Drug Interactions between dexamethasone / ketorolac / moxifloxacin and panobinostat

MONITOR CLOSELY: Concomitant administration of corticosteroids may potentiate the risk of tendinitis and tendon rupture associated with fluoroquinolone treatment. The mechanism is unknown. Tendinitis and tendon rupture have most frequently involved the Achilles tendon, although cases involving the rotator cuff (the shoulder), the hand, the biceps, and the thumb have also been reported. Some have required surgical repair or resulted in prolonged disability. Tendon rupture can occur during or up to several months after completion of fluoroquinolone therapy.

MANAGEMENT: Caution is recommended if fluoroquinolones are prescribed in combination with corticosteroids, particularly in patients with other concomitant risk factors (e.g., age over 60 years; recipient of kidney, heart, and/or lung transplant). Patients should be advised to stop taking the fluoroquinolone, avoid exercise and use of the affected area, and promptly contact their physician if they experience pain, swelling, or inflammation of a tendon. In general, fluoroquinolones should only be used to treat conditions that are proven or strongly suspected to be caused by bacteria and only if the benefits outweigh the risks.

MONITOR CLOSELY: Coadministration of panobinostat and drugs that interfere with platelet function or coagulation may potentiate the risk of bleeding complications. Treatment with panobinostat has been associated with severe thrombocytopenia and hemorrhage (including gastrointestinal and pulmonary hemorrhage) with fatal outcomes. The risk may be increased in patients with coagulation disorders or those on chronic anticoagulation therapy. In a phase III clinical trial in patients with relapsed multiple myeloma, treatment-emergent grade 3 to 4 (CTCAE) thrombocytopenia and hemorrhage was reported in 67% and 4.2% of panobinostat-treated patients, respectively. In the same phase III clinical trial, there were 5 patients treated with panobinostat who died due to a hemorrhagic event, compared to 1 in the control arm. The patients with fatal bleeding events reported in the clinical trial had at least grade 3 (CTCAE) thrombocytopenia at the time of the event.

MANAGEMENT: Concomitant use of other medications that interfere with platelet function or coagulation should be considered cautiously in patients treated with panobinostat. Close clinical and laboratory observation for bleeding complications is recommended during therapy. A complete blood cell count should be performed prior to and at least weekly during treatment according to treatment protocols, including monitoring for thrombocytopenia. Dose modifications may be required based on individual patient tolerability. Patients should be advised to promptly report any signs of bleeding to their doctor, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools. Since panobinostat is indicated in combination with bortezomib and dexamethasone, the manufacturer labeling for these products should also be consulted for additional information.

GENERALLY AVOID: Panobinostat can cause dose-dependent 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 premarketing multiple myeloma trial, QTc prolongation with values between 451 to 480 msec and between 481 to 500 msec occurred in 10.8% and 1.3% of patients receiving panobinostat, respectively. A maximum QTcF increase from baseline of 31 to 60 msec and greater than 60 msec was observed in 14.5% and 0.8% of panobinostat-treated patients, respectively. No episodes of QTcF prolongation exceeding 500 msec were reported with panobinostat given at a dose of 20 mg in combination with bortezomib and dexamethasone in the multiple myeloma trial. Pooled clinical data from over 500 patients treated with panobinostat monotherapy at different dose levels for various indications have shown that the incidence of CTC Grade 3 QTc prolongation (i.e., QTcF >500 msec) was approximately 1% overall and 5% or more at a dose of 60 mg or higher. 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, hypocalcemia). Moreover, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).

MANAGEMENT: Concomitant use of panobinostat with other drugs that can prolong the QT interval should generally be avoided. Anti-emetic drugs with known QT prolonging risk such as dolasetron, granisetron, ondansetron, palonosetron, and tropisetron may be used with frequent ECG monitoring. ECG and serum electrolytes, including potassium, magnesium and calcium, should be monitored before starting panobinostat therapy and periodically during treatment as clinically indicated. In the premarketing trial, ECGs were performed at baseline and prior to initiation of each cycle for the first 8 cycles. Panobinostat should not be started if baseline QTc is greater than 450 msec. Likewise, treatment should be interrupted in patients who develop QTc prolongation of 480 msec or greater until recovery to less than or equal to Grade 1, then resumed at a reduced dose. In case of recurrence, therapy should be withheld until recovery to less than or equal to Grade 1, then resumed at a further reduced dose if necessary. Permanently discontinue panobinostat therapy if Grade 3 or 4 QTc prolongation does not resolve. 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.

MONITOR: The combined use of corticosteroids and nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the potential for serious gastrointestinal (GI) toxicity, including inflammation, bleeding, ulceration, and perforation. In a large, case-control study of elderly patients, those who used corticosteroids and NSAIDs concurrently had an estimated relative risk (RR) for peptic ulcer disease and GI hemorrhage of 14.6 compared to those who used neither. Corticosteroid use was associated with a doubling of the risk (estimated RR = 2.0), but the risk was confined to those who also used NSAIDs. It is possible that both categories of agents are ulcerogenic and have additive effects on the GI mucosa during coadministration. Some investigators have also suggested that the primary effect of corticosteroids in this interaction is to delay healing of erosions caused by NSAIDs rather than cause de novo ulcerations.

MANAGEMENT: Caution is advised if corticosteroids and NSAIDs are used together, especially in patients with a prior history of peptic ulcer disease or GI bleeding and in elderly and debilitated patients. During concomitant therapy, patients should be advised to take the medications with food and to immediately report signs and symptoms of GI ulceration and bleeding such as severe abdominal pain, dizziness, lightheadedness, and the appearance of black, tarry stools. The selective use of prophylactic anti-ulcer therapy (e.g., antacids, H2-antagonists) may be considered.

MONITOR: Coadministration with inducers of CYP450 3A4 may decrease the plasma concentrations of panobinostat, which is partially metabolized by the isoenzyme. The interaction has not been evaluated clinically, but simulations using physiologically-based pharmacokinetic (PBPK) models suggest an approximately 70% decrease in panobinostat systemic exposure in the presence of potent CYP450 3A4 inducers.

MANAGEMENT: Caution is advised during concomitant use of panobinostat with CYP450 3A4 inducers. The potential for decreased efficacy of panobinostat should be considered.

MONITOR: Coadministration with nonsteroidal anti-inflammatory drugs (NSAIDs) may potentiate the risk of central nervous system toxicity sometimes associated with fluoroquinolone use. The interaction has been reported most often with enoxacin. It may occur with other fluoroquinolones as well, but is poorly documented. The exact mechanism of interaction is unknown. Some investigators suggest that the piperazine ring of fluoroquinolones may inhibit the binding of gamma-aminobutyric acid (GABA) to brain receptors and that NSAIDs may synergistically add to this effect. Patients with a history of seizures may be at greater risk.

MANAGEMENT: Clinical monitoring for signs of CNS stimulation such as tremors, involuntary muscle movements, hallucinations, or seizures is recommended if fluoroquinolone antibiotics are prescribed in combination with NSAIDs.