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Effects of Drugs on Nutrition
Dr Mollie van Zyl September 2011
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Drug –nutrient interactions are broadly divided into drugs that :
i) adversely affect nutritional status by : impairing the intake of food the absorption, metabolism and excretion of nutrients, and ii) conversely the adverse effect on drug metabolism by impairing their absorption and therefore their efficacy.
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Table 1 Examples of medication with specific dosing instructions
30min before food or on an empty stomach Phenoxymethylpenicillien Itraconazole Not to be taken with indigestion medication Ketoconazole Not to be taken with iron, zinc or antacid preparations Ofloxacin Levofloxacin Doxycycline Penicillamine Not to be taken with milk, iron, zinc or antacid preparations Ciprofloxacin Norfloxacin Tetracycline
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Amantadine Digoxin Fluoxetin Levodopa Lithium Metformin Penicillamine
Table 2 Drugs associated with anorexia or weight loss. Amantadine Digoxin Fluoxetin Levodopa Lithium Metformin Penicillamine Topiramate Nortriptyline
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Table 3 Drugs associated with weight gain.
Tri-cyclic antidepressants excluding nortryptiline Valproate Beta blockers Oral contraceptives Anti psychotics Steroids Anabolic steroids
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Table 4 Drugs commonly associated with nausea and vomiting.
Action on chemoreceptors in the GIT Cytotoxics Potassium Iron preparations Antibiotics Action at the chemoreceptor trigger zone Anaestetics Opiates Nicotine Levodopa Selective serotonin re-uptake inhibitors (antidepressants)
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Table 5 Drugs associated with decreased gastrointestinal motility.
Anticholinergic effect Tricyclic antidepressant Oxybutynin Propantheline Opiates Morphine Codeine Ondansetron
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Table 6 Drugs associated with diarrhoea.
Erythromycin Metoclopramide and Domperidone Broad spectrum antibiotics Misopristil Proton pump inhibitors Antivirals and anti retrovirals Lamivudine, tenovir Magnesium salts Iron Lithium (sign of toxicity) Digoxin (sign of toxicity) Acarbose Metformin Colchicine (sign of toxicity)
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Table 7 Drugs associated with dry mouth.
Anticholinergic drugs Sedatives Atropine, Oxybutynin, hyoscine, benztropine Diazepam, temasepam Antidepressants and antipsychotic drugs Muscle relaxants SSRI citalopram, fluoxetine, paroxitine, venlafaxine Orphenadrine Tricyclic amitryptiline, imipramine Analgesics Codeine, methadone, tramadol, buprofen Diuretics Furosemide, chlorothiazide Antihistamines Astemisole, chlorphenamine Antihypertensives ACEI Captopril, enalapril, lisinopril loratidine Clonidine, Methyldopa Carbamazepine, carbidopa, levodopa, ipratropium
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Table 8 Drugs associated with ageusia, hypogeusia.
ACEI Benzodiasepines Metformin Amphetamines Cephalosporins Methotrexate Amiloride Claritromicin Metochlopramide Amphoteracin Clopidogrel Nifedipine Ampicillin Corticisteroids Spironolactone Asperin Diltiazem Sucralfate Azathioprin Furosemide Tricyclic antidepressants Baclofen Levodopa Venlafaxine
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Table 9 Drugs associated with dysgeusia.
Bitter taste Metalic taste Asperin Allopurinol Carbamasepine Captopril Clarithromycin Ethambutol 5 Fluoro-uracil Litium Isosorbide mononitrate Metformin Levodopa Metronidazole Risperdal Sartan antihypetensives Sulphasalazine Nifedipine
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Table 10 Drugs associated with olfactory disturbances.
ACEI Cocaine Methotrexate Amikacin corticosteroids Pentamidine Amiodarone Decongestants Quinolones Amphetamine Doxycycline Statins Amoxillin Gemfibrozil Streptomycin Beta blockers Gentamycin Sumatriptan Calcium channel blockers Isotretanoin Terbinafine Chlorhexidine Levodopa Tobacco
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Table 12 Absorption of selected drugs that may be affected by food.
Drugs with reduced absorption Example Antibiotics Amoxillin, Penicillin ACEI Captopril Ethanol Alcoholic beverages Anti Parkinson’s Levodopa Bronchodilator Theophylline Drugs with delayed absorption Anti ulcer Cemetidine NSAIDS Diclofenac Antiarrythmic Digoxin Anti diabetc Glipizide Antibiotic Metronidazole Drugs with increased absorption Nitrofurantoin Anti anxiety Diazepam Anti hypertensive Hydralazine Antimanic Lithium Diuretic Chlorothiazide
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Minerals E.g. Ironsulphate
Table 13 Impaired drug absorption Nutrient Mechanism Adverse effect Minerals E.g. Ironsulphate Forms compounds with antibiotics –tetracyclines, ciprofloxacin and reduce absorption Reduced efficacy Vitamins E.g. Vitamin K Inhibits the effect of Coumadin (Warfarin) increasing production of Factor II, IIV, IX and X Decrease clotting time Indolic compounds E.g. Broccoli, cauliflower Induce enzymes e.g. NADP, glucuronyltransferases Decrease efficacy of drugs – increase metabolism Flavones in citrus Inhibit enzymes lipoxygenase and cyclo-oxygenase Î Inflammatory response - swelling, headaches Grape fruit Inhibits cytochrome P450, affects the intestinal transporter protein Alter bioavailability and pharmacokinetics of CCB, statins Cranberry juice Interacts with coumadin Increase INR , increase risk of bleeding Vitamin C Increase urinary acidity , decrease elimination of salicylates e.g aspirin Ulcerogenic
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