L4. Dose Response Flashcards Preview

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Flashcards in L4. Dose Response Deck (22)
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0
Q

Define Kd. What’s the formula?

A

Kd is the equilibrium dissociation constant. Kd = K1/K2 = EC50 (in ideal conditions).

1
Q

What is the difference b/t graded and quantal dose responses?

A

Graded dose responses occur as the dose amount increases so does the response.
Quantal dose responses are all or none responses.

2
Q

What makes a drug an agonist vs. an antagonist?

A

agonists have high dissociation constants and thus dissociate from the receptor quickly allowing more drug to bind and have a greater effect. Antagonists have a low dissociation constant and remain in the drug receptor complex for a longer time, blocking other drugs that could increase the drugs effect.

3
Q

Is a drug with a K3 of 1 an agonist or antagonist?

A

Agonist. Drugs with a K3 closer to 0 are antagonists.

4
Q

Define threshold dose and ceiling dose.

A

Threshold dose is the lowest dose that produces a response.

Ceiling dose is the lowest dose at which Emax is observed.

5
Q

If two drugs produce the same maximal effect (Emax) but one is more potent than the other (i.e. produces the same effect at a lower dose), is it a ‘better’ drug?

A

No. while the more potent drug may acheive the desired effect at a lower dose its side-affects may also be more potent and result in harsher negative affects at the lower dose than the less potent drug at its higher dose.

6
Q

While APAP (acetaminophen = tylenol), is less potent and has a lower Emax than the opioids codeine and oxycodone, why might APAP be used instead of, or in combo with low doses of, these opioids?

A

To avoid the nasty side affects of opioids. A single dose of opioids will cause ~60% of patients to feel side affects…very nasty drugs.

7
Q

What were the two changes to tylenol’s concentration that was intended to decrease the chance of liver failure due to acetaminophen overdose?

A
  1. Tylenol reduced the maximum daily dose of tylenol from 4,000 mg/day to 3,000 mg/day.
  2. All opioid-APAP combination drugs will no longer be allowed to contain greater than 325 mg acetaminophen per capsule.
8
Q

Name an opiate receptor agonist and antagonist.

A

Oxycodone is an opiate receptor agonist; K3 = 1.
Naloxone is an opiate receptor antagonist with a K3 of 0. Naloxone binds tightly to the opiate receptor binding sight while not activating the active sight.

9
Q

What is the major difference b/t competitive and non-competitive drugs?

A

Competitive drugs can reverse the affects of their counterparts
Non-competitive drugs can’t have their activities reversed

10
Q

Why is succinylcholine, a drug used to induce paralysis by blocking acetylcholine at the NMJ, potentially dangerous? What drug provides a safer alternative?

A

succinylcholine is a non-competitive inhibitor of ACH, thus if the patient does not have the required enzymes to degrade succinylcholine, paralysis may last for a long period of time. A safer alternative is Curare, which is a competitive binder to ACH, therefore to reverse paralysis all that is required is to increase [ACH].

11
Q

What receptor does ACH, curare, and succinylcholine bind to?

A

Nicotinic M cholinergic receptors

12
Q

What receptor do the agonists, ACH, muscarine & pilocarpine and the antagonists, atropine and scopolamine, act upon?

A

Muscarinic Cholinergic receptors

13
Q

What are the agonist and antagonistic affects upon muscarinic cholinergic receptors?

A

Agonist: Increased sweating and salivation. Decreased HR.
Antagonist: Decreased sweating and salivation. Increased HR.

14
Q

What receptor do the agonists, ACH and nicotine, and the antagonists, curare and succinylcholine, act on?

A

Nicotinic m cholinergic

15
Q

What receptor do the agonists, norepinephrine & epinephrine, and the antagonists , prazosin and phentolamine, act upon? Describe the affects of epinephrine and phentolamine and how they are used in dentistry.

A

Alpha-1 adrenergic receptors
Epinephrine causes vasoconstriction while phentolamine causes vasodilation. Phentolamine is used to dilute epinephrine at the site of an injection following a dental procedure to allow patient to recover from soft tissue numbness more quickly

16
Q

What are the agonistic and antagonistic effects on nicotinic m cholinergic receptors?

A

Agonist: Muscle stimulation (ex ACH)
Antagonist: Muscular paralysis (ex curare)

17
Q

What receptor does the agonist epinephrine and antagonists propanolol and metropolol act upon?

A

Beta-1 adrenergic

18
Q

What are the agonistic and antagonistic effects upon Beta-1 adrenergic receptor activation?

A

Agonist: Increased HR and contraction force

Antagonist (beta-blockers): Decreased HR and Contraction force

19
Q

Describe the difference b/t chemical and physiologic antagonism?

A

Chemical: Another molecule binds the substrate either inactivating it or blocking it from entering ion channels
Physiological: One substance does the exact opposite action but does so by binding a different receptor. Ex = Alcohol & caffeine.

20
Q

Tetracycline is knocked down when taken with milk. What type of antagonism is this an example of?

A

Chemical antagonism

21
Q

What conservative index is used to assess a drugs safety? How is it calculated?

A

Safety Index = LD 1/ED 99