Antacids Dairy products

Tetracycline Antacids, dairy products, oral iron, sucralfate, zinc sulphate Reduced absorption. 

Adverse effects with the tetracyclines include gastrointestinal upset drug interactions with dairy products, antacids, and iron and phototoxicity. Minocycline can also cause vestibular complications (headache and dizziness) and skin discoloration that is not typical with tetracycline and doxycycline.16... 

Absorption from the gastrointestinal tract can be affected by other drugs and by food. Aluminum, calcium, and magnesium ions in antacids or dairy products form insoluble chelates with all tetracyclines and inhibit their absorption. Food inhibits tetracycline absorption but enhances doxycycline absorption food delays but does not diminish metronidazole absorption fatty food enhances griseofulvin absorption. 

Uses Broad-spectrum antibiotic Action Bacteriostatic protein synth Spectrum Gram(+) Staphylococcus sp, Streptococcus sp Gram(-) H. pylori Atypicals Chlamydia sp, Rickettsia sp, Mycoplasma sp Dose Adults. 250-500 mg PO bid—qid Peds > 8 y. 25-50 mg/kg/24 h PO q6-12h i w/ renal/hepatic impair, w/o food preferred Caution [D, +] Contra PRG, antacids, w/ dairy products, children <8 y Disp Caps 100, 250, 500 mg tabs 250, 500 mg PO susp 250 mg/5 mL SE Photosens, GI upset, renal failure, pseudotumor cerebri, hepatic impair Interactions T Effects OF anticoagulants, cligoxin effects W/ antacids, cimeticline, laxatives, penicillin, Fe supl, dairy products effects OF OCPs EMS T Effects of anticoagulants monitor for signs of electrolyte disturbances and hypovolemia d/t D ... 

Tetracyclines mainly differ in their absorption after oral administration and their elimination. Absorption after oral administration is approximately 30% for chiortetracycline 60-70% for tetracycline, oxytetracycline, demeclocycline, and methacycline and 95-100% for doxycycline and minocycline. A portion of an orally administered dose of tetracycline remains in the gut lumen, modifies intestinal flora, and is excreted in the feces. Absorption occurs mainly in the upper small intestine and is impaired by food (except doxycycline and minocycline) by divalent cations (Ca2+, Mg2+, Fe2+) or Al3+ by dairy products and antacids, which contain multivalent cations and by alkaline pH. Specially buffered tetracycline solutions are formulated for intravenous administration. 

Calcium carbonate(eg, Turns, Os-Cal) is less soluble and reacts more slowly than sodium bicarbonate with HC1 to form carbon dioxide and CaCl2. Like sodium bicarbonate, calcium carbonate may cause belching or metabolic alkalosis. Calcium carbonate is used for a number of other indications apart from its antacid properties (see Chapter 42 Agents That Affect Bone Mineral Homeostasis). Excessive doses of either sodium bicarbonate or calcium carbonate with calcium-containing dairy products can lead to hypercalcemia, renal insufficiency, and metabolic alkalosis (milk-alkali syndrome). 

Tetracyclines Dairy products high in calcium ferrous sulfate or antacids Impaired absorption of tetracycline... 

Interactions. Dairy products reduce absorption to a degree but antacids and iron preparations do so... 

Drug interactions The bioavailability of tetracyclines is significantly deaeased when administered with antacids containing aluminum, calcium, or magnesium, with iron-containing products, or with food. Food or dairy products do not affect the bioavailability of doxycycline or minocycyline. 

Clinically important, potentially hazardous interactions with acitretin, aluminum hydroxide, amoxicillin, ampicillin, antacids, bacampicillin, betamethasone, bismuth, bromelain, calcium, carbenicillin, cholestyramine, doxacillin, corticosteroids, dairy products, dicloxacillin, didanosine, digoxin, food, glidazide, iron, isotretinoin, methicillin, methotrexate, methoxyflurane, mezlocillin, nafcillin, oxacillin, penicillins, piperacillin, retinoids, rocuronium, strontium ranelate, sucralfate, ticarcillin, vitamin A, zinc... 

Concomitant use of tetracycline with antacids containing aluminum, calcium, or magnesium decreases absorption of oxytetracycline (because of chelation) concomitant use with food, milk or other dairy products, oral iron products, or sodium bicarbonate also impairs oral absorption. 

Gastrointestinal Ah tetracychnes can produce GI irritation, typically after oral administration. Tolerabihty can be improved by administering the drug with food, but tetracyclines should not be taken with dairy products or antacids. Tetracychne has been associated with esophagitis and pancreatihs. Pseudomembranous colitis caused by overgrowth of C. difficile is a potentially life-threatening complication. 

The patient should not be given antacids containing aluminum, calcium, or magnesium, laxatives, iron products, food, or milk or other dairy products for 1 hour before or 2 hours after tetracycline is administered. 

As tetracyclines have moderate to high lipophilic properties, the poor bioavailability associated with oral administration is somewhat surprising. Papich and Riviere suggest that causes may be multifactorial. As zwitterions, they are mainly ionized at pHs within GIT liquor. Moreover, feed reduces bioavailability, and tetracyclines chelate with polyvalent cations. Oxytetracycline absorption has been shown, experimentally, to be reduced by feed, dairy products, Ca +, Mg +, Al +, and Fe + ions and antacids. Even though doxycycline has a similar structure, affinity for metals is different from that of oxytetracycline with greater affinity for zinc and less for calcium. 

The proposed reason for these changes is that the calcium in milk and yoghurt or other dairy products combines with the ciprofloxacin and norfloxacin to produce insoluble chelates. Compare also Quinolones -i-Antacids or Calcium compounds , p.328. 

Hypercalcaemia, alkalosis and renal insufficiency (milk-alkali syndrome) can develop in patients taking antacids with calcium-containing substances, including dairy products. 

Food, dairy products and calcium compounds markedly reduce the absorption of strontium ranelate, and administration should be separated by at least 2 hours. Aluminium and magnesium antacids only slightly reduce strontium ranelate absorption. Strontium ranelate is predicted to reduce the absorption of the quinolones and the tetracyclines, and strontium should be stopped during courses of these antibacterials. Vitamin D does not affect strontium ranelate bioavailability. 

Taking your antibiotic with food may help reduce this sick feeling. Ciprofloxacin and doxycycline should not be taken within 2 hours ol taking antacids. Ciprofloxacin and doxycycline should not be taken with dairy or calcium-fortified products (such as ice cream or calcium-fortified orange juice). 

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