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31/10/2025, 23:40 Community Pharmacy Practice - Course Materials
Type B (Bizarre) reactions
Unpredictable, uncommon, usually not related to the pharmacological actions of the drug.
Not dose dependent, host dependent factors important in pre-disposition (high susceptibility)
Idiosyncratic
"allergic" or "hypersensitivity reaction"
Anaphylactic reactions to penicillin, hepatotoxicity with sulfasalazine and malignant
hyperthermia after anaesthetics are examples.
All medicinal products contain excipients that may precipitate type B reactions.
Comparison between Type A and Type B
Associated with the pharmacology of the product Type A Type B
Predictable ✓ ✗
Dose related ✓ ✗
Common ✓ ✗
Serious ✓ ✗
✗ ✓
Type B : Allergic reactions
Some allergic reactions occur within minutes (even seconds) after the drug is given; most
serious
others may be delayed for hours or days.
Allergic reactions are manifested by a variety of signs and symptoms observed by the nurse or reported by the
patient.
Examples of some allergic symptoms include itching, various types of skin rashes, and hives
(urticaria).Other symptoms include difficulty breathing, wheezing, cyanosis, a sudden loss of
consciousness, and swelling of the eyes, lips, or tongue.
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