Drug Interactions between emtricitabine / lopinavir / ritonavir / tenofovir disoproxil and voclosporin

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of voclosporin, which is primarily metabolized by the isoenzyme. Elevated plasma concentrations of voclosporin may increase the risk for adverse effects such as acute and/or chronic nephrotoxicity, infection, hypertension, neurotoxicity, and QT prolongation. The risk of QT prolongation in particular may be increased with concomitant use of potent CYP450 3A4 inhibitors that are also known to prolong the QT interval (e.g., ceritinib, mibefradil, saquinavir, telithromycin). Drug interaction studies have shown that coadministration with the potent CYP450 3A4 inhibitor ketoconazole (400 mg daily for 9 days) increased the peak plasma concentration (Cmax) and systemic exposure (AUC) of voclosporin by approximately 6.45- and 18.55-fold, respectively.

MANAGEMENT: The use of voclosporin in combination with potent CYP450 3A4 inhibitors is considered contraindicated.

GENERALLY AVOID: Coadministration of tenofovir with other nephrotoxic agents may increase the risk of renal impairment due to additive effects on the kidney. Additionally, renal impairment secondary to the use of these agents may reduce the clearance of tenofovir, which is primarily eliminated by a combination of glomerular filtration and active tubular secretion. The use of tenofovir has been associated with dose-related nephrotoxicity including acute renal failure and Fanconi syndrome characterized by renal tubular injury with severe hypophosphatemia, possibly as a result of mitochondrial toxicity. Cases of acute renal failure after initiation of high-dose or multiple nonsteroidal anti-inflammatory agents have been reported in HIV-infected patients with risk factors for renal dysfunction who appeared stable on tenofovir therapy. Some patients required hospitalization and renal replacement therapy. Available clinical data seem to suggest a lower risk of nephrotoxicity with tenofovir alafenamide fumarate (TAF) than with tenofovir disoproxil fumarate (TDF), presumably due to lower tenofovir systemic exposure following administration of TAF relative to TDF. Whereas TDF is metabolized in plasma to tenofovir and phosphorylated intracellularly to the active moiety tenofovir diphosphate, TAF is largely metabolized and phosphorylated intracellularly, resulting in substantially higher intracellular concentrations of tenofovir diphosphate and lower plasma levels of tenofovir at the therapeutic dose of 25 mg compared to TDF 300 mg. It has been further reported that tenofovir is actively transported into the proximal renal tubular cell by organic anion transporters (OAT) 1 and 3, but that TAF is not a substrate for these transporters and thus less likely to cause tubular injury. There have been no cases of Fanconi syndrome or proximal renal tubulopathy in clinical trials of various TAF-containing products according to the manufacturers.

MANAGEMENT: The use of tenofovir in patients who have recently received or are receiving treatment with other potentially nephrotoxic agents (e.g., aminoglycosides; polypeptide, glycopeptide, and polymyxin antibiotics; amphotericin B; aminosalicylates; antiviral agents such as acyclovir, adefovir, cidofovir, foscarnet, and ganciclovir; antineoplastics such as aldesleukin, cisplatin, clofarabine, ifosfamide, streptozocin, and high intravenous dosages of methotrexate; chelating agents such as deferasirox, deferoxamine, edetate disodium, and edetate calcium disodium; immunosuppressants such as cyclosporine, everolimus, sirolimus, and tacrolimus; intravenous bisphosphonates; intravenous pentamidine; high dosages and/or chronic use of nonsteroidal anti-inflammatory agents; gallium nitrate; lithium; penicillamine) should be avoided if possible. Renal function tests including serum creatinine, serum phosphorous, estimated creatinine clearance, urine glucose, and urine protein should be performed prior to and during therapy with tenofovir. Patients with renal insufficiency at baseline or during treatment may require dosage adjustment in accordance with the manufacturer's product labeling. Persistent or worsening bone pain, pain in extremities, fractures, and/or muscular pain or weakness may also be manifestations of proximal renal tubulopathy and should prompt an evaluation of renal function in at-risk patients.

