Medicines and Food

• The timing of medicine administration in relation to food is not important for most medicines. In general, patients should be advised to take their medicines consistently at the same time with respect to meals.
• Adherence to medicines is a primary determinant of treatment success.
  • Poor adherence is common, especially with complex medicine regimens.
  • Increasing complexity by restricting patients to administration times in relation to food may adversely affect their adherence, e.g., instructions to take on an empty stomach may be particularly problematic.
• Advice about food should be limited to those few medicines for which any food interactions are clinically relevant, or where the timing of food significantly impacts the incidence of adverse reactions.
  • There is not good evidence that taking a medicine with food reduces gastrointestinal adverse effects. However, this strategy may be offered to patients who have troublesome gastrointestinal adverse effects, with advice to tell their doctor if symptoms continue.
• Specific recommendations for dosing in relation to food are often included in prescribing and consumer information. There can be discrepancies in the advice given by different sources, often due to information not being updated as new evidence becomes available.

  Factors to consider	Clinically relevant examples	Advice
  Pharmacokinetic
  Absorption Is it significantly decreased or increased by food?	Food decreases absorption alendronic acid, risedronate	Take at least 30 minutes before food
  	Food increases absorption isotretinoin itraconazole (capsules)	Take with food
  	Food decreases or increases absorption buspirone tacrolimus	Take at the same time in relation to food
  	Calcium decreases absorption ciprofloxacin, norfloxacin	Don’t take with milk or yoghurt
  Metabolism Is it significantly decreased or increased by food?	Grapefruit inhibits first pass CYP3A gut metabolism atorvastatin, simvastatin ciclosporin felodipine	Avoid grapefruit and its juice
  Pharmacodynamic
  Does food alter the therapeutic effect of the medicine?	Foods high in vitamin K, e.g. leafy green vegetables can reduce INR warfarin	Avoid large, sudden changes in diet Abstinence is not required
  	Liquorice can have mineralocorticoid activity (fluid retention, hypertension, hypokalaemia) antihypertensives corticosteroids	Avoid large amounts of liquorice (>20 g/day)
  	Food increases efficacy acarbose pancreatic enzymes calcium or aluminium salts when used as phosphate binders	Take with food
  	Food decreases efficacy mouthwashes oral antifungal drops, gels or lozenges	Take after food to ensure maximum contact time
  Does the medicine alter the effect of food?	Tyramine-containing foods can cause hypertensive crisis non-selective MAOIs, e.g. tranylcypromine	Avoid tyramine-containing foods, e.g. aged cheese, meat or yeast extracts, pickled fish, broad bean pods, sauerkraut, salami, protein drinks
  Adverse effects
  Are they reduced by food?	Food reduces risk of hypoglycaemia sulfonylureas	Take with food
  	Food may reduce gastrointestinal upset amoxicillin+clavulanate azathioprine corticosteroids digoxin metformin metronidazole NSAIDs	Try taking with food if gastrointestinal adverse effects occur

Topic Code: 93256

must be prescribed or recommended by a consultant.