Introduction to clinical pharmacology Flashcards Preview

E: Quantitative Pharmacology > Introduction to clinical pharmacology > Flashcards

Flashcards in Introduction to clinical pharmacology Deck (42):
1

Quantal?

All or nothing

unlike scalar where is more linear

2

ED50

The median effective dose

3

TD50

Median toxic dose

4

LD50

Median lethal dose

 

AS26

5

Drug interactions

Can be harmful or beneficial.

Several drugs are often prescribed simultaneously.

 

6

What two things does adverse drug interactions involve?

Pharmodynamic

Pharmokinetic 

7

How increase the chance of having an adverse effect?

Increase the number of drugs used.

8

Pharmacodynamic?

Drug A modifies the pharamcological effects of drug B without altering its conc. in tissue fluid.

 

9

Pharmokinetics?

Drug A modifies the concentration of drug B that reaches its site of action.

 

10

What 4 things can cause changing in pharmokinetics?

Absorption

Distribution

Metabolism 

Excretion 

11

Changes in distribution?

Drugs bound to plasma proteins can be displaced by a second drug.

Increasing their free concentration level.

Increase in elimination

12

Changes in absorption?

Drugs that effect the rate of emptying of the stomach will effect absorption.

 

13

Changes in metabolism?

Induction of hepatic enzymes by drugs can decrease the efficacy of the metabolism of other drugs by the same enzyme.

 

14

Changes in excretion?

Drugs may share a common tansporter.

15

Example of an interaction between warfarin and flucanazole?

Fluconazole inhibits the cytochrome P450 enzymes

Cytochrome P450 enzymes metabolises warfarin.

Increase the effects of warfarin

16

Variability in drug response occurs because?

  • The plasma concentration is higher than desired.
    • Excessive dosing or decreased clearance.
  • Plasma concentration is lower than desired.
    • Dose too low
    • Increased clearance

17

Competitive enzyme inhibition?

Higher Km

Same Vmax

18

Non-competitive enzyme inhibition?

Same Km

Lower VMAX

19

Enzyme induction?

Same Km

Higher VMAX

 

20

CYP4?

Major drug metabolite in human

21

Liver disease?

May alter the response to drugs in several ways.

Prescribed drugs should be kept to a minimum

22

Impaired drug metabolism?

Important in severe disease.

Particularly for extensively metabolismed drugs with low TR.

 

23

When is drug dosage adjusted for?

High Cl drugs (Affected by blood flow and enzyme capacity).

Low Cl drugs (affected by enzyme capacity only)

24

Impaired metabolism occurs more predictably with?

Chronic disease than acute disease

25

Name the 4 altered response to drugs in the presence of liver disease?

  1. Reduced synthesis of plasma proteins
  2. Reduced synthesis of clotting factors
  3. Impaired excretion of drugs eliminated by the bile.
  4. Altered pharmacodynamic

26

Reduced synthesis of plasma proteins 

In severe disease.

Causes increased toxicity of highly protein bound drugs with low TR.

27

Reduced synthesis of clotting factors?

Causes enhanced sensitivity to oral anti-coagulants.

28

Impaired excretion of drug eliminated by the bile?

Occurs in cholestasis

Were the flow of bile to the duodenum is compromised

29

Name the two types of altered pharmacodynamics?

  1. Hepatic encephalopathy
  2. Ascites

 

30

Heptaic encephalopathy?

Delerioration of brain function with severe liver disease.

Worsened by several drug classes

31

Ascites?

Accumulation of fluid in the peritoneal cavity associated with severe liver disease.

Worsened by drugs that cause fluid retention.

32

What does the level of renal function depend on?

The proportion of the drug eliminated by renal excretion and its toxicity.

33

Clearance of creatinine?

Is a measure of GFR

Reduced by renal impairment

34

Fu of 0.5 means?

That only 50% of the drg is excreted from the kidneys

35

How can you judge how much you have to change the drug dosage?

Equation

Rate of creatinine clearance and the fraction of drug that is excreted by the kidney.

AS27

36

3 BNF grades of renal impairment?

Mild

Moderate

Severe

37

Creatinine clearance for each grade?

Mild= 20-50ml/min

Moderate= 10-20ml/min

Severe= <10ml/min

38

The total daily maintenance dose can be reduced by 2 things?

Reducing the size of the individual doses

Increasing the intervals between doses

39

Dosage for children?

Dosing by body weight (or body surface area).

Alterered pharmacokinetics and pharmacodynamics in neonates requires special caution 

40

Neonates

First 30 days of life

41

Dosage for elderly?

Reduction in renal clearance.

Excrete drugs slowly.

Clearance of the drug is impaired in the elderly (ie they wont have high Fu)

42

Dosage for pregnancy?

Harmful effects on the embryo.

Main issue- teratogenicity.

Embryo at a high risk in the first couple of weeks in pregancy (when the mother doesnt know)

If it is orally absorbed, it can cross the placenta.

Benefits have to outweigh the risks