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Lex Clinical Pharm exam 1 > 2. Agonists/Antagonists > Flashcards

2. Agonists/Antagonists Flashcards

1
Q

Agonist

A

Promote normal cell signaling process by mimicking natural chemical and enhance cellular activity

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2
Q

Antagonists

A

Most drugs

Interact at same site as natural chemical and inhibits signaling pathway

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3
Q

Agonists Actions

A

Activates receptors in physiological systems so the drug mimics physiological activation

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4
Q

Epinephrine

A

Agonist

Activates beta receptors in the heart causing increase in HR and force contractions

Also has an affinity for alpha receptors in the SNS causing vasoconstriction in large arterial smooth muscle resulting in increase BP

Epi - non-selective effect on SNS alpha and beta receptors

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5
Q

Antagonist actions

A

Block receptors or enzymes in physiological systems

Drug effects are in the OPPOSITE direction of normal physiological response

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6
Q

Metoprolol

A

Beta receptor antagonist in SNS so effects are decrease HR

Does not allow norepinephrine to bind at its normal receptor

Norepinephrine normally causes increase HR

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7
Q

Atropine

A

Acetylcholine antagonist - inhibiting an inhibitory process

Will bump acetylcholine off acetylcholine receptors that normally do not let signal proceed- decrease HR

Through bumping them off signaling pathway continues:

Cause Increase HR

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8
Q

Benzodiazepines

A

GABA agonist

More neuron inhibition

Feel relaxed and sleepy

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9
Q

Flumazeneil

A

Used for benzodiazepine overdose

GABA Antagonist - does not let chloride enter the cell, therefore nerve fires and wakes people up

Net effect: increase neuron firing, wakes people up

Can cause seizures

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10
Q

Antagonist Actions not always “net negative effect”

A

Some physiological systems when activated results in a decrease in end organ effects

Antagonist to an inhibitory process: Inhibiting an inhibitory process causes other processes to up regulate -increase HR

Ex: in PNS acetylcholine is naturally occurring agonist

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11
Q

Atropine is an acetylcholine antagonist so it would cause:

A

Acetylcholine is a naturally occurring agonist-inhibit signaling pathways in heart leading to decrease HR

So atropine is Inhibiting an inhibitory process to up regulate other processes

Increase HR

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12
Q

GABA Receptors in the Brain

A

Inhibitory signaling pathway - when receptors are activated they inhibit signaling processes

When enzyme binds to GABA receptors causes hyperpolarization - more Cl- into the cell and inhibiting nerve from firing (net negative nerve firing)

Ex: alcohol, benzodiazepines (agonist with net negative effect)

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13
Q

Enzyme Inhibition

A

Drug that binds to enzyme site and prevents physiologic process

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14
Q

Angiotensin

A

NORMAL :Substrate binds to Angiotensin Converting enzyme to convert angiotensin I to angiotensin II

DRUG: Lisinopril - binds to angiotensin converting enzyme in the same was angiotensin I would bind, preventing angiotensin I from binding and now Angiotensin I is not converted to Angiotensin II- lower BP

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15
Q

Non-Competitve Inhibiton

A

target site on enzyme that changes conformation of enzyme and now less likely substrate will want to bind

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16
Q

Competitive Inhibiton

A

Lisinopril example with Angiotensin

Interferes with active site so substrate cannot bind

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17
Q

Stereochemistry

A

Orientation of drugs and how they fit into receptor site determines how likely they will bind- usually 50/50 mixture

S-Left side
R-Right

S-Omeprizol = one enantiomer more effective/potent

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18
Q

Full agonist

A

The more drug you give the greater the effect until you reach a plateau - full effect

Narcotics = more drug higher response

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19
Q

Partial Agonist

A

Interact at same receptor site as full agonists, but do not give same effect as other medications in that class would even as drug concentration increases

Buprinorphine - used to treat pain, causes decreased effect (saboxone) used to treat opioid addiction. If people take it they do not get same high as oxycodone (full agonist)

Mg-mg of full and partial agonists the effects are much less in partial agonists

Can stay at receptor and prevents other opioids from binding

20
Q

Sensitization or Up-Regulation of Receptors

A
  1. Prolonged or continued use of receptor antagonist

More receptors pop up on cell and increase receptors for natural compounds/medication

  1. Can develop over months to a year
21
Q

Desensitization or Down-regulation of Receptors

A
  1. Prolonged or continuous use of receptor agonist

Receptors become internalized because of the prolonged stimulation

“Medication not working well anymore”

2 can develop over months to a year

22
Q

Drug Tolerance

A

Risk of tolerance depends on drug, potency, dose, chronicity of use, individual variability and physiological system involved

