Page 62 - COMMUNITY PHARMACY PRACTICE
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Type A (Augmented ) reactions
• Predictable, common and related to Pharmacological action of the drug
• About 80% of all adverse drug reactions are type A and for most
prescription this type of reaction is described in handbooks such as the
physician’s desk reference
• Dose dependent, can be alleviated by a dose reduction
• E.g. Bleeding with anticoagulants, bradycardia with beta blockers,
headache with nitrates, postural hypotension with prazosin
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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.
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