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Principles Of Disease W6 - 10 > Drugs > Flashcards

Drugs Flashcards

1
Q

Pharmacodynamics vs pharmacokinetics?

A

D is what drugs does to body, K its what body does to drug (ADME)

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2
Q

ADME

A

absorption, distribution, metabolism, excretion

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3
Q

Therapeutic index

A
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4
Q

What is absorption?

A

Process of mass transfer from site of administration to blood stream (plasma). Commonly oral or IV

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5
Q

Distribution?

A

How the medication moves around the body

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6
Q

What is bioavailability?

A

Percentage of administered drug that makes it to the biophase

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7
Q

What is first-pass metabolism and when does it commonly occur?

A

Drug is metabolised before reaching bio phase so its bioavailability is less than 100%. Occurs in liver and GI tract has enzymes which can break down drug before reaching biophase

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8
Q

What determines extent and rate of absorption? (5)

A

Lipophillicity, molecule size and shape, solubility, gastric emptying time, pH in gut

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9
Q

What is the half life of a drug?

A

Time taken for drug conc. in plasma to half. Big half life = toxic and low = no therapeutic effect

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10
Q

How does cMax relate to drug concentration?

A

max conc drug reaches in plasma. High cMax = better absorption and higher bioavailability so less doses to avoid toxicity

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10
Q

How does cMax relate to drug concentration?

A

max conc drug reaches in plasma. High cMax = better absorption and higher bioavailability so less doses to avoid toxicity

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11
Q

What is a transcellular fluid?

A

Made by epithelial cells, includes CSF, peritoneal fluid

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12
Q

What is paracellular vs transcellular movement?

A

P = filtration out of capillary bed. T = transport in and out of endothelial

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13
Q

What is tMax

A

time taken to reach cMax. short means rapid onset of action, but goes away quickly so you need more doses

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14
Q

What method of administration would you chose if you want systemic absorption?

A

Oral, Rectal, Sublingual

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15
Q

What method of administration would you chose if you want parenteral absorption?

A

Intramuscular, Subcutaneous

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16
Q

Why is pH important in drug administration?

A

only unionised drug can be absorbed, so if pH is too low drug can be ionised

17
Q

Why is lipophillicity of a drug important?

A

more lipophilic means it will transport through membranes better, but too lipophilic is bad

18
Q

Which parts of the body are more protected? how?

A

Brain, testes, ovary, placenta. Have tight junctions so prevent capillary transport

19
Q

How do free drug and plasma proteins correlate?

A

Plasma proteins bind to drugs and this means they’re inactive. Free drug can be absorbed and distributed.

20
Q

What is vD and how does it correlate to drug duration in plasma?

A

vD is volume of drug available for distribution. Drugs with low vD stay in plasma longer so doesn’t go to other tissues as fast.

21
Q

What is steady state?

A

When drug is constantly at an effective therapeutic concentration

22
Q

Whats special about general anaesthetic?

A

It is highly lipophilic so rapidly distributes to all the tissues arrives at

23
Q

What is perfusion?

A

passage of blood/lymph to tissue/organ

24
Q

zero order kinetics

A

conc. of drug in body constantly decreases in a straight constant independent of concentration of drug

25
Q

first order kinetics

A

rate of reaction is directly proportional to concentration - dependant on concentration of drugs. more time goes on, rate of drug decreases more rapidly

26
Q

What are the three ways that the body protects itself from xenobiotics?

A

BBB,
Removal via urine or bile
Biological transformation via phase I and II

27
Q

What is biotransformation?

A

Increasing polarity of drug so its less likely to be reapsorbed by kidney tubules

28
Q

Phase I? and site?

A

Add functional group via oxidation, or modification of a current functional group on the drug via hydrolysis, in liver and extrahepatically

29
Q

CYP450?

A

membrane proteins that are important phase 1 enzymes. they oxygenate the drug by adding a single oxygen atom, forming a functional hydroxyl group. this forms. handle for phase II to occur

30
Q

What occurs in phase II?

A

Produces larger and more polar molecules by attaching hydrophilic groups. produces inactive form of drug which is usually a weak acid which has a lower chance of being reabsorbed in kidneys.

31
Q

How do phase II metabolites become inactive?

A

They’re more likely to bind to plasma proteins so they become inactive and cant spread to other tissues

32
Q

what is the significance of glucaronic acid

A

its an important co-factor in phase 2 metabolism for most drugs

33
Q

What is warfarin?

A

its a drug which prevents clot formation in diseased people, and this drug is metabolised by a type of CYP450 - CYP2C9

34
Q

What is clearance of drug?

A

Volume of plasma where drug would be completely removed per volume of time. Occurs via hepatic or renal mechanisms

35
Q

How should we change drug dosage based on clearance?

A

If clearance is high, drug dosage should be increased as its cleared from plasma faster.

36
Q

What factor allows a drug to be filtered by the kidney?

A

It must be present in the plasma in a free form (not bound to plasma proteins) and the kidney must be in good health, with well perfusion

37
Q

How do larger molecules enter the kidney for filtration?

A

through transporters (protein channels)

38
Q

What does transport of drug into the kidney depend on?

A

flow rate and free drug conc.

39
Q

What factor effects reabsorption of drug in the kidneys?

A

if drug is too lipophilic, its more likely to be reabsorbed. this is why phase I and II metabolism occur, to make drug larger and more soluble

40
Q

What makes a drug less likely to be reabsorbed?

A

More polar, more alkaline urine (ionises the weak-acid conjugated drug more so cant be reabsorbed)

40
Q

What makes a drug less likely to be reabsorbed?

A

More polar, more alkaline urine (ionises the weak-acid conjugated drug more so cant be reabsorbed)

Principles Of Disease W6 - 10 (17 decks)

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