Drug Interactions between bedaquiline and famotidine / ibuprofen

GENERALLY AVOID: Coadministration of bedaquiline with other agents known to induce hepatotoxicity may potentiate the risk of liver injury. In clinical trials, hepatic adverse drug reactions developed in more bedaquiline-treated patients than in those who received other drugs used to treat tuberculosis. In patients receiving bedaquiline or placebo in combination with other drugs used to treat multidrug-resistant tuberculosis, reversible aminotransferase elevations of at least 3 times the upper limit of normal (ULN) developed more frequently in the bedaquiline treatment group [10.8%] than in the placebo group [5.7%].

MANAGEMENT: The use of bedaquiline with other potentially hepatotoxic agents should be avoided whenever possible (e.g., acetaminophen; alcohol; androgens and anabolic steroids; other antituberculous agents; azole antifungal agents; ACE inhibitors; disulfiram; endothelin receptor antagonists; ketolide and macrolide antibiotics; interferons; kinase inhibitors; minocycline; nonsteroidal anti-inflammatory agents; nucleoside reverse transcriptase inhibitors; proteasome inhibitors; retinoids; sulfonamides; tamoxifen; thiazolidinediones; tolvaptan; vincristine; zileuton; anticonvulsants such as carbamazepine, hydantoins, felbamate, and valproic acid; lipid-lowering medications such as fenofibrate, lomitapide, mipomersen, niacin, and statins; herbals and nutritional supplements such as black cohosh, chaparral, comfrey, DHEA, kava, pennyroyal oil, and red yeast rice), especially in patients with diminished hepatic reserve. Patients treated with bedaquiline should have serum ALT, AST, alkaline phosphatase, and bilirubin monitored at baseline and monthly during treatment, or as often as needed. An increase of serum aminotransferases to greater than 3 times ULN should be followed by repeat testing within 48 hours. Patients should be advised to seek medical attention if they experience potential signs and symptoms of hepatotoxicity such as fever, rash, itching, anorexia, nausea, vomiting, fatigue, malaise, right upper quadrant pain, dark urine, pale stools, and jaundice. Discontinue bedaquiline if aminotransferase elevations are accompanied by total bilirubin elevation greater than 2 times ULN, aminotransferase elevations are greater than 8 times ULN, or aminotransferase elevations persist beyond 2 weeks.

MONITOR: Famotidine may cause QTc prolongation. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. According to the manufacturer, prolongation of the QT interval has been reported very rarely in patients with impaired renal function whose dose/dosing interval of famotidine may not have been adjusted appropriately. In general, the risk of an individual agent or a combination of these agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Caution and clinical monitoring are recommended if famotidine is used in combination with other drugs that can prolong the QT interval. Patients should be advised to seek prompt medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitation, irregular heart rhythm, shortness of breath, or syncope.

H2 antagonists may alter the pharmacokinetic disposition of some nonsteroidal anti-inflammatory drugs (NSAIDs), resulting in increased or decreased plasma concentrations. Data have been varied, even for the same NSAID. The mechanism may involve inhibition of metabolism, changes in gastric pH resulting in altered absorption, and/or reduced urinary elimination of the affected NSAIDs. Statistically significant changes have been small and of limited clinical significance when interactions have been observed.