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Pharmacology > Carlson Learning Objectives Exam 1 > Flashcards

Carlson Learning Objectives Exam 1 Flashcards

1
Q

What is the purpose of drug metabolism?

A

To eliminate the drug from the body. Does this by polarizing the active lipoidal drug.

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2
Q

What would happen if drug metabolism did not occur?

A

Uncontrolled, prolonged activity of the given drug

Other drugs may never be activated

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3
Q

Where does drug metabolism occur?

A

Hepatic microsomes located in the Smooth ER

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4
Q

Explain what causes renal elimination vs renal absorption

A

Renal elimination can only occur when the drug has been polarized and made water soluble.
If not, the drug will be re-absorbed.

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5
Q

How can renal absorption be avoided by some polar drugs?

A

Penicillin fits into the same transporter for uric acid; this means that Pe can be actively transported out of the renal system

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6
Q

Name the predominating biochemical reaction for phase II drug metabolism. Phase I?

A

Glucouronidation

Hydroxylation

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7
Q

Name the 4 outcomes of biotransformation

A

Active drug > inactive metabolite
Active dug >active metabolite >inactive metabolite
Prodrug >active matabolite>inactive metabolite
Active drug>toxic metabolite

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8
Q

What are two examples of drugs that can become toxic metabolites?

A

Isonizad

Acetaminophen in cats

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9
Q

Dscribe the first pass effect and what steps can be taken to avoid it

A

This is when a drug becomes metabolized before reaching the systemic circulation. Orally administered and IP administered drugs can have this fate. Give more orally or give via an alternate route.

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10
Q

What is the evolutionary basis for drug metabolism?

A

Animals just needed a generic way to eliminate non-nutritive compounds absorbed from the diet.

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11
Q

What animals are the best at metabolizing drugs? The worst?

A

Herbivores are the best. Been exposed to more xenobiotics.

Cats are the worst, poor glucouronidation.

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12
Q

What are some factors that affect biotransformation?

A

Plasma protein binding, hepatopathy, adipose sequestration, age and gender, hypothermia, lactation, etc.

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13
Q

What could decrease decrease an animals drug metabolism? What are ways to overcome that?

A

Animal could be on medication that inhibits microsomal enzymes or have a porto-systemic shunt
Give less of the drug or try a transdermal patch

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14
Q

What could increase an animals drug metabolism and what are ways to overcome that?

A

Taking medication that activates microsomal enzymes or the animal just genetically has an abundance of them.
You could give more of the drug or give via an alternate route.

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15
Q

What is the definition of pharmacogenomics?

A

Relationship between genetic elements and responses to drugs with emphasis placed on differences.

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16
Q

What are the three main mechanisms for pharmacogenetic differences?

A

Alterations in drug metabolism
Alterations in the target of the drug
Altered drug transport issues

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17
Q

Name three types of undesirable effects of altered drug metabolism:

A

Prolonged effect: Viagra (priapism)

Toxic effect: Acetaminophen in cats and isoniazid

Side effect: Opioids can act as stimulats in cats and horses as they inhibit the removal of dopamine from synapses.

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18
Q

Describe the mechanism and potential evolutionary basis for acetaminophen toxicity in cats

A

Cats are very poor at glucouronidation, because they lack the genes necessary.
Acetaminophen is also a phytoalexin, which is a plant derivative. Carnivores have no use for this

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19
Q

Name two types of alterations in drug metabolism that can lead to treatment failures:

A

Atropine in bovine: plasma esterases plus hepatic activity rapidly inactivate this
Lack enzyme needed for drug activation. Cats cannot convert primidone to phenobarbital

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20
Q

Describe two outcomes related to alterations of a drug target:

A

No activity of the drug: Fluoroquinolone antibiotics are inactive vs bacteria with an altered enzyme

Drug side effect: erythromycin can sporadically cause GI distress. Esp. motilinR subtype A

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21
Q

Describe the double edged sword of drug transportation:

A

Selective tissue distribution is good.

