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Pharmacology > Principle of Pharmacology - pharmacokinetics > Flashcards

Principle of Pharmacology - pharmacokinetics Flashcards

1
Q

Pharmacokinetics

A

How the body affects the drug

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2
Q

Pharmacodynamics

A

How the drug affects the body

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3
Q

Excipients

A

Everything except the drug itself (colouring, flavourings, sweeteners)

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4
Q

First Pass Effect

A

Rapid uptake and metabolism of compound in LIVER before it reaches systemic circulation

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5
Q

Idea of first pass effect

A

So the idea of the first pass effect is that when you take a compound it goes to your liver to be metabolized. This means that the drug concentration will drop therefore once it is done in the liver it can reach its target area but with a lower dose. Lower dose of absorption = decrease in effect

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6
Q

What happens when you have a patient come in with liver damage?

A

When the drugs reach the damaged liver it will not be broken down as efficiently if it were a person with a normal liver. This means that the drug percentage released to the rest of the body will be greater than someone with a liver that works properly. This can lead to serious consequences –> overdose…

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7
Q

Drugs are given as a

A

Formulation

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8
Q

Examples of formulations

A

tablets
capsules (powder in gelatin coating - fast absorption)
caplets (easily swallowed)
liquids (fastest absorption)

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9
Q

What makes a drug cheap?

A

When it doesn’t have to be sterile - PO or SL formulations

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10
Q

Bioavailability and use insulin as an example

A

Fraction of drug available in systemic circulation
PO: lower than if you were given IV
Insulin: if given PO enzymes in stomach would break it down before getting into circulation. Injected is the best way to go!

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11
Q

What does SL, SC, IM, and IV administration all have in common?

A

High bioavailability
By passes stomach and intestine
NO first pass (doesn’t go to liver)

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12
Q

Name the three enteral methods for drugs to be administered

A
  • PO (orally)
  • PR (rectal)
  • SL (sublingual)
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13
Q

Name the five parenteral methods for drugs to be administered

A
  • IV
  • IM
  • SC
  • Transdermal
  • Inhalation
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14
Q

Why would we use the enteral route for a drug?

A
  • Convenient

- Negative: first pass effect

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15
Q

Why would we use the parenteral route for a drug?

A
  • No first pass effect
  • Quick to get into circulation
  • More drug reaches circulation
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16
Q

Why would we use the topical route for a drug?

A

Local/sustained effect

17
Q

Most drugs use (active OR passive) movement across the membrane

A

Passive!

Why? Because it goes down the concentration gradient when moving across the membrane.

18
Q

3 chemical factors that affect the way a drug is absorbed

A
  1. Size
  2. Lipid solubility - lipid soluble drugs will absorb more quickly because they pass readily through membranes (water soluble drugs will pass more slowly) * phospholipid bi-layer of cells acts as a barrier to large water-loving molecules
  3. Drug charge - development of an electric charge decreases drugs ability to move around body
19
Q

4 physical factors that affect the way a drug is absorbed

A
  1. Blood flow to the site of absorption
  2. Surface area for absorption - high surface area in intestine
  3. Contact time - if you have diarrhea then the drug will have decreased contact time compared to if you did not have it
  4. Drug formulation - size, gel coatings…
20
Q

Which administration would we NOT use if a person is in shock?

A

Subcutaneous because blood flow to the extremities is greatly reduced

21
Q

The distribution of a drug depends on…

A

rate of blood flow

22
Q

Why will the tissues with high blood flow receive more drug than tissues that have low blood flow to them? Examples of rapid distribution and slow distribution.

A

Tissues with high blood flow will receive more drug because it will get to its destination faster and more frequently than a place with low blood flow

  1. heart, liver, kidney, brain
  2. muscle, fat, skin (all dense)
23
Q

Drug distribution is determined by three factors

A
  1. Rate of blood flow to tissues
  2. Exiting vascular system
  3. entering cells to target goal
24
Q

When a drug exits the vascular system what are the factors that affect it?

A
  1. lean mass (watery environment will allow drug to be absorbed more quickly)
  2. Fat solubility
  3. Plasma Protein Binding*
25
Q

Plasma Protein Binding*

A

Drugs will bind to plasma proteins –> when they are NOT bound they have effects on the body but when they are bound they don’t have any affects

26
Q

What happens when a person does not have sufficient plasma protein binding sites Eg: person with low albumin

A

This person will have a greater drug effect in the body than someone with lots of PPB sites

27
Q

What are the two ways the body gets ride of drugs?

A

Metabolism and excretion

28
Q

Where is drug metabolism mainly occurring?

A

Liver - it alters the drug using cell enzymes

29
Q

What family of enzymes metabolize drugs?

A

Cytochrome P450 Superfamily

30
Q

What is the most common therapeutic consequence of drug metabolism?

A

Accelerated renal drug excretion

31
Q

What does accelerated renal drug excretion aid in?

A

Aids water solubility

32
Q

What can grapefruit juice act as?

A

It can act as a CYP inhibitor

33
Q

What happens if CYP is inhibited?

A

Then there will be no breakdown of drugs. When there is no breakdown of drugs, then body will continue to take up the drug -> constant effect

34
Q

What are the two ways a drug can be excreted?

A
  1. Filtration using glomerulus

2. Active transport using specialized carriers

35
Q

What two things determine the duration of drug effects?

A

Metabolism and excretion

36
Q

Therapeutic Range

A

Range of drug level between minimum effective concentration and toxic concentration

37
Q

Drug-half life

A

Time required for drug to decrease by 50%

38
Q

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

A

4-5 half lives

39
Q

Does shorter half life mean you should take more OR less of a drug to have greater effects?

A

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Pharmacology (8 decks)

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