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Pharmacology > Drug overview- Exam 1 > Flashcards

Drug overview- Exam 1 Flashcards

1
Q

Approximately how many applications are there for novel drugs every year?

A

30-40/year

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2
Q

What are the implications of that for education- for the class?

A

Constant change- we will constantly be adding new “tools” to the toolbox
- Think correctly and accurately about drugs especially when presnted with new products

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3
Q

What is the primary source of information regarding the efficacy and safety of new drugs?

A

The drug company

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4
Q

What are the implications of where to get information on drug efficacy and safety of new drugs?

A
  • we need to be knowledgable about how the drug works.

- Need to be able tos peak about the topic as well

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5
Q

What is the Dissociation Constant (KD)

A

It is the drug concentration required to produce half maximal occupancy of receptor population.

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6
Q

How do you measure affinity?

A

chemical attraction

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7
Q

A drug with a high affinity for receptor (how does it affect Kd)

A

has a low Kd

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8
Q

A drug with a low affinity for receptor (how does it affect Kd)

A

Has a high Kd.

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9
Q

Specificity definition

A

Refers to the selectivity of the drug for a particular receptor
- a drug that binds to only 1 particular receptor, it has complete specificity

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10
Q

How to evaluate the specificity of drugs?

A

It is the difference betweenthe 2 dissociation curves of certain targets.

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11
Q

What is the competitive inhibition of binding?

A

Competative inhibition will appear to increase the KD- produce an apparent reduction of the affinity of both drugs for those receptors.

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12
Q

What is the B max of a dissociation curve?

A

This referred to the maximum percentage of receptors that a given drug can occupy.

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13
Q

What is non-competative binding

A

When a drug binds irreversibly to a receptor,other drugs which normally bind tothat receptor cannot displace it. Thus, in the presence of a drug which binds irreversibly to a population of receptors, the number of receptors available to be bound by a reversible-binding is effectively reduced.

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14
Q

What is allosteric modulation of binding

A

Binding fo a drug to a recpetor may be increased or decreased by a second drug that does not actually bind to the same site on the receptor.

  • The 2nd drug binds to a secondary or modulatory site on the receptor.
  • the total number of receptors is not changed but the affinity of the receptor for the first drug is changed. it can either be increased or decreased.
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15
Q

What is drug efficacy

A

This is the percentage of the Maximum response that can be mediated by a receptor-effector system
- Maximum response -> complete efficacy
1/2 maximum response -> 50% efficacy

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16
Q

What is a full agonist

A

Produces the maximum response that can be elicited by those receptors
- this causes a full effect

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17
Q

Partial agonist

A

Produces a response, but it is smaller than the maximum response that can be elicited by other agonist at the same receptor.
- This has less efficacy

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18
Q

Antagonist

A

Binds to the receptor, but does not activate the effector system.

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19
Q

Potency (what is this)

A

A relative measure of drug activity, the concentration or dose of a drug required to produce an effect compared to the concentratio nrequired for other agents to produce the same effect.

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20
Q

Explain what EC50

A

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

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21
Q

If you have a low EC 50, what would happen to your potency?

A

Potency would be increased

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22
Q

If you have a high EC 50, what would happen to your potency

A

Potency would decrease

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23
Q

What is ED 50 ->

A

This is the effective dose to elicit a theraputic response in 50% of the population

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24
Q

What is LD 50

A

This is the lethal dose in 50% of the population

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25
Q

What is the primary source of movement across membranes

A

passive diffusion

26
Q

What happens if you have a weak acid and are moving from a low pH to a High pH?

A

The protonated form will diffuse across the membrane. (This would be uncharged)

27
Q

What happens ifyou put a weak acid in a high pH environment.

A

The acid will be unprotonated.

28
Q

What happens if your pH is higher than the pKa

A

90% of it will be dissociated.

29
Q

What type of a drug is good as an orally administered drug

A

A weak acid that is in an environment lower than its pKa, it can freely diffuse across the membrane, & absorbed well.

30
Q

Pharmacokinetics definition

A

Movement of a drug

  • Absorbed
  • Distributed
  • Metabolized
  • Excreted
31
Q

Bioavailability of drugs- Define

A

Quantifies the fraction of a drug that is absorbed and available to produce its systemic effect.

