Hydroxides, antacid

Calcium carbonate or magnesium hydroxide antacids may decrease the effectiveness of the digestive enzymes. When administered concurrently with an iron preparation, the digestive enzymes decrease the absorption of oral iron preparations. 

Carmichael KA, Fallon MD, Dalinka M, et al. 1984. Osteomalacia and osteitis fibrosa in a man ingesting aluminum hydroxide antacid. Am J Med 76 1137-1143. 

Chronic aluminium hydroxide antacid intake (600 cm weekly) can cause osteomalacia... 

Cederberg C, Andersson T, Skanberg 11989 Omeprazole pharmacokinetics and metabolism in man. Scandinavian Journal of Gastroenterology Supplement 166 33-42 Clark C K, Merritt A M, Burrow J A et al 1996 Effect of an aluminum-magnesium hydroxide antacid and BSS on gastric pH in horses. Journal of the American Veterinary Medical Association 208 1687-1691 Clarke L L, Argenzio R A, Roberts M C 1990 Effect of meal feeding on plasma volume and urinary electrolyte clearance in ponies. American Journal of Veterinary Research 51 571-576... 

Clinically important, potentially hazardous interactions with aluminum hydroxide, antacids, ascorbic acid, bone marrow suppressants, chloroquine, cytotoxic agents, food, gold, hydroxychloroquine, iron, magnesium, primaquine, probenecid... 

Clinically important, potentially hazardous interactions with aluminium hydroxide, antacids, charcoal, cholestyramine, colestimide, colestipol, cyclosporine, cytochrome P4503A substrates, dapsone, estrogenic hormones, nitrendipine, oral contraceptives... 

Although the lipid solubility of sotalol is relatively low compared with other jS-blocking adrenoceptor drugs (28), oral bioavailability is deemed to be 1(X)%. Sotalol is absorbed somewhat slower than most other j8-blockers, with peak concentrations occuring within 2-3 hours (29). Although food may impair the absorption of sotalol (28), administration of either calcium carbonate or aluminum hydroxide antacids has little effect on absorption (30). After administration of a single 160 mg oral dose of sotalol, both enantiomers reached maximal plasma concentrations in approximately 3 hours (31) and, hence, did not exhibit stereoselective absorption. 

An aluminium/magnesium hydroxide antacid reduced the bioavailability of captopril by 40%, but this did not seem to be clinically important The bioavailability of fosinopril was reduced by about one-third by Mylanta. An antacid did not affect ramipril pharmacokinetics. 

In 24 healthy subjects an aluminium/magnesium hydroxide antacid (Maalox) had no effect on the rate or extent of absorption of a single 25-mg dose of dexketoprofen, although the maximum level was slightly (13%) lower. ... 

The pharmacokinetics of lomoxicam, meloxicam, piroxicam and tenoxicam were not affected by aluminium/magnesium hydroxide antacids. Lomoxicam pharmacokinetics were also not altered by tripotassium dicitratobismuthate or aluminium hydroxide with calcium carbonate. 

The absorption of flecainide is not significantly altered if it is taken with food or an aluminium hydroxide antacid in adults, but it may possibly be reduced by milk in infants. 

Large rises in urinary pH due to the concurrent use of some antacids, diuretics or alkaline salts can cause quinidine retention, which could lead to quinidine toxicity, but there seems to be only one case on record of an adverse interaction (with an alumini-um/magnesium hydroxide antacid). Aluminium hydroxide alone appears not to interact. 

No clinically significant interactions appear to occur between an aluminium/magnesium hydroxide antacid and cefaclor AF, ce-falexin, cefetamet pivoxil, cefixime or cefprozil between Alka-Seltzer and cefixime or between ceftibuten and Mylanta. In contrast, antacids reduce the bioavailability of cefpodoxime proxetil. 

A study with cefaclor AF (a formulation with a slow rate of release) found that an aluminium/magnesium hydroxide antacid (Maalox) given one hour after the cefaclor AF to fed subjects reduced the AUC by 18%. This reduction is small and unlikely to be clinically important. 

An aluminium/magnesium hydroxide antacid (Maalox) given as 8 doses of 10 niL on day one and 2 doses on day 2, had only small and therapeu-tieally unimportant effeets on the pharmacokinetics of cefalexin 1 g. ... 

An aluminium/magnesium hydroxide antacid (Maalox) and AlkaSelt-zer (aspirin, calcium phosphate, citric acid and sodium bicarbonate) do not significantly affect the absorption of cefixime, ... 

A study in 10 healthy subjects found that 10 mL of an aluminium/magnesium hydroxide antacid (Maalox) reduced the bioavailability of cefpodoxime proxetil by about 40%. This was considered to be due to reduced dissolution at increased gastric pH values. These results confirm the findings of a previous study with sodium bicarbonate and aluminium hydroxide. It has been recommended that cefpodoxime is given at least 2 hours after antacids. ... 

