Drug Interactions between dexamethasone / ketorolac / moxifloxacin and levoketoconazole

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.

GENERALLY AVOID: Use of hepatotoxic drugs together with ketoconazole or levoketoconazole may potentiate the risk of liver injury. Serious hepatotoxicity has been reported with levoketoconazole and hepatotoxicity requiring liver transplantation has been reported with the use of oral ketoconazole, of which levoketoconazole is an enantiomer. Some patients had no risk factors for liver disease. During clinical studies, drug-induced liver injury (peak ALT or AST greater than 3 times the upper limit of normal) occurred in 13% of patients using levoketoconazole.

MANAGEMENT: The use of ketoconazole or levoketoconazole with other potentially hepatotoxic agents should be avoided. Patients treated with levoketoconazole or ketoconazole should have liver tests performed prior to and during treatment. Levoketoconazole manufacturer recommends interrupting treatment immediately if signs of hepatotoxicity occur. Refer to levoketoconazole labeling for specific instructions on management of hepatotoxicity. 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.

CONTRAINDICATED: Levoketoconazole can cause concentration-dependent, life-threatening prolongation of the QT interval. Coadministration with other agents that can prolong the QT interval may increase the risk of ventricular arrhythmias including torsade de pointes and sudden death. According to cardiac electrophysiology data provided by the prescribing information, the largest mean increase in QTc was 24 msec following administration of levoketoconazole 150 mg to 600 mg twice daily in patients with endogenous Cushing's syndrome, and the increase was dose-related. During two premarketing levoketoconazole clinical studies, 4 (2.4%) patients experienced QTcF greater than 500 msec, and 23 (14.7%) patients presented a change in QTcF greater than 60 msec from baseline. The clinical studies did not include patients with baseline QTcF interval greater than 470 msec. 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 levoketoconazole with other drugs that can prolong the QT interval is considered contraindicated.

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 inhibitors of CYP450 3A4 may increase the plasma concentrations and pharmacologic effects of corticosteroids, which are primarily metabolized by the isoenzyme. The interaction has been reported with potent inhibitors such as clarithromycin, erythromycin, itraconazole, nefazodone, cobicistat, and ritonavir during concomitant use of various corticosteroids, including inhaled, nasal, and ophthalmic formulations. Systemic corticosteroid adverse effects may occur following intensive or long-term continuous ophthalmic corticosteroid therapy. Cushing's syndrome and adrenal insufficiency have been attributed to the interaction.

MANAGEMENT: The possibility of increased corticosteroid effects should be considered during coadministration with potent and moderate CYP450 3A4 inhibitors. Some authorities advise against concomitant use unless the potential benefit outweighs the risk. If the combination is considered necessary, a lower dosage of the corticosteroid may be required. When indicated for intranasal or inhalational use, alternative corticosteroids such as beclomethasone, which is less dependent on CYP450 3A4 metabolism, should be considered, particularly if long term treatment is required. Patients should be monitored for signs and symptoms of hypercorticism such as acne, striae, thinning of the skin, easy bruising, moon facies, dorsocervical "buffalo" hump, truncal obesity, increased appetite, acute weight gain, edema, hypertension, hirsutism, hyperhidrosis, proximal muscle wasting and weakness, glucose intolerance, exacerbation of preexisting diabetes, depression, and menstrual disorders. Other systemic glucocorticoid effects may include adrenal suppression, immunosuppression, posterior subcapsular cataracts, glaucoma, bone loss, and growth retardation in children and adolescents. Following extensive use with a potent CYP450 3A4 inhibitor, a progressive dosage reduction may be required over a longer period if the corticosteroid is to be withdrawn from therapy, as there may be a significant risk of adrenal suppression. Signs and symptoms of adrenal insufficiency include anorexia, hypoglycemia, nausea, vomiting, weight loss, muscle wasting, fatigue, weakness, dizziness, postural hypotension, depression, and adrenal crisis manifested as inability to respond to stress (e.g., illness, infection, surgery, trauma).

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.