Ketoconazole alters cyclosporine pharmacokinetic profile and may predispose to acute rejection

No Increased Risk of Ketoconazole Toxicity in Drug-Drug Interaction Studies

In July 2013 the U.S. Food and Drug Administration (FDA) released a safety announcement regarding the use of ketoconazole and its adverse drug reactions. The FDA report advised against the use ketoconazole tablets as a first-line treatment for any fungal infections because of the risk of potentially serious drug-drug interactions and liver and adrenal gland complications. The European Medicines Agency (EMA) also proposed to limit the use of oral ketoconazole in fungal infections because of the same risk of harmful effects and interactions. In addition, the FDA also advised against the use of oral ketoconazole in drug interaction studies, in which it has been extensively used as an index inhibitor of drug metabolism. The aim of this investigation was to evaluate the risks of ketoconazole-induced hepatotoxicity described by the FDA and EMA in published drug interaction studies with ketoconazole and compare these data with the toxicity reported for ketoconazole when used as antifungal treatment. In the drug interaction studies (2355 participants; healthy volunteers and patients; median treatment duration, 6 days), only 40 participants were reported to have increased liver transaminase activity (1.7%), and no deaths were reported or associated with ketoconazole. In studies investigating ketoconazole treatment, patients were treated for 276 days (median), and 5.6% of patients had elevated liver enzyme activity. Because of the short treatment period in drug interaction studies the risk of drug-induced hepatic injury is considered very low. As such, we recommend that ketoconazole remain a safe CYP3A index inhibitor for use in drug interaction studies with healthy volunteers.

Combining cytochrome P-450 3A4 modulators and cyclosporine or everolimus in transplantation is successful

AIM: To describe the long term follow-up of kidney allograft recipients receiving ketoconazole with calcineurin inhibitors (CNI) alone or combined with everolimus.

METHODS: This is an open-label, prospective observational clinical trial in low immunologic risk patients who, after signing an Institutional Review Board approved consent form, were included in one of two groups. The first one (n = 59) received everolimus (target blood level, 3-8 ng/mL) and the other (n = 114) azathioprine 2 mg/kg per day or mycophenolate mofetyl (MMF) 2 g/d. Both groups also received tapering steroids, the cytochrome P-450 3A4 (CYP3A4) modulator, ketoconazole 50-100 mg/d, and cyclosporine with C0 targets in the everolimus group of 200-250 ng/mL in 1 mo, 100-125 ng/mL in 2 mo, and 50-65 ng/mL thereafter, and in the azathioprine or MMF group of 250-300 ng/mL in 1 mo, 200-250 ng/mL in 2 mo, 180-200 ng/mL until 3-6 mo, and 100-125 ng/mL thereafter. Clinical visits were performed monthly the first year and quarterly thereafter by treating physicians and all data was extracted by the investigators.

RESULTS: The clinical characteristics of these two cohorts were similar. During the follow up (66 + 31 mo), both groups showed comparable clinical courses, but the biopsy proven acute rejection rate during the full follow-up period seemed to be lower in the everolimus group (20% vs 36%; P = 0.04). The everolimus group did not show a higher surgical complication rate than the other group. By the end of the follow-up period, the everolimus group tended to show a higher glomerular filtration rate. Nevertheless, we found no evidence of a consistent negative slope of the temporal allograft function estimated by the modification of the diet in renal disease formula in any of both groups. At 6 years of follow-up, the uncensored and death-censored graft survivals were 91% and 93%, and 91% and 83% in the everolimus plus cyclosporine, and cyclosporine alone groups, respectively. The addition of ketoconazole saved 80% of cyclosporine and 56% of everolimus doses.

CONCLUSION: Combining CYP3A4 modulators with CNI or mammalian target of rapamycin inhibitor, in low immunological risk kidney transplant recipients is feasible, effective, safe and affordable even in the long term.

Factors Influencing the Magnitude and Clinical Significance of Drug Interactions Between Azole Antifungals and Select Immunosuppressants

The magnitude of drug interactions between azole antifungals and immunosuppressants is drug and patient specific and depends on the potency of the azole inhibitor involved, the resulting plasma concentrations of each drug, the drug formulation, and interpatient variability. Many factors contribute to variability in the magnitude and clinical significance of drug interactions between an immunosuppressant such as cyclosporine, tacrolimus, or sirolimus and an antifungal agent such as ketoconazole, fluconazole, itraconazole, voriconazole, or posaconazole. By bringing similarities and differences among these agents and their potential interactions to clinicians' attention, they can appreciate and apply these findings in a individualized patient approach rather than follow only the one-size-fits-all dosing recommendations suggested in many tertiary references. Differences in metabolism and in the inhibitory potency of cytochrome P450 3A4 and P-glycoprotein influence the onset, magnitude, and resolution of drug interactions and their potential effect on clinical outcomes. Important issues are the route of administration and the decision to preemptively adjust dosages versus intensive monitoring with subsequent dosage adjustments. We provide recommendations for the concomitant use of these agents, including suggestions regarding contraindicated combinations, those best avoided, and those requiring close monitoring of drug dosages and plasma concentrations.