EXAM 3 Drugs of abuse Dr. Pond Flashcards
What are the two forms of Dependence?
Physical dependence = dependence (withdrawal when stopping the drug)
Psychological dependence = addiction (compulsive, relapsing drug despite negative consequences, cravings
all addictive drugs produce a strong feeling of euphoria and reward
What are the forms of Tolerance?
reduced effect of drug over time
Pharmacokinetic tolerance: the drug is cleared faster
Pharmacodynamic tolerance: the body adapts to the drug (number of receptors is downregulated or less sensitive)
-sometimes both forms are seen
What do all addictive drugs have in common?
a strong feeling of euphoria and reward
activation of the dopamine-reward pathway in some way
-> Mesolimbic pathway
What is the Mesolimbic pathway
VTA (brainstem) -> Nucleus accumbens (limbic area)
other factors that activate this pathway: food, water, sex (surviving)
Which substances have the highest risk for addiction?
RR = 5
-Cocaine
-Amphetamine
RR = 4
-Nicotine
-Opioids
What are the enzymes involved in alcohol metabolism?
Alcohol dehydrogenase (ADH)
Ethanol -> Acetaldehyde
Aldehyde dehydrogenase (ALD)
Acetaldehyde -> Acetate
What kinetics does alcohol metabolism follow?
Zero-order kinetics
To which receptors does alcohol bind in the CNS?
-NMDA receptor - suppressing its activation
-GABA (A) activation (GABA(A) is inhibitory)
in total inhibitory
Other short-term effects of alcohol
-Vasodilator - severe overdose -> hypothermia
-Diuresis: inhibits antidiuretic hormone (ADH)
-sour stomach: stimulates gastric acid secretion
-decreased sexual function
-inhibits REM: although it causes sedation, it disrupts normal sleep pattern
Acute Tolerance of alcohol
reduced sensitivity of GABA(A) receptors
-> the first glass of wine has a greater effect than the last one
Chronic tolerance of alcohol
-metabolic tolerance: induction of microsomal enzymes (MEOS) -> second way to metabolize Ethanol to Acetaldehyde
-pharmacodynamic tolerance:
decreased sensitivity of GABA(A) receptors
downregulation of GABA(A) receptors in some parts of the brain
How does alcohol affect other drugs?
-additive or synergistic with other CNS depressants
-activation of MEOS -> build of toxic metabolites -> depletion of glutathione in liver cells -> acetaminophen toxicity
-increased risk of gastric bleeding when taking NSAIDs or aspirin
-cross-tolerance with other CNS depressants (fe benzos since the GABA(A) receptors become less sensitive)
What are the early withdrawal symptoms?
Rum fits
-nausea
-anxiety
-shakes
-sweating, cramps
-nightmares, hallucination
-tonic-clonic seizure (can be life-threatening)
What are the late withdrawal symptoms?
Delirium tremens
-confusion, disorientation
-agitation
-sweating
-hyperthermia
-cardiac collapse
What is the treatment for alcohol withdrawal?
Sedative hypnotics are common
-> usually benzos like diazepam -> then gradually taper off
-the goal is to prevent seizures
What are the long-term toxicities of alcohol?
-liver toxicity
-CNS dysfunction
-liver cirrhosis
-cardiomyopathy
-gastritis
-pancreatitis
-cancer risks
women at higher risk for HTN and the other toxicities
acute toxicities: nausea, vomiting, memory loss, passing out
What are the long-term effects on CNS function?
-increases ventricular size, decreases in
grey matter (brain scan)
-> cognitive impairment, memory loss,
anxiety, depression
What is the Wernicke-Korsakoff syndrome?
-paralysis of the eye muscle, ataxia, learning and memory deficit-> can progress to coma and death
-> lack of vitamin B1 (thiamine), malnutrition bc they get their calories from alcohol
-> loss of neurons in parts of basal forebrain