PHARM - Drugs of Abuse - Week 9 Flashcards
Why does dependence to drugs occur?
Progressive pharmacological adaptation to the drug, resulting in tolerance
What happens to homeostasis in response to repeated drug exposure? What is a consequence of this?
It is reset. An individual in this state needs continuous drug administration to maintain normal function.
If there is a dependence on drugs, what happens if the drug is abruptly stopped?
Withdrawal symptoms occur
Define abstinence.
Practice of not doing something or having something that is wanted or enjoyable
Define psychological dependence, including the physiological basis for it, and what normally happens in individuals with no dependence.
Also called addiction - administration of substances or certain behaviours activate brain reward circuits.
These motivate normal behaviour which most people enjoy without being compelled to repeat them.
What occurs with reflexice acivation of reward circuits?
It becomes involuntary, drawing a person into compulsive repetition and putting focus on the immediate pleasure despite negative consequences.
Where is the primary action of drugs of abuse?
In the CNS - the brain reward circuits
What system specifically do addictive drugs activate? What consequence does this result in?
The mesolimbic dopamine system, producing a rewarding-reinforcing action.
What effect does alcohol have on the CNS?
Depressant
What neurotransmitter does alcohol bind to and increases transmission of what neurotransmitter?
Binds to GABA and increases GABA-ergic transmission
What two neurotransmitter receptors are altered by alcohol?
NMDA and 5-HT3 (serotonin)
Is alcohol rapidly or slowly absorbed and distributed?
Rapid
Describe how alcohol is processed by the body in terms of percentages (5).
90% is oxidised in the liver
The rest is eliminated via saliva, sweat, breath, and urine
Can an overdose of alcohol be fatal? Explain why.
Yes, due to the effects of being a depressant and acetaldehyde (a metabolite)
After what time period following cessation of heavy drinking does the dependence on alcohol become apparent?
6-12 hours
Name 5 withdrawal symptoms of alcohol after 6-12 hours.
Hand tremors Nausea Excessive sweating Agitation Anxiety
Name a withdrawal symptom of alcohol after 12-24 hours (1).
In some individuals, visual/tactile/auditory hallucinations may occur
Name a withdrawal symptom of alcohol after 24-48 hours (1).
In some individuals, siezures may occur
Name a withdrawal symptom of alcohol after 48-72 hours. What percentage of mortality is it associated with?
Delirium - 5-15% mortality
What is the standard first-line treatment for acute alcohol withdrawal symptoms?
Benzodiazepines
What is naltrexone and what does it prevent? How long is its action?
An opioid receptor antagonist
Prevents euphoria
Long action - 24-72h
How does naltrexone work (2)?
Blocks action of the endogenous opioids released by alcohol
Blocks activation of dopamine reward pathways
What overall effect will naltrexone have (2)?
Decreases pleasurable effects linked to alcohol consumption
Reduces cravings
Name 4 common adverse effects and one serious but rare adverse effect of naltrexone.
Insomnia Headache Fatigue Dizziness Hepatotoxicity
What must be monitored during naltrexone therapy?
Liver function
What does disulphiram promote?
Abstinence in motivated alcoholics after initial detoxification
What is disulphiram?
Aldehyde dehydrogenase inhibitor
How does disulphiram work (2)?
Blocks degradation of acetaldehyde to acetate
Acetaldehyde accumulates in the body and casues unpleasant symptoms
Name 7 symptoms of disulphiram and a reason why if applicable.
Intense flushing Headache (throbbing) Sweating The above are caused due to acetaldehyde being a potent vasodilator Nausea Vomiting BP changes Hyperventilation
When is acamprosate used?
Maintenance of abstinence in alcohol dependence
What effect does acamprosate have on the CNS (2)?
Restores normal activity in glutamate and GABA systems.
How long does acamprosate therapy last?
Up to a year
What should be checked before acamprosate therapy?
Creatinine levels
Name 3 side effects of acamprosate.
Rash
Diarrhoea
Changes in libido
What addiction exceeds all others?
Nicotine addiction