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Pharmacology Test 4 > DDI > Flashcards

DDI Flashcards

1
Q

What is clearance?

A

A quantitative measure of the rate at which a substance is removed from the blood, ie, by the kidneys, the liver, or hemodialysis; the volume of plasma cleared per unit time.

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2
Q

What is a narrow therapeutic index?

A

Drugs for which small changes in systemic concentration can lead to significant changes in pharmacodynamics response.

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3
Q

What is pharmacodynamics?

A

the biochemical and physiological effects of drugs and the mechanisms of their actions, including the correlation of their actions and effects with their chemical structure.

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4
Q

What is pharmacokinetics?

A

The action of drugs in the body over a period of time, including the processes of absorption, distribution, localization in tissues, biotransformation, and excretion.

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5
Q

What is a drug interaction?

A

An adverse drug response produced by the administration of a drug or co-exposure of the drug with another substance.
Modifies a patient’s response.
Some are intended to improve therapeutic response or decrease adverse effects.

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6
Q

Which drug is the precipitant drug?

A

The drug, chemical, or food causing the interaction.

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7
Q

What is the object drug?

A

the drug affected by the interaction.

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8
Q

What is a pharmacokinetic drug interaction?

A

When ADME is changed by another drug, chemical, or food element.

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9
Q

What is a pharmacodynamic drug interaction?

A

When the effect of the drug is altered by another drug, chemical, or food element, producing an antagonistic, synergistic, or additive effect.

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10
Q

What is a pharmaceutical drug interaction?

A

incompatibilities when drugs are mixed, ie, making IVs

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11
Q

PK interactions may affect?

A

Absorption
Distribution
Drug elimination and clearance

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12
Q

PD interactions may affect:

A

Drugs with similar actions produce excessive or toxic responses.
The effect of one drug may be antagonized by the opposite effect of another.
An adverse effect of one drug may increase the sensitivity or toxicity of another.
Drugs with opposite effects on the same target may cause therapeutic failure.

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13
Q

How can drug interactions be affected by absorption?

A 
Complexation, chelation
adsorption
Increased GI motility
Decreased GI motility
Alteration of gastric pH
Alteration of intestinal flora
Inhibition of drug metabolism in intestinal cells
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14
Q

What additional interactions may affect bioavailability from GI tract?

A

Competition from carrier-mediated drug absorption where precipitant drug competes for same carrier as object drug.
Alteration in intestinal blood flow caused by precipitant drug.

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15
Q

How can distribution be affected?

A

plasma protein binding

competition

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16
Q

What is an example of plasma protein binding competition?

A

valproic acid displaces phenytoin

Aspirin decrease valproic acid protein binding

17
Q

What is an example of a drug that is affected by tissue and cellular interactions?

A

Digoxin toxicity can be enhanced by concurrent administration of quinidine

18
Q

Metabolism and clearance may be affected by:

A

enzyme induction
enzyme inhibition
substrate competition for the same enzyme
changes in hepatic blood flow

19
Q

What are examples of drugs that cause enzyme induction?

A

phenytoin

smoking

20
Q

What are examples of drugs that cause enzyme inhibition?

A

cimetidine

monoamine oxidase inhibitors

21
Q

Renal metabolism and clearance may be affected by:

A

Changes in GFR
Changes in tubular reabsorption
changes in active drug secretion
nephrotoxicity

22
Q

What drugs may affect glomerular filtration?

A

methylxanthines like caffeine and theobromine which lead to more rapid urinary drug excretion.

23
Q

What drugs may affect active tubular secretion?

A

Probenecid blocks the active tubular secretion of penicillin and some cephalosporin antibiotics.

24
Q

What drugs may affect tubular reabsorption and urine pH?

A

Antacids, sodium bicarbonate
reabsorption of amphetamine
decreases reabsorption of salicylates

25
Q

What are examples of similar PD actions?

A

Narcotics and antihistamines (increase drowsiness)

Promethazine and antihistamines (increase anticholinergic affects like dry mouth blurred vision, and urine retention)

26
Q

What are examples of antagonized PD effects?

A

Beta blockers and vasopressors (cancel each other)

27
Q

What are the time frames for enzymes to develop?

A

2E1 and 2D6 - 1st day
gluconridases - 1st few days
3A4 and 2C - 1st week
2A1 - one to three months

28
Q

How does age affect drug response?

A

renal clearance declines
hepatic blood flow and metabolism also decrease
half life often affected because of larger apparent volumes of distribution of lipid-sol drugs and/or reduction in renal or metabolic clearance.
Greater sensitivity for side effects
Still has increased sensitivity to side effects.

29
Q

What is an example of a beneficial drug drug interaction?

A

Probenecid with penicillin.
Probenecid slows elimination of PCN
carbidopa with levodopa
carbidopa inhibits peripheral metabolism of levodopa

30
Q

Potency of herbal products may be influenced by:

A

Stage of growth when the herb was harvested.
Drying time
Solvents used in the extraction process.
Shelf life and storage conditions of the herbal extract.

31
Q

What are some examples of drug-herbal interactions?

A

Warfarin - Vitamin K
Co-enzyme Q10(similar to Vit K) - Warfarin
Ginger, Garlic, and feverfew - Warfarin may increase bleeding risk
Wheat grass has high levels of Vit K

32
Q

How can foods affect drugs?

A

By changing the pH of the stomach
Complexion ( quinolone antibiotics with calcium)
Competition
Pharmocodynamically antagonize (spinach and broccoli with warfarin)
MAOIs inhibit tyramine metabolism (red wine or cheese) and may cause a hypertensive crisis.

33
Q

What are common examples of chemical-drug interactions?

A

Smoking induces CYP1A2 which may decrease theophylline, diazepam, and tricyclic antidepressants
Ethanol can induce CYP1A2 or CYP2E1, and CYP3A

34
Q

Why is phenytoin given with dietary fats?

A

To get increased bioavailability by enhanced absorption.

35
Q

Why is Probenecid given with penicillin?

A

to inhibit renal tubular secretion of penicillin

36
Q

Why is trimethoprim and sulfamethoxazole given together?

A

for increased efficacy in urinary tract.

37
Q

Why is amoxicillin and clavulanate given together?

A

the beta lactamase inhibitor(clavulanate) inhibits breakdown of amoxicillin

38
Q

Why is HCTZ and triamterene given together?

A

Combine diuretics with different mechanisms of action to minimize potassium loss

Pharmacology Test 4 (5 decks)

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