23
Q

Drug Tolerance in Agonists

A

Prolonged use of agonists leading to a down-regulation of receptors result in a DECREASED effect of the agonist drug at the chronic dose

24
Q

Drug tolerance in Antagonists

A

Prolonged use of antagonists leading to up-regulation of receptors result in DECREASED effect of the antagonist drug at the chronic dose

25
Q

Cross-Tolerance

A

Occurs with drugs that affect similar receptors

EX: benzo and alcohol bind to same receptors so it benzos have decrease effect

26
Q

Drug Withdrawal

A

Abrupt cessation of drugs to which tolerance has developed

Withdrawal effects are the opposite of the original effects of the drug in the system due to receptor adaptation (down/up regulation)

Different from addiction - addiction is seeking the drug based on euphoric feeling

Not all tolerance = addiction, tolerance occurs over months addiction usually faster

27
Q

Withdrawal after down regulation (agonist)

A

Benzodiazepine on GABA receptor in brain:

Benzodiazepine is overstimulating the receptors so some will become internalized and the patient does not get same relaxed feeling and has other regulatory molecules dominating exciting other neurons

Causes: anxious feelings

28
Q

Withdrawal after up regulation (antagonist)

A

NORMALLY: Metoprolol wants to lower HR - binds to beta-receptors on heart blocking epinephrine from binding - inhibiting physiological pathway

After time body does not like HR being that low and will up regulate more receptors and now more places for epinephrine to bind and allow physiological process to move forward and HR increases

29
Q

Drug Dose-Response Relationships

A

Drug response is logarithmic so as you increase the dose it effects will eventually plateau - there are only so many receptors for drug to bind

increasing dose will not increase efficacy could cause adverse side effects and toxicity

30
Q

Therapeutic Effects

A

Pharmacological effect of drugs used to treat disease state

31
Q

Side effects

A

Pharmacological effects other than intended to treat disease

EX: dihareia from metformin

32
Q

Adverse Drug Reactions

A

Side effects significant enough to warrant a change in dose or discontinuation of medication

Lisinopril - constant cough

33
Q

Toxic Effects

A

Predicative side effects that are severe and indicative of too high a dose or concentration of the dug

Narcotics- stop breathing

34
Q

Idiosyncratic Side effecrs

A

Generally unpredictable, non-dose related and related to an immune system response

EX: skin rash, anaphylaxis

Hydralazine (antihypertensive medication) causing Lupus

Solution: discontinue medication and document as an allergy

35
Q

What determines drug dose?

A

Looking to optimize the effect based on 50% of targets bound

Balancing efficacy and side effecrs

Drugs lose selectivity at higher concentrations

More drug acting at different sites cause unintended side effects

36
Q

Potency

A

Used to describe concentration of the drug (in relation to other drugs or the endogenous conmpound) to achieve the same effect

Higher the potency = lower the drug dose

Potency is influenced by molecular chemistry and bond interactions

37
Q

Therapeutic Indec

A

Drug Safety!

TI = 50% therapeutic effect/ 50% toxic effect

Large TI= monitor less frequently, safer

Small TI= monitor more frequently

38
Q

Drug-Drug Interactions

A

Effects of two drugs or more that increase or decrease the actions of one or another

39
Q

Pharmacokinetics Drug-drug Interactions

A

One drug inhibits the breakdown of another medication

More common

40
Q

Pharmacodynamic Drug-drug interactions

A

Stimulate same receptors

Ex: benzo and alcohol

Ace inhibitor
Alpha blocker = net benefit of decreasing BP, but do not work on same mechanism

41
Q

Additive effects of drugs

A

(1+1=2)

Give 2 blood pressure lowering medications

42
Q

Synergistic Effects of Drugs

A

(1+1=4)

more pronounced effect from medication

2 antibiotics that work together - more drug killing when given together than if were given individually

43
Q

Drugs that antagonize each other

A

Some medications when given together cause effects that mitigate each other or decrease effectiveness of other drugs

Pharmacodynamics response, not at the same receptor- multiple signaling molecules or receptor cause the same physiologic response

44
Q

Pseudoephedrine and patients taking BP lowering medications

A

Drugs that antagonize each other

pseudoephedrine - increases BP and HR

With patients taking BP lowering medication who take pseudoephedrine their BP and HR will increase

45
Q

Causes of variability in Drug Response

A
  1. Body weight and size
  2. Age and sex
  3. Genetics- pharmacogeneitics
  4. Conditions of health
  5. Placebo effect
46
Q

Causes of variability in drug response (pharmacokinetics)

A
  1. Dose formulation, route of administration
  2. Drug tolerance from repeated administration
  3. Drug interactions

Lex Clinical Pharm exam 1 (14 decks)

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