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Pharmacology > Pharmacokinetics/ Pharmacodynamics > Flashcards

Pharmacokinetics/ Pharmacodynamics Flashcards

1
Q

What is pharmacokinetics

A

The study of what happens to the drug in the animal’s body after it is administered

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2
Q

What is absorption?

A

The process by which a drug crosses various barriers to reach the bloodstream

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3
Q

The only route where absorption is not a factor to be considered is what route?

A

IV

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4
Q

What is bioavailability?

A

The degree to which a drug is absorbed and becomes available via general circulation

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5
Q

What are the two main methods of crossing the cellular membrane?

A

Active & passive processes

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6
Q

What is passive process?

A

No energy expended by the cell - Most drugs cross membranes this way

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7
Q

Give 2 examples of passive processes

A
  1. Simple diffusion - from an area of high concentration to low concentration
  2. Facilitated diffusion - water-soluble drugs cross membranes through pores or channels
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8
Q

What is active process?

A

Requires energy to move substance against a concentration gradient - low to high

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9
Q

What are 2 examples of active processes?

A
  1. Active transport - if close in structure to endogenous substrate
  2. Pinocytosis, phagocytosis
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10
Q

What are 4 factors that affect the absorption of oral drugs?

A
  1. Gut fill & rate of pyloric emptying - delay
  2. Binding to gut contents
  3. Low gastric pH - destroy / inactivate
  4. Presence of GI disease - loss of intestinal villi/ increased rate of emptying
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11
Q

What problems do ruminants present when it comes to oral absorption?

A

Large capacity of rumen dilutes drugs
pH levels cause ion trapping of basic drugs
Microbial activity affects stability of drugs
Rate of passage/ digestibility of feed

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12
Q

Multiple IM/ SQ injection sites increase absorption

A

True

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13
Q

SQ injections are absorbed faster than IM

A

False - IM are absorbed faster due to increased blood flow to muscles

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14
Q

What are 4 things to consider when it comes to the formulation of parenteral drugs?

A
  1. Pyrogen free
  2. Sterile
  3. Adjusted to body pH
  4. Adjusted to body osmolality
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15
Q

Drugs are generally absorbed _______________ through the skin

A

Slowly

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16
Q

Topical medications are usually formulated in ____________

A

Fats - or fat solvents

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17
Q

Increased ____________ allows for increased absorption of topical drugs

A

Circulation

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18
Q

This type of drug absorbed rapidly due to large surface area with excellent blood supply

A

Inhaled drugs

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19
Q

________ soluble drugs have enhanced absorption

A

Lipid

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20
Q

What are some water-soluble antibiotics?

A

Penicillin, aminoglycosides, sulfonamides, B-lactams

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21
Q

What are some intermediate fat-soluble antibiotics?

A

Tetracyclines

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22
Q

What are some fat-soluble antibiotics?

A

Macrolides, fluroquinolones

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23
Q

The ____________ the drug molecule, the easier it can be absorbed

A

Smaller

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24
Q

Non-ionized drugs diffused through cell membranes easier

A

True

25
Q

What types of drugs are absorbed better in acidic and basic environments?

A

Acid drugs - acidic environment
Basic drugs - basic environment

26
Q

The stomach has an ____________ pH, whereas the small intestines have a ______________ pH

A

Acidic, basic

27
Q

Many drugs have ___________ _____________ that control the rate at which they dissolve prior to being available for absorption

A

Protective coatings

28
Q

Skeletal muscle, liver and kidney are well perfused therefore receive significant concentrations of drugs

A

True

29
Q

A drug moves from the absorption site into the ____________ then into the ______________ and finally into the cells

A

Plasma, extracellular fluid

30
Q

What factors affect the distribution rate of drugs?

A

Concentration gradient
Protein binding
Storage in various tissues
Dilution in luminal fluids
Specialized barriers
Disease processes

31
Q

Drugs tent to move from an area of _____________ concentration to an area of _____________ concentration

A

High, low

32
Q

Some drugs may temporarily bind to these and become unable to leave the plasma while bound

A

Plasma proteins (albumin, globulin, glycoproteins)

33
Q

Plasma proteins can be lower in disease states or in young animals, this is called what?

A

Hypoproteinemia - lower plasma proteins means decreased plasma binding and more drug entering ECF; therefore a decrease in dose is required

34
Q

Drugs can be stored in what tissues/ organs?

A

Fat, liver, kidney, bone

35
Q

What is the blood-brain barrier?

A

Exists between plasma and extracellular fluid and has tight junctions - When inflamed it may become more permeable allowing some antibiotics to enter

36
Q

What type of drugs diffuse across the placenta easily?

A

Lipid-soluble

37
Q

Tight capillary and endothelium junctions limit absorption and distribution of drugs in these areas

A

BBB, eye, joint synovia

38
Q

Purulent and necrotic debris may bind and inactivate some antibiotics

A

True

39
Q

Antibiotics enter exudates, abscesses or necrotic tissue very well

A

False - They do not enter very well due to the fibrous capsules the body makes around the infected area and the poor blood perfusion that results

40
Q

Drug metabolism is also known as what?

A

Biotransformation

41
Q

What is metabolism/ biotransformation?

A

The body’s ability to change a drug chemically from the form in which it was administered into a form that can be eliminated from the body

42
Q

All drugs require metabolism before achieving active form

A

False - primidone converted to phenobarbital

43
Q

Metabolism mainly occurs where?

A

Liver

44
Q

The amount of enzymes available that help with metabolism depend on what?

A

Species, age, sex, stress, nutritional status, disease, enzyme induction

45
Q

The first pass effect is only important to remember when administering what kind of drugs?

A

Oral

46
Q

What is the first pass effect?

A

Orally administered drugs are absorbed in the gut before entering the portal circulation - the blood in portal veins is then filtered by the liver before entering systemic circulation - therefore drugs are exposed to metabolic enzymes before entering systemic circulation (are metabolized before having any effect rendering them ineffective)

47
Q

What is the major route for drug excretion?

A

Renal - kidneys

48
Q

In order for a drug to be eliminated by the kidneys it must be ____________ soluble

A

Water

49
Q

Where does biliary excretion happen?

A

Liver - excretes drugs into bile, bile secreted into GIT, eliminated in feces

50
Q

Drugs that are ____________ soluble are generally eliminated through biliary excretion

A

Highly lipid

51
Q

How does intestinal excretion work?

A

Drug is secreted across GIT mucosa by active transport or excreted in gut secretions (ruminant saliva) - are then eliminated in feces

52
Q

Glandular secretions can happen where?

A

Salivary, mammary, sweat glands, male genitalia

53
Q

What is something to be aware of when a drug is secreted through glands?

A

Residues - Some drugs are secreted unchanged which can effect milk when nursing offspring

54
Q

Gas anesthetics are eliminated through the lungs by ____________ _____________

A

Expired air

55
Q

What is the half-life of a drug?

A

The time required for the amount of a drug in the blood to be reduced by one half

56
Q

What does the half-life of a drug dictate?

A

How frequently the drug must be given

57
Q

Shock results in _____________ distribution due to _____________ blood flow to tissues.

A

Decreased, decreased

58
Q

How many half lives are required to remove 99.9% of a drug from the plasma?

A

10

Pharmacology (8 decks)

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