Drug Interactions between fluconazole and rabeprazole

Published observational studies suggest that proton pump inhibitor (PPI) use may be associated with an increased risk of Clostridium difficile-associated diarrhea (CDAD), especially in hospitalized patients. This diagnosis should be considered for diarrhea that does not improve. It is recommended that patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated. Close monitoring is recommended in patients with diarrhea and in those taking antibacterial agents as CDAD has been reported with the use of nearly all these agents. Treatment with antibacterial agents alters the normal flora of the colon, leading to overgrowth of C. difficile. C. difficile produces toxins A and B, which contribute to the development of CDAD. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

The use of fluconazole has been rarely associated with hepatotoxicity. Reversible idiosyncratic hepatitis, cholestasis and fatal fulminant hepatic failure have been reported, the latter occurring primarily in patients with serious underlying medical conditions and taking multiple concomitant medications. Liver function tests should be performed periodically in patients with preexisting hepatic abnormalities, particularly during prolonged therapy. Treatment should be withdrawn if persistent elevations or worsening of liver enzyme levels occur.

Published observational studies suggest that proton pump inhibitor (PPI) use may be associated with an increased risk of Clostridium difficile-associated diarrhea (CDAD), especially in hospitalized patients. This diagnosis should be considered for diarrhea that does not improve. It is recommended that patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated. Close monitoring is recommended in patients with diarrhea and in those taking antibacterial agents as CDAD has been reported with the use of nearly all these agents. Treatment with antibacterial agents alters the normal flora of the colon, leading to overgrowth of C. difficile. C. difficile produces toxins A and B, which contribute to the development of CDAD. Appropriate fluid and electrolyte management, protein supplementation, antibiotic treatment of C. difficile, and surgical evaluation should be instituted as clinically indicated.

Some azole antifungals have been associated with prolongation of the QT interval on the ECG. Rare cases of QT prolongation and torsade de pointes have been reported during postmarketing experience; such reports usually involved seriously ill patients with multiple confounding risk factors, such as structural heart disease, electrolyte abnormalities, and concomitant medications. These drugs should be administered with caution to patients with potentially proarrhythmic conditions, such as congenital/acquired QT prolongation, cardiomyopathy (especially when heart failure is present), sinus bradycardia, and existing symptomatic arrhythmias. Concomitant use with other medications that have potential to increase the risk of cardiotoxicity should be avoided.

Fluconazole is substantially removed by hemodialysis. Plasma levels of fluconazole has been shown to reduce by 50% following 3 hours of dialysis. Fluconazole should be administered after hemodialysis.

Rabeprazole is primarily metabolized by the liver. Although the drug is generally well-tolerated, therapy with rabeprazole should be administered cautiously in patients with severe liver disease because of the lack of clinical data concerning its use in such patients. Dosage adjustments are not necessary in patients with mild to moderate hepatic impairment.

Symptomatic and asymptomatic hypomagnesemia has been reported rarely in patients treated with PPIs for at least 3 months, in most cases after a year of therapy. Serious adverse events can include tetany, seizures, and arrhythmias. Caution should be used in patients prone to magnesium imbalances such as patients taking other medications that can cause hypomagnesemia (e.g., diuretics). Regular monitoring is recommended.

Various published observational studies have reported that PPI therapy may be associated with an increased risk for osteoporosis related fractures of the hip, wrist or spine. The risk was increased in patients who received high doses (multiple daily doses), and long term treatment (a year or longer). Patients should use the lowest dose and shortest duration of PPI therapy appropriate to the condition being treated. Caution should be used in patients at risk for osteoporosis related fractures and should be managed according to established treatment guidelines.

Fluconazole is primarily eliminated by the kidney. Patients with renal impairment may be at greater risk for adverse effects from fluconazole due to decreased drug clearance. Dosage adjustments are recommended for patients with moderate to severe renal impairment (CrCl <= 50 mL/min) receiving multiple doses of the drug.