, increased capacity for work.
In high doses what does cocaine cause?
Overactivity of the sympathetic nervous system - tachycardia, hypertension, hyperpyrexia, dilated pupil, palpitations.
Is there tolerance with cocaine?
No.
What dependance occurs with cocaine and what dependance doesn’t?
Physical dependance does not occur but psychological dependance does.
Amphetamines produce what effect?
Increased wakefulness and concentration in association with decreased fatigue and appetite. Performance enhancing.
Psychological effects include?
Euphoria, increased libido, energy, self-esteem, self-confidence, aggression, excessive feelings of power.
When can amphetamine psychosis occur?
In chronic and high doses.
Ecstasy acts as what?
Stimulant and psychedelic.
In high doses MDMA can interfere with what?
Temperature regulation.
When is MDMA neurotoxic?
Following systemic but not central administration.
What does THC mimic?
The effects of small endogenous lipid messengers.
Inhibits wide range of neurotransmitter release in the brain and periphery how?
Via G-protein coupled cannabbinoid receptors.
What effect do you get in mild and high doses?
Mild can be euphoric, high is dysphoric.
What other effects does it have?
Stimulates appetite by stimulating feeding centres in the hypothalamus and possibly the gut. Analgesic.
What effects does alcohol have?
CNS depressant, in large doses irritates the stomach, inhibits ADH which leads to dehydration (hangover).
What does long term drinking lead to?
Neuropathies eg: Wernicke’s encephalopathy (psychosis). Hepatotoxicities and haematological disorders.
What relevance does methadone have in treatment for opiate abuse?
It is a long acting synthetic opiate agonist. Blocks effects of illicit opiate use and decreases opiate craving.
Name two other antagonist drugs used to help in abuse
Naltrexone - therapy for opiate addiction.
Mecamylamine - nicotinic acetylcholine receptor antagonist. Blocks rewarding actions of nicotine and cue-induced craving.
What is the anti-craving medicine used for alcohol abuse?
Acamprosate - reduces neuronal excitability that occurs during alcohol withdrawal. Naltrexone is also used in alcohol withdrawal. It interferes with positive reinforcement and possibly alcohol-conditioned cues.