Toxic accumulation is bad.

22
Q

What are the 5 overall outcomes of pharmacogenomic differences?

A 
Toxicity
Prolonged effect
Unwanted side effect
Drug failure 
Exploitable feature: some drugs that accumulate in CNS can be used to treat meningitis
23
Q

Describe the pharmacologic basis for ivermectin toxicity in collies

A

Deletion mutation of mdr1 gene. Dogs that are homozygous for this mutation are affected. With this mutation the transporter does not work and ivermectin accumulates in the brain.

24
Q

How do auto-active receptors present a pharmacologic problem?

A

Receptor mutation where the receptor is insensitive to the antagonist or inhibitor.
The reaction is always going, so the drug or inhibitor have no effect.

25
Q

NEXT STUFF IS DAY’S STUFF

A

YEEYEE

26
Q

Define concentration-dependence

A

The % of receptors bound by a drug increases as the concentration of that drug increases

27
Q

Define saturability

A

This is once all the receptors are bound by a drug, increasing conc of drug will have no effect

28
Q

What is the dissociation constant?

A

KD = (DxR)/DR; it is the relationship between drug, receptor, and drug-receptor complex

29
Q

Why is the dissociation contstant important?

A

It describes the drug concentration that is required to produce half the max occupancy of the receptor population

30
Q

Define affinity:

A

This is chemical attraction

31
Q

What is the equation for affinity?

A

1/Kd

32
Q

What does a high affinity mean?

A

This means the drug has a high affinity for the receptor, which means the DR will be high and will be a low dissociation constant

33
Q

What is specificity?

A

This refers to the selectivity of the drug for a particular receptor

34
Q

What are the three types of modulation of drug binding to receptors and what affect do they have?

A
  1. Competitive inhibition of binding; Will increase the Kd
  2. Non-competitive inhibition of binding; number of receptors available to be bound are reduced, but the Kd is unaffected
  3. Allosteric modulation of binding; affinity for the first drug is changed
35
Q

What is an agonist?

A

Produces the maximum response that can be elicited by those receptors

36
Q

What is a partial agonist?

A

Produces a response, but is less than max that can be elicited by other agonists at the same receptors

37
Q

What is an antagonist?

A

Binds to the receptor but does not activate the system. Competitively BLOCKS the activation.

38
Q

Define EC50:

A

The concentration required of a drug to produce 50% of that drug’s max response

39
Q

What is the main measure of a drug’s potency? Is a high or low number more potent?

A

EC50; a low number indicates higher potency

40
Q

What is the difference between Kd and EC50?

A

Kd: measures affinity
EC50: measures potency

41
Q

What is the dose-response relationship?

A

% of patients that reach a clinically defined response at or below that dose

42
Q

Define ED50:

A

Dose required to elicit a response in 50% of population

43
Q

Define therapeutic index. Is it better to be high or low?

A

LD50/ED50; Want a high therapeutic index

44
Q

What is the standard safety margain?

A

This is the % by which the dose effective in 99% of the population must be increased to cause death in 1% of the population. ((LD1/ED99)-1)x100

45
Q

What are the four ways a drug can cross a membrane?

A

Passive diffusion, facilitated diffusion, active transport, and pinocytosis

46
Q

What are the three ways a drug can passively diffuse across a membrane?

A
  1. Non-polar molecules diffuse across the lipid bilayer
  2. Oil-water partition coefficient
  3. pH and polarity
47
Q

What does Ka stand for?

A

This is the association constant. It describes the constant relationship between the concentrations of H+, A, and HA

48
Q

What is the definition of pKa?

A

This is the pH at which 50% of the molecule is protonated

49
Q

What environment would be favorable for diffusion with a weak acid drug?

A

A low pH environment; has a lot of H that can cause HA formation.

50
Q

What determines the extent of ionization?

A

The difference between pH and pKa

Pharmacology (9 decks)

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