Tetracyclines Dairy products

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

TETRACYCLINES DAIRY PRODUCTS 1 antibiotic levels 1 absorption (due to the calcium content of dairy produce) Separate doses by at least 2 hours... 

Tetracycline Dairy products Impaired drug absorption... 

For detection residue amounts of tetracyclines in dairy products widely used methods FIPLC, immunoaffinity chromatography, kinetic spectrophotometry, which are expensive and complicated. 

Tetracyclines. It is important to give the tetracyclines on an empty stomach tetracyclines are not to be taken with dairy products (milk or cheese). The exceptions are doxycycline (Vibramycin) and minocycline (Minocin), which may be taken with dairy products or food. The nurse should give clindamycin with food or a full glass of water. The nurse can give troleandomycin and clarithromycin without regard to meals. All tetracyclines should be given with a full glass of water (240 mL). 

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. 

Mechanism of Action A tetracycline antibacterial that inhibits bacterial protein synthesis by binding to ribosomal receptor sites also inhibits ADH-induced water reabsorption. Therapeutic Effect Bacteriostatic also produces water diuresis. Pharmacokinetics Food and dairy products interfere with absorption. Protein binding 41 %-91%. Metabolized in liver. Excreted in urine. Removed by hemodialysis. Half-life 10-15 hr. 

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

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. 

Doxycycline can cause nausea, vomiting, and diarrhea. The bioavailability of doxycycline is reduced if coadministered with multivalent ions such as iron or magnesium. However, unlike tetracycline, it can be administered with food and dairy products. In addition, patients taking tetracyclines may experience photosensitivity, especially if they are fair skinned. Patients taking tetracyclines should avoid prolonged exposure to sunlight. 

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. 

Chemical interactions in the gastrointestinal tract between nutrients and drugs may considerably reduce the absorption of some drugs calcium ions from dairy products form insoluble and therefore nonabsorbable complexes with the antibiotic tetracycline. On the other hand, certain drugs are irritants to the gastrointestinal tract (nonsteroidal antiinflammatory drugs and potassium chloride tablets) and must be ingested with food. 

Tetracyclines also bind to the 30s subunit of ribosomes. They are active orally, but uptake is decreased by the calcium ions in dairy products, so they should not be taken together. 

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. 

After oral dosing, doxycycUne and minocycUne are almost completely absorbed and have half-lives of 16-18 hours they therefore are administered less frequently and at lower doses than tetracycline, oxytetracycUne, or demeclocycUne. Plasma concentrations are equivalent whether doxycycUne is given orally or parenteraUy. Food, including dairy products, does not interfere with the absorption of doxycycUne or minocycUne. 

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. 

Despite the fact that a plethora of dietary factors could, and will, affect the absorption characteristics of phytochemicals, this area has not been systematically explored. One reason might be the complexity of dietary factors and their interactions that could affect absorption. A nonexhaustive list would include the volume and composition of the food consumed, pH, caloric density, viscosity, nutrients (carbohydrates, protein, fat, fibers), alcohol, caffeine, and the presence of other phytochemicals. Such dietary factors affect the functional status, motility, and acidity of the gastrointestinal tract in a complex manner and modify the physicochemical properties, formulation, and dissolution characteristics of the compound of interest. Calcium in dairy products, for example, has the potential to chelate tetracyclines and fluoroquinolones and, thereby, reduce their bioavailability and biological activity [31]. 

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. 

Turnipseed et al. described a method for the multi-class residue determination of P-Iactams, sulfonamides, tetracyclines, fluoroquinolones, and macroiides in milk and other dairy products. The sample preparation combines extraction with acetonitrile, clean-up with Oasis HLB cartridges, and ultrafiltration using molecular weight cut-off filters to improve the overall performance of the analysis. Acceptable recoveries were obtained for sulfanomides, macroiides, and quinolones (>70%) however, recoveries were rather low for tetracyclines (50-60%) and P-lactams (<50%). Despite the extensive clean-up procedure, significant matrix ion suppression was observed for many compounds, making it necessary to include matrix-matched calibration standards for quantification purposes. 

Dairy products P-Lactams (12) Sulfonamides (4) Tetracyclines (3) Aminoglycosides (4) Macrolides (5) Lincosamides (I) Novobiocin Spectinomycin Chloramphenicol Raw, commingled, and pasteurized milk None 10... 

If the antibiotic is tetracycline, milk and dairy products can reduce its effectiveness. For that reason, it is best to take tetracycline an hour before or two hours after milk or dairy products. 

The calcium in food can complex with tetracycline to reduce its absorption. This is particularly notable with dairy products, which can reduce the absorption of the tetracyclines by up to 80%, thereby reducing or even abolishing their therapeutic effects. Doxyeyeline and minocycline are less affected by daily products (25 to 30% reduction). Orange juice and coffee do not interact with tetracycline. 

The tetracyclines have a strong affinity for the calcium ions that are found in abundance in dairy products and some foodstuffs. The fefracycline/cal-cium chelafes formed are much less readily absorbed from fhe gasfroinfes-final fracf and as a result the serum tetracycline levels achieved are much lower. Some tetracyclines have a lesser tendency to form chelates, which explains why their serum levels are reduced to a smaller extent. ... 

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. 

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