Principles of Drug Toxicity Flashcards Preview

Vet - notes > Principles of Drug Toxicity > Flashcards

Flashcards in Principles of Drug Toxicity Deck (19):
1

Therapeutic index =

Effective dose (50%)/ Toxic dose (50%)
Risk Benefit Analysis done before drug is authorized

2

Why do we see drug toxicity in veterinary patients?

use of drugs in untested species
mistakes in dose calculation
multiple drugs in use

3

adverse drug reactions (ADR) - Type A reactions

Predictable from knowledge of mechanism of action of the drug
Beta blockers causing bradycardia
ACE inhibitors causing acute renal failure
Sulphonylurea drugs causing hypoglycaemia

4

adverse drug reactions (ADR) - Type B reactions

Not related to the mechanism of action of the drug therapeutically – non/predictable

5

Factors that enhance ADR

Physiological Factors - Age, breed, gender
Disease status - Hepatic, renal and cardiovascular
Concomitant use of other drugs

6

differences in physiology in neonates

decr gut motility, underdeveloped mucosa + flora
incr total body water
Immature liver enzymes
Decr GFR

7

drug in neonates - Empirical guidelines

Avoid if possible
drugs with wide therapeutic indices if possible
formulation that allows accurate dosing
Weigh the animal accurately

8

Examples of toxicities specific to neonates

Fluoroquinolones – damage to articular cartilage
Tetracyclines – discolouration of teeth

9

Increased risk of ADRs in geriatrics because

Smaller body size
Poor nutritional status
Presence of multiple disease processes
Altered compliance
Age related changes in organ function (e.g. renal function)

10

why does decr renal function incr chance of ADR

decr clearance of drugs via the kidneys

11

Monensin toxicity in horses

Clinical signs - neuronal, skeletal and cardiac muscle effects of ionophores
susceptibility d/t low first pass metabolism in horses -systemic bioavailability of this drug much higher than in sheep.

12

Pyrethrum insecticide treatment of cats

more sensitive to the toxic effects flea products for dogs
d/t ineffective metabolism
hyper-excitability leading to convulsions
incidence of accidental toxicity is high, despite clear labels saying toxic to cats

13

Type A examples - Beta blockers

bradycardia

14

Type A examples - ACE inhibitors

acute renal failure

15

Type A examples - Sulphonylurea drugs

hypoglycaemia

16

idiosyncratic type B reactions - Chloramphenicol

aplastic anaemia

17

idiosyncratic type B reactions - Phenylbutazone

agranulocytosis

18

idiosyncratic type B reactions - Phenytoin

hepatitis

19

Detection of idiosyncratic reactions

Less than 1 in 2000 patients
not detected by pre-registration clinical trials
post-licensing surveillence scheme needed