A study in 13 patients with tuberculosis, given a single 50-mg/kg dose of ethambutol, found that when they were also given three 1.5-g doses of aluminium hydroxide gel (at the same time and 15 and 30 minutes later) their peak serum ethamhutol levels were delayed and reduced. The average uri nary excretion of ethamhutol over a 10-hour period was reduced hy about 15%, but there were marked variations between individual patients. Some showed no interaction, and others showed increased absorption. No interaction was seen in 6 healthy subjects similarly treated. A further study in 14 healthy subjects found that 30 mL of an aluminium/magnesi-um hydroxide antacid decreased the AUC and maximum serum levels of a 25-mg/kg dose of ethambutol by 10% and 29%, respectively. ... 

Aluminium/magnesium hydroxide antacids are reported not to affect the pharmacokinetics of clarithromycin, roxithromycin, or telithro-mycin. 

Aluminium/magnesium hydroxide antacids may reduce the peak levels of azithromycin. Mylanta can prolong the absorption of erythromycin, but this is unlikely to be clinically important Aluminium/magnesium hydroxide antacids do not appear to significantly alter the pharmacokinetics of clarithromycin, roxithromycin or telithromycin. 

The absorption of metronidazole is unaffected by kaolin-pectin, but it is slightly reduced by an aluminium hydroxide antacid and colestyramine, although not to a clinically relevant extent. 

Lazzaroni M, Imbimbo BP, Bargiggia S, Sangaletti O, Dal Bo L, Broccali G, Bianchi Porro G. Effects of magnesium-aluminum hydroxide antacid on absorption of rufloxacin. Antimicrob Agents Chemother 190 S) 37, 2212-16. 

An aluminium/magnesium hydroxide antacid Maalox TO) reduced the bioavailability of gabapentin 400 mg by about 20% when given either at the same time or 2 hours after gabapentin. When the antacid was given 2 hours before the gabapentin, the bioavailability was reduced by about 10%. These small changes are unlikely to be of clinical importance. How-... 

Elsewhere, 2 epileptie patients are reported to have had inadequate seizure eontrol, which coincided with the ingestion of aluminium/magnesi-um hydroxide antacids for dyspepsia. The AUC of a single dose of phenytoin was reduced by about 25% in 8 healthy subjects given either aluminium/magnesium hydroxide or caicium carbonate. ... 

The manufacturer notes that when a single 120-mg dose of fexofenadine was given within 15 minutes of an aluminium/magnesium hydroxide antacid (Maalox), the fexofenadine AUC was decreased by 41% and the maximum level was decreased by 43%. Although the effect of these reductions on possible efficacy has not been assessed, the manufacturer recommends that it is advisable to leave 2 hours between the administration of fexofenadine and antacids containing aluminium and magnesium hydroxide. ... 

The absorption of capecitabine was not affected by an alumini-um/magnesium hydroxide antacid. 

A study in 12 patients found that 20 mL of an aluminium/magnesium hydroxide antacid (Maalox) caused a small increase in the plasma levels of a single 1250-mg/m oral dose of capecitabine and one metabolite (5 -DFCR) but it had no effect on the other 3 major metabolites (5 DFUR, 5-FU and FBAL). There would therefore seem to be no reason for taking special precautions if capecitabine and an antacid of this type are used concurrently. 

Antacids containing aluminium/magnesium hydroxide or magnesium trisilicate can reduce the serum levels of chlorpromazine which would be expected to reduce the therapeutic response. Sucralfate and an aluminium/magnesium hydroxide antacid can reduce the absorption of sulpiride. In vitro studies suggest that this interaction may possibly also occur with other antacids and phe-nothiazines. There seem to be no clinical studies or reports confirming the anecdotal evidence of a possible reduction in the effects of haloperidol by antacids. 

Activated charcoal causes a fall in olanzapine levels and venlafax-ine moderately raise olanzapine levels. Additive dopaminergic effects have been seen in one patient taking olanzapine and haloperidoL Olanzapine appears not to interact to a clinically relevant extent with aluminium/magnesium hydroxide antacids, ci-metidine or diazepam. However, excessive sedation and hypotension may occur with parenteral benzodiazepines and intramuscular olanzapine. 

The manufacturers warn of the possible risks of giving ziprasidone with drugs that prolong the QT interval, and of the possible antagonism that may occur with ievodopa and other dopamine agonists. Ziprasidone appears not to interact to a clinically relevant extent with an aiuminium/magnesium hydroxide antacid, benzatropine, cimetidine, iorazepam, propranolol or tobacco smoking. 

Valaciclovir does not interact with an aluminium/magnesium hydroxide antacid. 

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