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10# Drugs of Abuse
1. Drug abuse is BEST defined as:
Any use of prescription drugs
Use of drugs leading to tolerance only
Intentional, excessive, or harmful use for non-medical purposes
Use associated only with physical dependence
Explanation:
Drug abuse refers to intentional, harmful, non-therapeutic use with risk of addiction and dysfunction.
2. Tolerance is best described as:
Development of withdrawal symptoms
Decreased effect requiring higher doses for same response
Psychological craving
Loss of behavioral control
Explanation:
Tolerance means reduced response to a drug after repeated use.
3. Which feature is NOT required for the diagnosis of addiction?
Craving
Loss of control
Continued use despite harm
Tolerance and withdrawal
Explanation:
Tolerance and withdrawal are common but NOT required for addiction diagnosis.
4. Cross-tolerance occurs when:
Tolerance to one drug reduces response to another with similar mechanism
Two drugs are taken simultaneously
Withdrawal symptoms worsen
Psychological dependence develops
Explanation:
Example: tolerance to morphine causes tolerance to fentanyl (both μ-agonists).
5. The mesolimbic dopamine pathway is MOST responsible for:
Motor control
Reward and reinforcement
Prolactin regulation
Pain modulation
Explanation:
Addiction is mediated by dopamine release in the mesolimbic pathway.
6. Caffeine produces CNS stimulation mainly by:
Activating GABA receptors
Blocking sodium channels
Blocking adenosine receptors
Inhibiting MAO
Explanation:
Adenosine inhibition leads to increased alertness and tachycardia.
7. Which effect is MOST likely at very high caffeine doses?
Sedation
Bradycardia
Hypotension
Convulsions
Explanation:
Toxic caffeine doses can cause spinal cord stimulation and seizures.
8. Caffeine should be avoided in patients with:
Peptic ulcer disease
Asthma
Hypothyroidism
Anemia
Explanation:
Caffeine increases gastric acid secretion and worsens PUD.
9. Caffeine withdrawal typically presents with:
Seizures
Headache and fatigue
Psychosis
Severe autonomic instability
Explanation:
Withdrawal symptoms last a few days to one week.
10. Nicotine causes addiction mainly by:
Blocking muscarinic receptors
Inhibiting MAO
Stimulating neuronal nicotinic receptors → dopamine release
Activating GABA neurons
Explanation:
Dopamine release in reward pathways causes nicotine dependence.
11. At toxic doses, nicotine causes:
Pure stimulation only
Selective CNS depression
Bradycardia without paralysis
Ganglionic blockade and respiratory paralysis
Explanation:
High doses cause depolarization blockade of nicotinic receptors.
12. Nicotine is a liver enzyme inducer, therefore it:
Reduces levels of some co-administered drugs
Inhibits drug metabolism
Prevents withdrawal symptoms
Has no drug interactions
Explanation:
Enzyme induction increases metabolism of other drugs.
13. Cocaine causes euphoria primarily by:
Stimulating opioid receptors
Blocking GABA receptors
Blocking dopamine reuptake
Inhibiting acetylcholinesterase
Explanation:
Dopamine accumulation in synapses produces intense euphoria.
14. Nasal septum perforation in cocaine users occurs due to:
Immune suppression
Local vasoconstriction and tissue ischemia
Infection alone
Hypersensitivity reactions
Explanation:
Vasoconstriction and chemical irritation cause cartilage damage.
15. Cocaine overdose most commonly leads to death due to:
Renal failure
Liver failure
Hypoglycemia
Respiratory failure and seizures
Explanation:
Severe CNS stimulation leads to seizures and respiratory arrest.
16. Amphetamines differ from cocaine because amphetamines:
Increase neurotransmitter release
Only block reuptake
Have no therapeutic uses
Do not cause tolerance
Explanation:
Amphetamines increase release of dopamine, NE, and serotonin.
17. The antidote for amphetamine overdose is:
Naloxone
Flumazenil
Haloperidol
Atropine
Explanation:
Haloperidol blocks dopamine-mediated toxicity.
18. Amphetamine withdrawal is characterized mainly by:
Severe autonomic instability
Psychological depression and fatigue
Seizures
Hallucinations only
Explanation:
Withdrawal is predominantly psychological.
19. Which amphetamine derivative is associated with severe tooth decay?
Methylphenidate
Modafinil
Dextroamphetamine
Methamphetamine
Explanation:
Methamphetamine causes “meth mouth”.
20. Fenethylline (Captagon®) is best described as:
A prodrug metabolized into amphetamine and theophylline
A pure opioid agonist
A benzodiazepine
A cocaine derivative
Explanation:
Illicit Captagon has variable composition and high addiction risk.