Pharmacokinetics

Question 1

Pharmacokinetics?

Answer 1

WHAT DOES THE BODY DO TO THE DRUG

Question 2

What does pharmacokinetics determine? (3)

Answer 2

1) How much drug reaches drug targets
2) How quickly a drug begins to have an effect (onsent of action)
3) Duration of effect

Question 3

Routes of drug administration (5)

Answer 3

Oral = (e.g tablets, capsules, liquids)
Inhalation = (e.g nebulisers, inhalers)
Topical = (e.g creams)
Injection = (3 types)
INTRAVENOUS = into systemic circulation 
INTRAMUSCULAR = into muscle
SUBCUTANEOUS = just under skin 
Across Mucus Membrane = (e.g buccal, sublingual, rectal, vaginial)

Question 4

What determines pharmacokinetics? (4)

Answer 4

Absorption
Distribution
Metabolism
Excretion

Question 5

Bioavailability?

Answer 5

Fraction of administered drug that reaches systemic circulation unchanged

Question 6

Oral route (what effects bioavailability?)

Answer 6

Stability in gut contents (e.g not degraded by acid)
Absorption across gut wall
Degree of 1st pass metabolism (after portal system)

Question 7

Influences of absorption in the gut? (3)

Answer 7

1) Surface area (S.I > stomach)
2) Gastric emptying (food in stomach = longer before empires into S.I)
3) Gastric motility (Increased gut motility = decreased time in contact with small intestine)

Question 8

route of drug distribution

Answer 8

BLOODSTREAM → INTERSTITIUM → TISSUES + CELLS

Question 9

Volume distribution (defintion)

Answer 9

theoretical volume in which (Q) administered dose would need to be diluted in to give the initial observed plasma conc (C0)

Question 10

High vs Low volume distribution

Answer 10

High Plasma conc, low peripheral tissue conc = LOW Vd (e.g aspirin + warfarin)
Low Plasma conc, high peripheral tissue conc = HIGH Vd

Question 11

Decreased drug metabolism (slow acytelators, reduced liver function)

Answer 11

Increased plasma drug conc (stays in blood)

Increased biological response

Question 12

Increased drug metabolism (fast aceytlators)

Answer 12

Reduced plasma drug conc

Reduced biological response

Question 13

Effects of reduced excretion

Answer 13

Increased plasma drug conc

Increased biological response

Question 14

Polymorphism of drug targets

Answer 14

Different variants of drug targets
Different sensitivities to drugs
May need more / less to have the same effect

Question 15

Polymorphism of drug metabolism enzymes

Answer 15

gene mutations → enzyme has lower/higher activity

Response + toxicity varies depending on whether they are fast / slow metaboliser