Pathogenetic Classification
Type A side effects: predictable and dose dependent
Definition: Exaggerated but otherwise normal pharmacological action of a drug given in the usual therapeutic doses. Side effects are predictable, usually dose dependent. Their prevalence and morbidity are high and the mortality usually low.
Possible causes:
- Pharmaceutical causes
- Drug quality
- Drug release
- Pharmacokinetic causes
- Drug absorption
- Drug distribution
- Drug elimination
- Drug receptors
- Homoeostatic mechanisms
- Neoplastic and teratological reasons
Type B side effects: unpredictable and not dose dependent
Definition: Totally aberrant that are not to be expected from the pharmacological actions of a drug when given in the usual therapeutic doses to a patient whose body handles the drug in the normal way. Type B reactions are often serious.
Possible causes:
- Pharmaceutical causes
- Pharmacokinetic causes
- Pharmacodynamic causes
- Genetic causes for abnormal response
- Immunological reasons for abnormal response
See A. Davies: Textbook on Adverse Effects of Drugs