Therapeutic drugs, pt. 2
1) First, watch these videos:
ADHD medications
Anti-anxiety medications
Opioid-related drugs
2) Next, answer these questions to test your understanding:
1. Methadone is often used to treat opioid addiction. Its action at the opioid receptor is as a/an:
- A. antagonist (blocks receptor activity)
- B. full agonist (fully activates the receptor)
- C. partial agonist (activates the receptor but with less effect than full agonist)
- D. inverse agonist (produces opposite effect of receptor activation)
Show Answer
Correct answer: B
Methadone is a full agonist at μ-opioid receptors (similar to other opioids). Taken orally, it has a slow onset and long half-life, providing steady effects that reduce withdrawal and cravings while also avoiding injection-related risks like blood-borne infections.
2. Which of the following best describes the primary mechanism of action of methylphenidate in the brain?
- A. inhibition of voltage-gated potassium channels
- B. stimulation of serotonin synthesis
- C. inhibition of dopamine and norepinephrine reuptake
- D. blockade of postsynaptic dopamine receptors
Show Answer
Correct answer: C
Methylphenidate is a stimulant drug. Its primary mechanism of action is thought to be the inhibition of reuptake of the neurotransmitters dopamine and norepinephrine. Reuptake is a process used by neurons to remove excess neurotransmitters from the synaptic cleft. In reuptake, proteins called transport proteins move neurotransmitters out of the synaptic cleft and typically back into the neuron that released them. Thus, by inhibiting reuptake, methylphenidate increases levels of dopamine and norepinephrine in the synaptic cleft. These elevated levels of dopamine and norepinephrine lead to increased activity at the receptors for these neurotransmitters, and cause various alterations in brain activity.
3. The pharmacological mechanism of beta blockers in treating performance anxiety involves antagonism of receptors for which of the following:
- A. serotonin
- B. norepinephrine
- C. dopamine
- D. cortisol
Show Answer
Correct answer: B
Beta blockers are antagonists at receptors called beta-adrenergic receptors, meaning they block these receptors. Beta-adrenergic receptors are normally activated by epinephrine and norepinephrine, and their activation increases heart rate and blood pressure (among other effects). Thus, by blocking beta-adrenergic receptors, beta-blockers can decrease heart rate and blood pressure and help to decrease physical symptoms of anxiety.
4. Naloxone (Narcan) is a drug that can be administered to treat and potentially reverse the effects of an opioid overdose. It works by blocking opioid receptors (the receptors opioid drugs bind to), as well as by displacing opioid drugs that are already attached to the receptor. Naloxone's mechanism of action is best described as:
- A. antagonism
- B. agonism
- C. allosteric modulation
- D. inverse agonism
Show Answer
Correct answer: A
Naloxone is a competitive antagonist at opioid receptors, which means that it works by binding to the same receptors that opioid drugs bind to, but instead of activating those receptors like opioid drugs, naloxone blocks activity at them. Naloxone also causes opioid drugs that are already attached to the receptor to be displaced.
5. Benzodiazepines bind to GABA receptors at a location separate from where GABA binds. They don't cause activation of the receptor on their own, but they enhance the effect of GABA when it binds to the receptor. What is the name for this type of drug action?
- A. allosteric modulation
- B. agonism
- C. antagonism
- D. inverse agonism
Show Answer
Correct answer: A
Drugs that bind to a receptor at a different site from where an agonist binds and influence the function of the receptor are called allosteric modulators. Allosteric modulators may increase or decrease the likelihood of an agonist binding to a receptor, enhance or reduce the effects an agonist has when it does bind, or activate the receptor on their own.
