Pharmacokinetics Flashcards

1
Q

What are the 4 fundamentals of pharmacokinetics?

A

Absorption
Distribution
Metabolism
Excretion

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2
Q

What is absorption?

A

Movement of a drug into the blood stream

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3
Q

What are the routes of absorption? (9)

A

Oral
Buccal
Inhalation
Transdermal
Topical
Rectal
IM
IV
SC

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4
Q

How are oral drugs absorbed?
(2)

A

Using 1st pass metabolism
By the liver

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5
Q

How is buccal absorbed? (2)

A

Avoids 1st pass metabolism
High blood flow

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6
Q

How is rectal absorbed?

A

Reduced 1st pass metabolism

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7
Q

How is inhalation absorbed? (2)

A

Large surface area
High blood flow

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8
Q

How are topical drugs absorbed? (2)

A

Has lower therapeutic effect
Has decreased systemic efficacy

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9
Q

How are transdermal drugs absorbed? (2)

A

Smaller molecules, which rely on lipid permeation
Reduced systemic effects

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10
Q

How are IV drugs absorbed? (4)

A

Rapid effect
100% bioavailability
Avoids 1st pass metabolism
Bypasses absorption barriers

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11
Q

How is IM absorbed? (2)

A

Blood flow dependant
avoids 1st pass metabolism

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12
Q

How are SC drugs absorbed? (2)

A

Slow absorption
Blood flow dependant

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13
Q

What are the 6 formulations of drugs?

A

Soluable
Dispersible
Suspensions
Film coated
Slow release
Capsule

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14
Q

Factors which affect oral absorption? (8)

A

Ph
Gut activity
Strength of dose
Solubility of drug
Permeation
Blood flow to GI tract
Gastric emptying time
Physiochemical factors

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15
Q

What are the 4 mechanisms of drug permeation?

A

Aqueous diffusion
Lipid diffusion - (most common)
Facilitated diffusion
Pinocytosis

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16
Q

How does diffusion work? (4)

A

Works best on short distances
Small molecules
Big concentration
Gradient

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17
Q

What factors affect distribution? (5)

A

Lipid solubility
Protein binding - (most important)
Blood flow
Molecular size
Ph

18
Q

Whats the most important molecule for binding?

A

Albumin

19
Q

Which molecules can bind?

A

Only free molecules

20
Q

Which molecules work better for slow release?

A

Larger lipid molecules

21
Q

Which molecules work best for quick release?

A

Hydrogen based smaller molecules

22
Q

What is volume distribution?

A

Ability to cross cell membrane
Lipid drugs (lg) 1-10l/kg
Water soluble (sm) 0.1-1 l/kg

23
Q

Which drugs are easier to distribute?

A

Lipid soluble

24
Q

How are drugs metabolised? (5)

A

Most metabolism happens in the liver
Converts drugs into a more water soluble product
Therapeutic effect decreases after being metabolised
Main enzyme is cytochrome p450
Often divided into 2 phases - oxidation and conjugation

25
Q

What are metabolites?

A

They are toxic but the side effects are the ones used

26
Q

What happens in an overdose situation?

A

There are not enough glutathione to detoxify the metabolites

27
Q

What long term conditions can reduce the livers ability to metabolise drugs?

A

HF and shock

28
Q

What is an inhibitor in relation to metabolism?

A

prolongs the action of a drug

29
Q

what is an inducer in relation to metabolism?

A

Shortens the action of a drug

30
Q

What does a blocker do in relation to metabolism?

A

Acts on non-microsomal enzymes

31
Q

What is the main way drugs are excreted? (2)

A

Glomuler filtration and tubular excretion
Relies on hydrostatic pressure

32
Q

What is meant by tubular excretion?

A

The kidneys are more specific in what it excretes.

33
Q

What happens to drugs excreted by the bile duct?

A

They can remain active in the gall bladder which can cause enterohepatic re-uptake

34
Q

Name all the ways drugs can be excreted. (6)

A

GI tract
Kidneys
Lungs
Sweat
Saliva
Breastmilk

35
Q

What is meant by clearance?

A

clearance is the sum of all elimination routes ie, the amount of drug leaving the body at any given time

36
Q

What are the orders of elimination? (2)

A

zero order - 5% of drugs, cant be sped up
First order - 95% of drugs, rate is proportionate to excretion

37
Q

Which order of elimination is the main one used?

A
38
Q

What processes are used during clearance?

A

Metabolism and excretion

39
Q

What makes drugs easier to excrete?

A

Metabolising them from lipid to water soluble

40
Q

What drug is excreted by the kidneys without being metabolised first?

A

Aminoglycoside antibiotics