Drug Absorbtion 1 Flashcards

1
Q

Define Pharmaceutical Process?

A

Getting the drug into the patient

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2
Q

What is it called “getting the drug to the site of action in the patient”?

A

The pharmacokinetic process

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3
Q

What is the pharmacodynamic process?

A

Producing the correct Pharmocological effect with the drug.

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4
Q

{What is the therapeutic process?

A

Producing the intended therapeutic response?

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5
Q

What determines pharmacokinetics?
[ADME}

A

Absorption
Distribution
Metabolism
Elimination

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6
Q

Define Absorption:

A

Process of movement of unchanged drug from site of administration to sytemic circulation.

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7
Q

Try name 9 drug application routes. Go on i fucking dare you

A

Oral
Subcutaneous/Intramuscular
Inhalation/nasal
Transdermal (skin patches)
IV
Topical (creams etc)
Sublingul (under tongue)
Rectal

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8
Q

Define therapeutic range:

A

The range of blood [drug] over which a drug is active

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9
Q

What happens if drug conc. is above or below the therapeutic range?

A

If its above the range toxicity occurs
If its below the range theres insufficient pharmacological action

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10
Q

Define Therapeutic Index (TI):

A

A comparison of the drug conc. level that causes the therapeutic effect against the amount that causes toxicity.

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11
Q

What two things must you consider concernin the rate of oral absorption?

A

Amount of drug entering systemic circulation and speed at which it happens

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12
Q

What is Tmax?

A

The time to peak drug conc. in systemic circulation

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13
Q

What is Cmax?

A

The peak drug conc. in systemic circulation

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14
Q

What is the AUC?

A

The area under a drug conc vs time curve.
I.e. the amount of drug reaching circulation

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15
Q

How does increasing the dose affect Tmax & Cmax?

A

Increasing the Dose has no effect on Tmax but increases Cmax.

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16
Q

Define Bioavailability?

A

Amount of Drug reaching circulation & available for action

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17
Q

What method of drug administration has 100% bioavailability?

A

Intravenous Drugs have 100& bioavailability.

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18
Q

What 4 factors effect Bioavailability?

A
  • Formulation
  • First pass metabolism
  • Gastrointestinal effects
  • Ability of drug to pass physiological barriers.
19
Q

How does formulation affect bioavailability?

A

Some drugs are prepared for slow release

20
Q

What 3 gastrointestinal effects alter bioavailability?

A
  • Illness & Dsease
  • Gut Motility
  • Food
21
Q

What 3 areas affect the ability of a drug to pass physioloical barriers?

A
  • pH & Ionisation
  • Lipid Solubility
  • Particle Size
22
Q

Define First pass metabolism?

A

The amount of drug metabolised by the gut before it is absorbed into systemic circulation

23
Q

What does passive diffusion rely on?

A

Lipid solubility
Degree of ionisation

24
Q

Why does drug ionisation affect passive diffusion?

A

Only unionised drugs can pass through membranes as ionised arnt lipid soluble

25
Q

What does the degree of ionisation rely on?

A

Local pH
i.e. an acidic drug will ionise in an alkaline enviroment

26
Q

What is the henderson-hasselbach equation used for?

A

The relationship between local pH and drug ionisation

27
Q

To what degree do pH changes affect drug ionisation?

A

Small pH changes can cause significant changes to drug ionisation & therfore diffusion rates.

28
Q

What is the lipid-water partition coefficient?

A

The ability of a drug to diffuse across a lipid barrier
(ratio of drug dissovled in lipid vs water phase when in contact)

29
Q

Exapli active absorption

A

Active absorption is unusual, occurs aainst the conc. gradient, is specific and requires carriers/energy.

30
Q

Example of drugs moved by active absorption:

A

Iron, potassium, sodium, calcium
Also levodopa uptake by the brain

31
Q

Explain Facilitated Diffusion:

A

Along conc. gradient
Needs carriers but not energy
Mizxed order kinetics

32
Q

Examples of drugs moved by facilitated diffusion:

A

Monosaccharides
AminoAcids
Vitamins

33
Q

What drives filtration/bulk flow across membranes?

A

Hydrostatic or osmotic pressure difference across the membrane

34
Q

How does Gut motility affect the rate of dru absorption?

A

The faster the gastric activity the faster the drug reaches the site of absorption

35
Q

What effects can food have on drug absorption?

A

Food can enhance or impair absorption of some drugs

36
Q

How can illness efect drug absorption?

A

Malabsorption can impair or inhance drug absorption rates
(e..g caeliacs disease)

37
Q

Define First pass metabolism:

A

Amount of drug metabolised prior to reaching the site of absorbtion

38
Q

How is drug metabolised in first pass metabolism?

A

By acids/enzymes in the gut lumen
By metabolic enzymes in the gut wall
By Hepatic enzymes in the liver

39
Q

What affects level of first pass metabolism:

A

The drug
Diseases
The person

40
Q

Descrive Intravenous drug administration:

A
  • 100% bioavailability
  • Avoids 1st pass metabolism
41
Q

Describe Topical drug Administration:

A
  • Can achieve local or systemic effects
  • Can achieve controlled, sustained doses of drugs
  • Avoids 1st pass metabolism
42
Q

Descrive Inhalation drug administration:

A
  • Drug delivered directly to site
  • Rapid effect
  • Small doses needed
  • Reduced adverse effects
  • Metabolised in lungs so only 5-10% is absorbed. (little systemic effecT)
43
Q

Describe the Hendersen-Hasselbach equation:

A

pH = pKa + log10 (ConjugateBase/UndissociatedAcid)