MONITOR: Coadministration with ritonavir, with or without lopinavir, has been suggested in postmarketing reports to increase the proximal tubular intracellular concentrations of tenofovir and potentiate the risk of tenofovir-induced nephrotoxicity. The proposed mechanism is ritonavir inhibition of tenofovir renal tubular secretion into the urine via multidrug resistance protein MRP2. Analysis of data from a compassionate access study in which 271 patients with advanced HIV disease received the combination for a mean duration of 63 weeks revealed no clinically significant nephrotoxicity associated with coadministration. However, there have been case reports of renal failure associated with acute tubular necrosis, Fanconi's syndrome, and nephrogenic diabetes insipidus in patients treated with tenofovir disoproxil fumarate in combination with ritonavir. Some patients had incomplete recovery of renal function more than a year after cessation of tenofovir therapy. Ritonavir given in combination with lopinavir has also been reported to modestly increase the plasma concentrations of tenofovir. In contrast, both slight decreases and no change in lopinavir and ritonavir concentrations have been reported.

MANAGEMENT: Caution is advised if tenofovir disoproxil fumarate is prescribed with ritonavir. Renal function should be monitored regularly, including surveillance for signs of tubulopathy such as glycosuria, acidosis, increases in serum creatinine level, electrolyte disturbances (e.g., hypokalemia, hypophosphatemia), and proteinuria. The same precaution may be applicable during therapy with other protease inhibitors based on their similar pharmacokinetic profile, although clinical data are lacking. Nelfinavir reportedly does not alter the pharmacokinetics of tenofovir, or vice versa. Tenofovir administration should be discontinued promptly if nephropathy develops.

MONITOR: Coadministration with ritonavir, with or without lopinavir, has been suggested in postmarketing reports to increase the proximal tubular intracellular concentrations of tenofovir and potentiate the risk of tenofovir-induced nephrotoxicity. The proposed mechanism is ritonavir inhibition of tenofovir renal tubular secretion into the urine via multidrug resistance protein MRP2. Analysis of data from a compassionate access study in which 271 patients with advanced HIV disease received the combination for a mean duration of 63 weeks revealed no clinically significant nephrotoxicity associated with coadministration. However, there have been case reports of renal failure associated with acute tubular necrosis, Fanconi's syndrome, and nephrogenic diabetes insipidus in patients treated with tenofovir disoproxil fumarate in combination with ritonavir. Some patients had incomplete recovery of renal function more than a year after cessation of tenofovir therapy. Ritonavir given in combination with lopinavir has also been reported to modestly increase the plasma concentrations of tenofovir. In contrast, both slight decreases and no change in lopinavir and ritonavir concentrations have been reported.

MANAGEMENT: Caution is advised if tenofovir disoproxil fumarate is prescribed with ritonavir. Renal function should be monitored regularly, including surveillance for signs of tubulopathy such as glycosuria, acidosis, increases in serum creatinine level, electrolyte disturbances (e.g., hypokalemia, hypophosphatemia), and proteinuria. The same precaution may be applicable during therapy with other protease inhibitors based on their similar pharmacokinetic profile, although clinical data are lacking. Nelfinavir reportedly does not alter the pharmacokinetics of tenofovir, or vice versa. Tenofovir administration should be discontinued promptly if nephropathy develops.

GENERALLY AVOID: Lopinavir in combination with ritonavir may cause dose-related prolongation of the QT interval. 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. In a study of 39 healthy adults who were administered lopinavir-ritonavir at a therapeutic dosage of 400 mg-100 mg twice daily and a supratherapeutic dosage of 800 mg-200 mg twice daily, the maximum mean time-matched difference in QTcF interval from placebo (after baseline correction) was 5.3 msec for the lower dosage and 15.2 msec for the supratherapeutic dosage in the 12 hours post-dose on treatment day 3 when exposures were approximately 1.5 and 3-fold higher, respectively, than those observed with recommended once-daily or twice-daily dosages of lopinavir-ritonavir at steady state. No subject experienced an increase in QTcF greater than 60 msec from baseline or a QTcF interval exceeding the potentially clinically relevant threshold of 500 msec. There have been cases of QT interval prolongation and torsade de pointes arrhythmia during postmarketing use of lopinavir-ritonavir, although causality could not be established. In general, the risk of an individual agent or a combination of 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: Coadministration of lopinavir-ritonavir with other drugs that can prolong the QT interval should generally be avoided. Patients treated with any medication that can cause QT prolongation 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.