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Ther 201 1st Exam > Pharmacokinetics > Flashcards

Pharmacokinetics Flashcards

1
Q

Metabolism Vs Excretion

A

Metab - change in structure

Excretion - removal of unchanged drug

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2
Q

Reason why these are poorly absorbed:
Penicillin G and Insulin?
Tetracyclines?
Aminoglycoside antibiotics?

A

destroyed by stomach acid/digestive enzyme;
chelated to components of food to form insoluble complexes;
Polar compounds cannot cross the wall

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3
Q

Is drug distribution reversible?

A

Yes

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4
Q

Factors affecting drug distribution

A

Cardiac output, Perfusion, Permeability, Protein Binding

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5
Q

Displacement of drug from protein binder will cause adverse effects only when: 2 reasons

A

the drug has a very narrow therapeutic index and when most of the drug is located in the intravascular compartment

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6
Q

PK - Distribution:
@ liver and spleen?
@ brain?

A

liver and spleen are very leaky, drug leaves the capillary regardless of its solubility

brain capillaries have tight jxns, use of transporters to diffuse drugs, lipophilic drugs can diffuse across

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7
Q

What are the 2 amines that has limited brain penetration capacity;
Give their precursors that allow them to cross

A

Dopamine and Serotonine;

Levodopa and 5-hydroxytryptophan;

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8
Q

Molecular function of Microsomal CYP450 Monooxygenase

A

transfer electrons from NADPH to an oxygen molecule and thus oxidize drugs

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9
Q

What is an inducer drug? What are its effects

A

causes the expression of more CYP enzymes

greater drug elimination, more metabolites (can include toxic), inc prodrug activation

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10
Q

A transporter moves one drug from one compartment to another. What is the transporter protein that involved in drug resistance of cancer patients?

A

P-glycoprotein

It is overexpressed in tumor cells; pumps out anticancer drugs

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11
Q

Assumptions in a One-compartment Model

A
  1. the body is one single process
  2. drug is distributed instantaneously and is mixed well
  3. Equilibrium exists between blood and tissue
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12
Q

2 Types of Compartments

A
  1. Central - high blood flow, rate of elimination = rate of entry, brain, liver, spleen, kidney
  2. Peripheral - slow blood flow, rate of entry > rate of elimination, adipose and muscles
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13
Q

Rule of Parsimony

A

Use simplest model possible

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14
Q

Graph of a drug in:

single compartment and IV route

A

Semi-log graph

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15
Q

The only assumption in a Non-Compartmental Model

A

The terminal phase of the graph/curve should act like a 1-compartment model

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16
Q

Factors affecting Absorption

A

SSSGR:

State, Solubility, Surface Area, GET, Route

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17
Q

Protein Binding:
Acidic drugs bind to?
Basic drugs bind to?

A

Albumin

Alpha-glycoprotein

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18
Q

Give the reaction involved in metabolizing these:

Ethanol, Chloramphenicol, Paracetamol, Isoniazid,

A

Oxidation;
Glucoronization;
Sulfation;
Acetylation;

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19
Q

Common Liver Enzyme Inducers

A

P - Phenobarbital (a barbituate), Phenytoin (blocks Na channels, anticonvulsant)
R - Rifampicin (Anti-TB drug)
C - Carbamezapine (same w/ Phenytoin), Chronic alcoholism

20
Q

What is an Inhibitor? What are the effects of inhibitors?

A

Inhibitor inhibits hepatic enzymes;
Active drugs are not inactivated hence prolonged drug effect,
Prodrugs are not activated

21
Q

Examples of Liver enzyme inhibitors

A

MEDVICK-GA:
Metronidazole, Erythromycin, Disulfiram, Valproic acid, Isoniazid, Cimetidine, Ketoconazole, Grapefruit Juice, Acute Alcoholism

22
Q

Which is filtered more or favored?
Ionized vs non-ionized drug?
Bound or free drug

A

Both are filtered.

Only free drug is filtered.

23
Q

Only _____ form is favored to be actively secreted and reabsorbed

A

non-ionized

24
Q

fastest route of absorption?

A

Inhalation; IV route does not involve absorption.

25
Q

When do you see the first pharmacologic effect of a drug?

A

When the drug reaches Minimum effective conc.

26
Q

In a graded response graph, where can you see the duration of action?

A

Found between two points. These points are the Minimum Effective Concentration. the 1st is during absorption and the 2nd is during elimination

27
Q

Two properties that enable a drug to cross Blood Brain Barrier

A

High Lipid solubility

Low Molecular weight

28
Q

True to False

All drugs that can cross the Blood-Brain Barrier can also cross the placenta

A

True

29
Q

Characteristics of a drug safe for pregnant women

A

Large molecular size
Hydrophilic drug
Protein bound drug

30
Q

What is Redistribution?

A

When lipid soluble drugs are redistributed to the fat tissues. Contributes to bigger half life. Multiple doses leads to greater effect.

31
Q

Zero Order Elimination Rate:
Amount eliminated?
Rate of elimination?
Half life? Saturation?

A

Constant AMOUNT eliminated;
Rate of elimination is independent of concentration;
No fixed half-life; There is saturation;

32
Q

Zero Order Elimination Rate:

Examples: Zero PEAs for me

A

Phenytoin
Ethanol
Aspirin

33
Q

Graph of Zero Order:
In units of drug scale?
In log units scale?

A

Linear, negative slope;

Parang ihi

34
Q

1st Order Elimination Rate:
Amount eliminated?
Rate of elimination?
Half-life?

A

Constant FRACTION eliminated;

Half-life is constant

35
Q

Graph of 1st Order:
In units of drug scale?
In log units scale?

A

Exponential decay;

Linear, negative slope

36
Q

The Steady state is dependent on what variable?

A

It is dependent ONLY ON HALF LIFE.

It is independent of dose size and frequency/

37
Q

How many half lives does a CLINICAL steady state entail?

A

4-5 half lives, 95%

38
Q

How many half lives does it take to reach MATHEMATICAL steady state?

A

7+ half lives, 99-100%

39
Q

Rate of infusion does not affect the time it takes to reach steady state, neither does Maintenance Dose. What does it affect?

A

The plasma concentration of a drug at steady state

40
Q

When will the Loading dose be equal to twice the Maintenance dose?

A

When you administer the drug at each half time (assuming normal clearance and same F)

41
Q

Dose Response Curve:

Same and parallel slope?

A

Same receptor; nearer to the left, greater affinity for receptor

42
Q

Dose Response Curve:

Potency?

A

Nearer to the left, greater potency;

Can only compare potency if curves dont cross each other

43
Q

Dose Response Curve:

Efficacy?

A

The more it is shifted along the Y axis, towards the North, the greater its efficacy

44
Q

When can a partial agonist be an antagonist?

A

When it is administered along with the full agonist. It will compete for the same receptor sites. Effect will be intermediate.

45
Q

What is the effect of a partial agonist?

noncompetitive agonist? competitive agonist?

A

decrease efficacy;
decrease efficacy;
decrease potency;

46
Q

Pharmacologic vs Physiologic Antagonistm

A

Pharma: 2 drugs bind to same receptor
Physio: 2 drugs bind to 2 different receptor. The receptors have antagonistic effects.

Ther 201 1st Exam (8 decks)

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