Tetracycline Sodium bicarbonate

SODIUM BICARBONATE TETRACYCLINE 1 tetracycline levels and possible therapeutic failure It is suggested that when sodium bicarbonate alkalinizes the urine, the renal excretion of tetracycline t The interaction can be minimised by administering the doses 3-4 hours apart... 

Oral administration of bicarbonate may decrease the absorption of ketoconazole. Increased blood levels of quinidine, flecainide, or sympatiiomimetics may occur when these agents are administered with bicarbonate There is an increased risk of crystalluria when bicarbonate is administered with the fluoroquinolones. Fbssible decreased effects of lithium, methotrexate, chlorpropamide, salicylates, and tetracyclines may occur when these drag s are administered with sodium bicarbonate. Sodium bicarbonate is not administered within 2 hours of enteric-coated drugs the protective enteric coating may disintegrate before the drug reaches the intestine. 

The tetracyclines should be taken orally 1 h before or 2 h after meals. Absorption of these agents is impaired by the presence of milk and milk products and by the concomitant administration of aluminum hydroxide gels, sodium bicarbonate, calcium and magnesium salts, or iron preparations because of the chelation of divalent and trivalent cations by these agents. 

Tetracyclines, as broad-spectrum antibiotics, are the drugs of choice in treating Mycoplasma pneumoniae infections. Most tetracyclines are absorbed to various degrees (30 to 100%) from the gastrointestinal tract, primarily from the stomach and upper small intestine. The absorption of tetracyclines is hindered by milk and milk products, by numerous antacids such as aluminum hydroxide, sodium bicarbonate, and calcium carbonate, and by iron preparations such as ferrous sulfate. Therefore, these and similar substances should not be administered orally together with tetracycline (Figure 3.4). 

Because acid-pepsin disease rarely occurs in the absence of gastric acid and pepsin, antacids are highly effective in its overall management. Antacids consist of a mixture of magnesium, aluminum, and calcium compounds. Their efficacy is based on their inherent ability to react with and neutralize gastric acid. Sodium bicarbonate, which may leave the stomach rapidly, can cause alkalosis and sodium retention. Calcium salts may produce hypercalcemia, which can be detrimental in patients with impaired renal function. Aluminum salts may decrease the absorption of tetracyclines and anticholinergic drugs. 

Tetracycline Sodium bicarbonate, cimetidine, Alkaline pH inhibits dissolution,... 

The administration of tetracycline with food can ameliorate its irritative effects, bnt food can adversely affect the drug s absorption. In contrast, the absorption of doxycycline is only slightly affected by the presence of food, including dairy prodncts. Becanse all tetracyclines can form complexes with divalent cations, the absorption of any tetracycline is markedly decreased when administered with iron-containing tonics or antacids containing calcium, magnesium, or aluminum. Sodium bicarbonate also adversely affects tetracycline absorption. 

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. 

The serum levels and therefore the therapeutic effectiveness of the tetracyclines can be markedly reduced or even abolished by antacids containing aluminium, bismuth, calcium or magnesium. Other antacids, such as sodium bicarbonate, may also reduce the bioavailability of some tetracyclines. Even intravenous doxycy-cline levels can be reduced by antacids. 

Sodium bicarbonate 2 g reduced the absorption of a 250-mg capsule of tetracycline by 50% in 8 subjects. If however tetracycline was dissolved before administration, the absorption was unaffected by the sodium bicarbonate. Another study stated that sodium bicarbonate 2 g had an insignificant effect on tetracycline absorption. ... 

Barr WH, Adir J, Garrettson L. Decrease of tetracycline absorption in man by sodium bicarbonate. Clin Pharmacol Ther ( 97 ) 12, 779-84. 

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