  • Extent of absorption (amount-
  • Rate of absorptino (amount per unit of time)

you want a new drug to be 60% bioavailable to ensure there is no difference between individuals

32
Q

Where in the liver is the sight of the most drug metabolism

A

the smooth endoplasmic reticulum

33
Q

3 reasons drug metabolism is important

A

1) the absence of drug metabolism would lead to prolonged uncontrolled activity of a given drug
2) Some drugs require modification for activity ie. codeine -> morphine
3) Evolutionary basis: you need to eliminate non-nutritive compounds absorbed from diet

34
Q

What is the kideny’s goal in drug metabolism to eliminate drugs

A

Polarize the active lipoidal drug so it can be eliminated through the kidney

35
Q

What form does the drug need to be in to ensure renal elimination

A

Needs to be soluble/polar

- if not the drug is reabsorbed

36
Q

What are the 2 phases of hepatic metabolism of drugs

A

Phase I- initial polarization (addition of hydroxyl group- water soluble)
Phase 2- conjugation- Glucuronidation (very polar and water soluble)

37
Q

What species have poor glucuronidation

A

cats and polar bears

38
Q

What are the 4 possible outcome sof biotransformation of drugs

A

1) active drug to inactive metabolite
2) active drug to active metabolite to inactive metabolite
3) Inactive drug (prodrug) to active metabolite to inactive metabolite
4) active drug to toxic metabolite

39
Q

What is the first pass affect

A

This is associated with oral administration of drugs as well as intraperitoneal administration- the drug enters portal circulation and will go to th eliver for metabolism before reaching systemic circulation

40
Q

What type of orally administered drug is not affected by the First Pass Effect

A

“Polar-enteric” antibiotics- these drugs stay in the gut after oral administration

41
Q

What are extrahepatic routes of drug metabolism

A

kidneys
nervous system
small intestine (first pass effect)

42
Q

How do polarized drugs exit the hepatocyte after being metabolized in the SER

A

active transport

43
Q

Pharmacogenomics definition

A

The relationship between genetic elements and responses to drugs with emphasis placed on differences therein

44
Q

What is the basisfor pharmacogenomics?

A

the basis for:

  • some drug toxicities
  • some drug side effects
  • some drug failures.
45
Q

What are the 3 mechanisms of pharmacogenomic differences

A

1) alterations in drug metabolism
2) alterations in the target of the drug
3) Altered drug transport issues

46
Q

WHat are undesirable affects of drug metabolism?

A

1) prolonged unwanted activity
2) toxic metabolite formed following drug metabolism
3) unwanted, unrelated, unexpected side effect: non-toxic

47
Q

Isoniazid toxicity

A

causing hepatitis- this forms a strong electrophyle, which causes hepatitis, and hepatocellular death

48
Q

Acetominophen toxicity

A

normally metabolized by glucuronidation. Cats have poor capacity for glucuronidation. All other metabolic conversions lead to electrophiles resulting in hepatocellular injury and hepatitis

49
Q

What is a treatment for a cat and acetaminophen toxicity

A

acetylcysteine- has a high affinity for electrophilic acetaminophen derivatives. Also used as a mucolytic drug.
Must be given within 24 hours of the toxicity ingestion

50
Q

Opioid analgesics in horses: what is the response

A

results in unexpected effects- Opioid metabolites inhibit the removal of dopamine from the synapse in these animals. Opioid metabolites act as CNS stimulants by maintaining dopamine within the synapse

51
Q

What is the cause of deminished activity or complete drug inactivity

A
  • presence of an extrahepatic enzyme that rapidly inactivates the drug (ie atropine in bovine as plasma esterases inactivate it)
  • Lack of an enzyme needed for activation of an inactive drug (prodrug) cats are unable to convert primidone to phenobarbital
52
Q

What are situations of altered target of a drug

A
  • Drug itself is inactive, receptor mutations, inactive receptors
  • Drug side effects
53
Q

Erythromycin

A

antibiotic used versus respiratory infections

- gastrointestinal distress is sporadically reported

54
Q

How do you measure the average drug exposure in a patient?

A

Evaluate the blood plasma

55
Q

What is the difference between absorption and bioavailability?

A

You have the first pass affect. You have metabolism that occurs in the gut and liver. This decreases the bioavailability of the drug.

56
Q

A drug that is low unbound- high bound fraction goes to what organ?

A

The liver- this is more lipophilic

This is impacted by liver function

57
Q

A drug is high unbound- low bound fraction and goes to what organ?

A

This goes to the kidney

This is impacted by renal function

58
Q

How do you calculate the clearance of a drug?

A

It is the Dose/AUC AUC is the area under the curve or the net exposure

59
Q

Explain the Cl=QxE equation

A

it is to calculate the clerance of a drug. This is a factor of the cardiac outpoot and the extraction ratio

60
Q

How do you use pharmacokinetics in dose determination?

A

dose=clearance/bioavailability% x concentration in the plasma

Pharmacology (7 decks)

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