Rifampicin Antacids

NA /D, abd pain, bleeding, fevCT, T QT Interactions t Effects W7 atazanavir, clarithromycin, CT5rthromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfi-navir, ritonavir, saquinavir, telithromycin X effects W7 antacids, carbamazqjine, dexamethasone, phenobarbital, phenytoin, rifampicin, St. John s wort EMS Drug contains lactose, may cause D/abd discomfort in pts w/ lactose intolerance OD Sxs unknown symptomatic and supportive... 

Drug Interactions Gemfibrozil Niacin Erythromycin Cholestyramine Digoxin Cimetidine/ranitidine/ omeprazole Rifampicin Warfarin Itraconazole Gemfibrozil Niacin Erythromycin Propranolol Digoxin Warfarin Antacids Colestipol Digoxin Erythromycin Oral contraceptives Fibrates Niacin Azole antifungals... 

Interactions. Drugs that lower gastric acidity, e.g. antacids, histamine H2 receptor antagonists, impair the absorption of ketoconazole from the gastrointestinal tract. Like all imidazoles, ketoconazole binds strongly to several cytochrome P450 isoenzymes and thus inhibits the metabolism (and increases effects of) oral anticoagulants, phenytoin and cyclosporin, and increases the risk of cardiac arrhythmias with terfenadine. A disulfiram-like reaction occurs with alcohol. Concurrent use of rifampicin, by enzyme induction of CYP 3A, markedly reduces the plasma concentration of ketoconazole. 

Antacids, particularly aluminium hydroxide gel, magnesium trisilicate, and sodium bicarbonate, reduce the systemic availability of rifampicin (97). 

Khalil SAH, El-Khordagui LK, El-Gholmy ZA. Effect of antacids on oral absorption of rifampicin. Int J Pharm 1984 20 99. 

A reduction in efficacy due to an interaction can sometimes be just as harmful as an increase patients taking warfarin who are given rifampicin need more warfarin to maintain adequate and protective anticoagulation (see Coumarins + Antibacterials Rifamycins , p.375), while patients taking tetracyclines , (p.347) or quinolones , (p.332) need to avoid antacids and milky foods (or separate their ingestion) because the effects of these antibacterials can be reduced or even abolished if admixture occurs in the gut. 

The absorption of rifampicin can be reduced up to about one-third by antacids, but the clinical importance of this is uncertain. 

When 5 healthy subjects took a single 600-mg dose of rifampicin with various antacids the absorption of rifampicin was reduced. The antacids caused a fall in the urinary excretion of rifampicin as follows 15 or 30 mL of aluminium hydroxide gel 29 to 31% 2 or 4 g of magnesium trisilicate 31 to 36% and 2 g of sodium bicarbonate 21%. ... 

Direct information seems to be limited to these reports. The effeets of 20 to 35% reductions in rifampicin absorption do not appear to have been assessed, but if antacids are given it would be prudent to be alert for any evidence that treatment is less effective than expected. The US manufacturers of rifampicin advise giving rifampicin 1 hour before antacids. ... 

Gupta PR, Mehta YR, Gupta ML, Sharma TN, Jain D, Gupta RB, Rifampicin-aluminium antacid interaction, J Assoc Physicians India (1988) 36, 363-4,... 

Deferasirox did not alter the pharmacokinetics of digoxin. Food increases the bioavailability of deferasirox, and it should be taken on an empty stomach. The use of deferasirox with aluminium antacids is not recommended. Rifampicin, phenobarbital and pheny-toin are predicted to increase the metabolism of deferasirox, and, until more is known, concurrent use should be monitored. Based on in vitro data, deferasirox might inhibit the metabolism of CYP2C8 substrates like paclitaxel and repaglinide. Hydroxycar-bamide does not alter deferasirox metabolism. 

The adverse effect profile of roflmnilast has been described previously. However, new data became available recently. A systematic review smnmarised the available data on adverse effects and drug reactions of roflmnilast. This systematic review was based on six clinical trials with a total population of 9102 COPD patients, with the study duration ranging between 24 and 52 weeks [89 ]. Roflmnilast is metabolised by CYP 3A4, CYP 2C19 and CYP 1A2. Inhibitors of these enzymes such as erythromycin or ketoconazole were shown to increase the activity and half-life of roflumilast. In contrast, drugs that induced these enzymes, like rifampicin, had the opposite effect, reducing the activity and half-life of roflumilast. Roflumilast did not significantly interact with montelukast, budesonide, or antacids. 

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