Page 49 - Community pharmcy practice E-book 2025

01/11/2025, 22:08 Medication Errors & Constipation Management

Summary of Key Interactions

Drug Combination Potential Outcome
NSAIDs and warfarin Enhanced bleeding
NSAIDs and methotrexate Methotrexate toxicity
warfarin and erythromycin Enhanced bleeding
ACE inhibitors and potassium/potassium-sparing diuretics Risk of hyperkalaemia
verapamil and β blockers Risk of asystole
digoxin and amiodarone Risk of digoxin toxicity

Drug/Food Interaction

Food interactions may predictably involve absorption interactions but also effects on
cytochrome P450 isoenzymes, leading to metabolic interactions.

Drug/Food Interaction Examples

monoamine oxidase inhibitor antidepressants (MAOIs) and tyramine-
containing foodstuffs (cheese). Risk of life-threatening hypertensive crisis

Grapefruit juice is a potent inhibitor of cytochrome P450 3A4 and causes
clinically relevant interactions with a number of drugs including simvastatin
and atorvastatin, thereby increasing the risk of statin-induced adverse
reactions such as myopathy and myositis.

Clinical Significance

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