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Week 3: Pharmacology > Pharmacodynamics > Flashcards

Pharmacodynamics Flashcards

1
Q

Drug Target

A

Almost all drug targets are proteins.

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2
Q

Agonist

A

Drugs that mimic the effects of the endogenous agonists.

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3
Q

Antagonist

A

Drugs that block the effects of endogenous agonists.

  • Concentration-Dependent
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4
Q

Dose-Response Curve

A

The graph that shows the relationship between ligand (drug) concentration and receptor occupany.

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5
Q

Kd (dissociation constant)

A

The concentration of drug when 50% of receptors are occupied.

*As Kd decreases, affinity of drug for receptor increases.

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6
Q

Hill-Langmuir Equation

A

Y= D/Kd+D

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7
Q

Drug Potency

A

How tightly a drug binds to a receptor. Also can be interpreted as “Receptor Occupancy.”

Lower Kd (lower drug concentration to occupy 50% of receptors).

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8
Q

Drug Efficacy

A

Therapeutic Effect of a drug.

Drugs with different Kd can still achieve the same efficacy (may not always be 100%).

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9
Q

Receptor Occupancy on Y-axis

A

Kd can only be read when Y-axis is “receptor occupancy.”

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10
Q

Receptor Reserve

A

Extra/Leftover receptors that are available for agonist binding, but they are not needed to produce a maximal effect.

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11
Q

Competitive Antagonist

A

Binds at the same site as agonist. REVERSIBLE

  • Shifts the dose-response curve to RIGHT
  • Decreases potency (increase in Kd)
  • Can be overcome by adding more agonists
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12
Q

Reversible Non-Competitive Antagonist

A

Binds at the allosteric site of receptor.

  • Brings the dose-response curve DOWN
  • Decreases efficacy (negligible increase in Kd)
  • Cannot be overcome by adding more agonists
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13
Q

IRREVERSIBLE Non-Competitive Antagonist

A

Binds at the same site as agonist but LOCKS the receptor.

  • Brings the dose-response curve DOWN
  • Decreases efficacy (negligible increase in Kd)
  • Cannot be overcome by adding more agonists
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14
Q

Full Agonist

A

An endogenous molecule or a drug that produces the max. effect.

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15
Q

Partial Agonist

A

A drug that produces the sub-maximal effect.

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16
Q

Neutral Antagonist

A

Many drugs that reduce the effect of an agonist but has no effect itself.

  • Competitive and Non-competitive antagonists
17
Q

Inverse Agonist

A

A drug that Inhibits the BASAL activity of a receptor when normal agonist is NOT PRESENT.

  • When the normal agonist is present, they also act as a competitive antagonist.
18
Q

Dose-Response Curve For Quantal Response

A

For quantal responses, the dose-response curve is the cumulative % of patients responding (exhibiting the therapeutic effect).

19
Q

Therapeutic Window

A

The range of minimum effective/therapeutic dose and minimum toxic dose.

20
Q

Therapeutic Index (TI)

A

TD50/ED50 or LD50/ED50

  • Higher the better safety wise.
  • TILE
  • Measured at 50% of cumulative % responding
21
Q

Mechanism-Based Toxicity

A

aka. on-target toxicity

* both therapeutic and toxic target is the SAME.

22
Q

Off-Target Toxicity

A

Therapeutic and toxic effects targeting different receptors.

23
Q

Certain Safety Factor (CSF)

A

LD1/ED99

  • Higher the better safety wise.
  • Better measurement for Off-Target Toxicity graphs
24
Q

Combining Two Drugs with Same Therapeutic Effect

A
  • Additive: result is same as taking them together independently.
  • Synergistic: Combining produces a larger effect than expected.
  • Antagonistic: Combining produces a smaller effect than expected, but still better than taking just either one.
25
Q

Potentiation

A

When one drug has a therapeutic effect, and a second drug helps it (no effect of its own).

26
Q

Cephalosporin vs. Probenecid

A

Probenecid (has no own effect) potentiates the effect of cephalosporin by inhibiting renal clearance, and therefore increase drug’s serum concentration and therapeutic effect.

27
Q

Tachyphylaxis

A

aka. tolerance/desensitization

Reduced effect with prolonged use of a drug.

28
Q

3 Mechanisms of Tachyphylaxis

A
  1. Receptor Inactivation
  2. Receptor Internalization
  3. Receptor Down-Regulation
29
Q

Receptor Internalization

A

The process that results in the endocytotic movement of receptors from the plasma membrane to the inside of the cell.

30
Q

Receptor Down-Regulation

A

A decrease in the number of receptors (due to lysosomal degradation) on the surface of target cells, making the cells less sensitive to a drug.

31
Q

Receptor Inactivation

A

Desensitized receptor which is unable to signal cascade.

32
Q

MOR (u-opioid receptor)

A
  • Naloxone
  • Naltrexone

Inverse Agonist for opioid overdose

Week 3: Pharmacology (2 decks)

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