Isoniazid Antacids

Antacids Isoniazid, phenytoin, propranolol and Decreased rate of... 

The following drugp have a decreased pharmacologic effect when administered with an antacid corticosteroids, digoxin, chlorpromazine, oral iron products, isoniazid, phenothiazines, ranitidine, phenytoin, valproic acid, and the tetracyclines. 

Antacids also have clinically significant drug interactions with tetracycline, ferrous sulfate, isoniazid, quinidine, sul-fonylureas, and quinolone antibiotics. Antacid-drug interactions are influenced by antacid composition, dose, dosage schedule, and formulation. 

Drugs that may affect benzodiazepines include alcohol, antacids, barbiturates, cimetidine, disulfiram, fluoxetine, isoniazid, ketoconazole, metoprolol, oral contraceptives, narcotics, probenecid, propoxyphene, propranolol, ranitidine, rifampin, scopolamine, theophylline, and valproic acid. 

Drugs that may affect ketoconazole include antacids, didanosine, histamine H2 antagonists, isoniazid, sucralfate, proton pump inhibitors, and rifampin. Drugs that may be affected by ketoconazole include oral anticoagulants, corticosteroids, cyclosporine, protease inhibitors, tricyclic antidepressants, carbamazepine. 

Drugs that may interact with zalcitabine include antacids, chloramphenicol, cisplatin, dapsone, didanosine, disulfiram, ethionamide, glutethimide, gold, hydralazine, iodoquinol, isoniazid, metronidazole, nitrofurantoin, phenytoin, ribavirin, vincristine, cimetidine, metoclopramide, amphotericin, aminoglycosides, foscarnet, antiretroviral nucleoside analogs, pentamidine, and probenecid. 

Isoniazid is water soluble and is well absorbed when administered either orally or parenterally. Oral absorption is decreased by concurrent administration of aluminum-containing antacids. 

Antacids Tetracyciine, isoniazid, atenoioi, chiorpromazine peniciiiamine, digoxin, ranitidine Decreased absorption... 

Zalcitabine NRTI1 0.75 mg tid3 Administer 1 h before or 2 h after an antacid Peripheral neuropathy oral ulcerations, pancreatitis, headache, nausea, rash, arthralgias Avoid concurrent cimetidine avoid concurrent neuropathic drugs (eg, ddl, zalcitabine, isoniazid). Do not administer with lamivudine... 

Didanosine3 NRTI 150-200 mg bid, depending on weight. Enteric-coated 250-400 mg qd, depending on weight 30 minutes before or 2 hours after meals Peripheral neuropathy, pancreatitis, diarrhea, hyperuricemia Contains antacid avoid alcohol avoid concurrent neuropathic drugs (eg, didanosine, zalcitabine, isoniazid)... 

ISONIAZID ANTACIDS 1 levels of these antibiotics i absorption Separate isoniazid and antacids by 2-3 hours... 

ANTACIDS ANTIBIOTICS - AZITHROMYCIN, CEFPODOXIME, CEFUROXIME, ISONIAZID, NITROFURANTOIN, QUINOLONES, RIFAMYCINS, TETRACYCLINES 1 levels of these antibiotics 1 absorption Take azithromycin at least 1 hour before or 2 hours after an antacid. Take these cephalosporins at least 2 hours after an antacid. Separate quinolones and antacids by 2-6 hours. Separate nitrofurantoin, rifamycins or tetracyclines and antacids by 2-3 hours... 

Peloquin CA, Namdar S, Dodge AA, Nix DE. Pharmacokinetics of isoniazid under fasting conditions, with food, and with antacids. Int J Tuberc Lung Dis 1999 3 703-10. 

Absorption of isoniazid can be inhibited by aluminium-containing antacids (51). 

Clinically important, potentially hazardous interactions with amiodarone, amprenavir, anisindione, antacids, anticoagulants, aprepitant, atazanavir, atovaquone, beclomethasone, buprenorphine, corticosteroids, cortisone, cyclosporine, cyproterone, dabigatran, dapsone, darunavir, delavirdine, dexamethasone, dicumarol, digoxin, eszopiclone, flunisolide, fosamprenavir, gadoxetate, gestrinone, halothane, imatinib, isoniazid, itraconazole, ketoconazole, lapatinib, lorcainide, methylprednisolone, midazolam, nelfinavir, nifedipine, oral contraceptives, phenylbutazone, prednisone, protease inhibitors, pyrazinamide, ramelteon, ritonavir, saquinavir, solifenacin, sunitinib, tacrolimus, telithromycin, temsirolimus, tipranavir, tolvaptan, trabectedin, triamcinolone, triazolam, voriconazole, warfarin, zaleplon... 

Therefore, plasma concentrations for drugs metabolized by these isoforms will be affected (see Chapter 10). Thus, the addition of phenytoin to an AED regimen can reduce their plasma levels by inducing their CYP3A4 metabolism for carbamazepine, felbamate, lamotrigine, oxcarbazepine, tiagabine, valproate, and zonisamide. Other drugs for which metabolism is induced by phenytoin include methadone, theophylline, warfarin, and oral contraceptives. On the other hand, plasma phenytoin levels are increased by carbamazepine, felbamate, cimetidine, warfarin, chloramphenicol, isoniazid, and disulfiram. Plasma phenytoin levels are decreased by rifampin, antacids, and valproate (free phenytoin levels remain the same). 

Didanosine chewable tablets contain antacids (aluminium/magnesium hydroxide) in the formulation, but it has been shown that they do not affect the bioavailability of isoniazid. ... 

HurwitzA, SchlozmanDL. Effects of antacids on gastrointestinal absorption of isoniazid in rat and man. AmRevRespirDis 91A) 109, 41-7,... 

Gallicano K, Sahai J, Zaror-Behrens G, Pakuts A. Effect of antacids in didanosine tablet on bioavailability of isoniazid. Antimicrob Agents Chemother (1994) 38, 894-7. 

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