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Flashcards in 1 Pharmacokinetics and 2.1 Pharmacodynamics Deck (20):
1

What is the Volume of Distribution?

The distance that a drug will be distributed into the tissues and fluid compartments.
It is proportional to the half life of the drug

2

What organs are involved in 1st Pass Drug Metabolism? How?

The Liver - CYP450 enzymes
The Gut Wall - drugs can increase efflux
The Gut Lumen - gastric acid, grapefruit juice

3

What 2 things affect the distribution of a drug?

Protein Binding
Volume of Distibution

4

What factors can change the distribution of a drug to tissues?

Regional Blood Flow
Disease States
Drug Interactions
Lipid Solubility
Receptor Types
Active Transport

5

What can displace a drug from being protein bound?

Pregnancy
Low Albumin
Other Drugs
Renal Failure

6

What are CYP450?

Enzymes in the liver which catalyse the metabolism of some drugs
Not all types are present in everyone, causes heterogeneity to drugs

7

What things inhibit CYP450?

Sulphonamide
Grapefruit Juice
Cranberry Juice
Omeperazol
Isoniazide

8

What things induce CYP450?

St Johns Wort
Alcohol
Rifampicin
Pheyltoin
Barbituates

9

Which Drugs should be monitored?

Narrow Therapeutic Window
Long Half Life
Patients with Renal, Hepatic Failure

10

What is multi-compartment modelling?

When we look at half life and volume of distribution we are normally assuming only one compartment.
There is a way of seeing how drugs will act in many compartments as they'll each have their own elimination rates

11

What is the Fluid distribution of the body?

5L in Plasma (12%)
14L in the Interstitium (33%)
23L in ICF (55%)

12

What is the difference between specificity and selectivity?

Specificity is how specific it is to one type of receptor
Selectivity is how selective it is to the target - side effects

13

How can drugs interact with another's Pharmacokinetics?
ADME

Absorb: drugs can interact with gut motility/flow rate
Distribute: displace from proteins
Metabolise: Affect CYP450
Eliminate: Protein binding, tubular secretion, pH, age

14

What classes of drugs have common interactions?

Antidepressants
Anticonvulsants
Antibiotics
Antiarrhythmic
Anticoagulants

15

Which diseases can interact with drug metabolism?

Renal
Hepatic
Cardiac

16

How does Cardiac disease interact with metabolism?

Decreased CO so reduced organ perfusion
Increased interaction with hypotensive drugs.
Oedema leads to reduced absorption

17

How does Renal disease interact with metabolism?

Decreased GFR so Reduces Clearance
Electrolyte disturbances
Nephrotoxins do further damage

18

How does Hepatic disease interact with metabolism?

Decreased Protein production
Decreased enzyme activity

19

What increases the risk of ADRs?

Age
Co-morbidities
Polypharmy
Ignorant Prescribing
Drugs with Narrow TIs

20

What causes heterogeneity with responses to drugs?

Genetic Factors - Enzymes
Age
Sex
Weight
Dose, Route, Administration
General Health
Other Drugs