Lesson A5 - DRUG ABSORPTION, DISTRIBUTION, METABOLISM, AND EXCRETION Flashcards

1
Q

What are 3 ways drugs can be administered?

A
  1. By inhalation
  2. Rectal Administration
  3. Oral Administration
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2
Q

How do drugs in the form of gas enter the bloodstream?

A

Through the lungs

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3
Q

Why was Bronchodilator and anti-inflammatory drugs used to treat asthma and other respiratory diseases administered by inhalation?

A

In order to produce a direct effect on the respiratory effect and to minimize effects of the drug(s) on other organs.

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4
Q

What are a couple reasons for a drug to be administered rectally?

A

When a patient is vomiting or nauseous and cannot be taken by mouth

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5
Q

What type of administration is sometimes used when a patient is vomiting or nauseous?

A

Rectal administration

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6
Q

What is one of the benefits from rectal administration of a drug?

A
  • Local effect

- EXAMPLE –> relief of hemorrhoids

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7
Q

Systemic absorption is not as ___________ from the _________________ as from the __________.

A

Favourable, rectal mucosa, intestine

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8
Q

This is the most convenient route for the administration of drugs and over 90% of the drugs are administered by this route. What route is this?

A

Oral administration

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9
Q

What is the only practical route for self administration of drugs?

A

Oral administration

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10
Q

What are the steps which a tablet must undergo before it is able to exert an effect.

A
  1. The tablet must disintegrate into small particles in the fluids of the stomach and/or intestine.
  2. Next, these small particles must dissolve in the fluids of the stomach and/or intestine.
  3. Once the drug has dissolved, it may be absorbed through the stomach wall into blood vessels and carried in these blood vessels to its site of action.
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11
Q

When is the absorption of a drug into the blood stream favoured? Why?

A

When the stomach is empty because because this allows more ready access of the drug to the stomach wall

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12
Q

What is generally the major site of drug absorption

A

The intestine

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13
Q

In order for a drug to create a therapeutic effect what must happen?

A

Only drugs that are absorbed into the blood

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14
Q

What happens if a drug is not absorbed in the blood stream?

A
  • It will pass through the intestines and leave the body through the kidneys
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15
Q

What portion of the drugs can be absorbed in the blood?

A

Only that portion of the drug that goes into solution in the fluids of the stomach and intestines can be absorbed into the blood

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16
Q

How must a tablet be created?

A

The tablet must be made in such a way that it will disintegrate into small particles and then dissolve in the stomach and intestinal fluids.

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17
Q

What are the 2 things that the government requires in order for a tablet to be properly made?

A
  1. The tablet must be shown to contain adequate amounts of the chemical responsible for the activity of the drug
  2. The tablet must disintegrate in a test-tube test.
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18
Q

Why are the 2 things that the government requires for a tablet to be made properly insufficient to insure that the drug will be effective?

A
  1. The disintegration time measured in a test-tube may not in fact correspond to the disintegration time in body fluids
  2. Tablets are made in different ways by different companies and contain different additives, but they must produce the same blood levels of the active ingredient.
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19
Q

What do we require to know about a tablet in regards to blood level?

A

We require to know is the blood level of the drug at different time intervals after administration.

20
Q

Define Bioavailability

A

Bioavailability is defined as the percentage of a drug contained in a drug product that enters the systemic (general) circulation in an unchanged form after administration of the product. The concept also includes the rate at which this entry occurs.

21
Q

Define the generic name of a drug

A

The name given to a drug by various committees ( Not the scientific name) –> To simplify the scientific chemical term

22
Q

Define brand name of a drug

A

The proprietary name given to the drug by the company who is going to market it

23
Q

Why is the amount of advertising that goes towards new and old drugs a bad thing?

A
  • Someone can get bias thoughts and pick a drug that might be less effective because of a good advertisement.
  • Unbiased review –> read “Medical Letter on Drugs and Therapeutics”
24
Q

What does the Drug benefit formulary/Comparative drug index tell you?

A

Lists only drug products which are believed to be good quality. Drug listed in this formulary are considered therapeutically interchangeable

25
Q

Why are drugs sometime confusing for general practitioners?

A
  • Because so many brand names

- It would be better if drug companies put the generic name followed by the brand name

26
Q

True or False? It had been shown that drug products made by different companies can result in markedly different blood levels

A
  • True
  • It has been way better since 1990 when Health Canada started to check their bioavailability. In 2012 this is not a problem
27
Q

Why are additives added to various drugs?

A

To used together with the drug in order to ensure appropriate disintegration and dissolution of a drug.

28
Q

Define Therapeutic Jungle

A

There are so many drugs and drug combinations on the market

29
Q

What are 3 problems associated with how many drugs are on the market?

A
  1. Confusing because 1 generic name but so many brand names
  2. Overwhelming drugs that are introduced
  3. Large amount of advertising that goes towards marketing new and older drugs
30
Q

Why are so many drugs introduced?

A

Because once a new drug is marketed a bunch of new ones are made which are basically the same with a couple changes in the chemical structure

31
Q

What are the 4 processes that occur after a drug has been taken?

A
  1. Absorption
  2. Distribution (often termed redistribution)
  3. Distribution (often termed redistribution)
  4. Excretion
32
Q

For any routes of administration what must a drug be able to do to exert an effect?

A

It must be able to cross biological membranes

33
Q

What are the 3 mechanisms available for termination of drug action?

A
  1. Redistribution
  2. Excretion
  3. Conversion to water soluble inactive products in the liver
34
Q

Explain redistribution/distribution of a drug. Explain with an example of a drug

A
  • Drug = Thiopental (Short acting barbiturate anesthetic
  • Puts patients to sleep
  • When given intravenously there is immediately a high concentration of thiopental in the blood and then a lower amount in the muscle/fat
  • After a few minutes the concentration in the blood decreases and the concentration in the muscle/fat increases
  • With the concentration of the drug in the blood falling, the drug will leave the brain and move into the blood.
35
Q

How are most drugs excreted?

A

Through the kidney

36
Q

A drug that is ________________ is readily excretal by the kidney

A

Water soluble

37
Q

How are drugs filtered by the kidney eliminated?

A

In the urine

38
Q

A majority of drugs are very poorly _____________ and cannot be ________________

A

Water soluble, excreted by the kidney

39
Q

A majority of drugs are water soluble

A

The majority of drugs are very poorly water soluble

40
Q

What happens when a drug cannot be excreted by the kidney and is not water soluble

A

The liver take over and uses enzymes and converts these things into water soluble compounds

41
Q

In the liver, there are enzymes available for ________________ to more ___________ products which may be excreted by the __________

A

Converting drugs, Water soluble, Kidney

42
Q

In general, the mechanisms in the liver which ____________ to __________________ also result in the ___________ of drugs.

A

Convert drugs, Water soluble products, inactivation

43
Q

Why have chemicals such as PCBs and insecticide DDT been banned in some countries?

A

Because they are only very slowly converted to more water soluble products by the liver and therefore, they accumulate in the body

44
Q

What is the definition of drug interaction?

A

When one drug changes the pharmacological effect of a second drug

45
Q

Why Should the tetracycline group of antibiotics and antacids containing calcium, magnesium or aluminum not be mixed?

A

Drug interaction –> these drugs will combine and they will form a complex which cannot be absorbed into the blood