13)Adverse effect of drugs

Question 1

Adverse effects

Answer 1

Any undesirable/unintended consequence of drug administration

• ALL drugs can produce an adverse effect ⇢ benefits must outweigh risk when prescribing drugs
• They can develop shortly, after prolonged use, or after stoppage of drug

Question 2

Classes of adverse reactions

Answer 2

Type A - Augmented

• occurs in everyone if enough of the drug is given due to excess of normal, predictable, dose-related, pharmacodynamic effects

Type B - Bizarre

• Only in some people
• Not part of normal pharmacology of drug + not dose related
• Includes unwanted effects due to ⇢ inherited abnormalities + immunological processes

Type C - Chronic ⇢ Due to long term exposure

Type D - Delayed ⇢ Occurs following prolonged exposure

Type E - Ending of use ⇢ Discontinuation of chronic therapy is too abrupt

Question 3

Causes of adverse effects

Answer 3

• Patient may be predisposed ⇢ age, genetics, allergies, disease, lifestyle
• Mechanism of drug (eg anti-cancer drugs = cytotoxic in nature)
• Ingredients of a formulation (eg colouring, flavouring, sodium content)

Question 4

Severity of adverse effects

Answer 4

• Minor ⇢ no therapy/antidote required
• Moderate ⇢ Requires change in drug therapy, specific treatment or prolonged hospital stay
• Severe ⇢ Potentially life threatening causing permanent damage
• Lethal ⇢ Directly/indirectly causes death

Question 5

Management of adverse effects

Answer 5

• Avoid inappropriate use of drugs = appropriate dose, route + frequency
• Consider previous history of drug’s adverse effects
• Check patient history of allergies
• Use correct administration techniques