Drug Interactions between Decadron with Xylocaine and etanercept

MONITOR CLOSELY: The use of tumor necrosis factor (TNF) blockers with other immunosuppressive or myelosuppressive agents may increase the risk of infections. Serious infections and sepsis, including fatalities, have been reported with the use of TNF blockers, particularly in patients on concomitant immunosuppressive therapy. Agents that may be significantly myelo- or immunosuppressive include antineoplastic agents, radiation, zidovudine, linezolid, some antirheumatic agents, high dosages of corticosteroids or adrenocorticotropic agents (greater than 10 mg/day to 1 mg/kg/day, whichever is less, of prednisone or equivalent for more than 2 weeks), and long-term topical or inhaled corticosteroids. Concomitant use of TNF blockers with other immunosuppressants such as azathioprine or mercaptopurine may also increase the risk of a rare and often fatal cancer of white blood cells known as hepatosplenic T-Cell lymphoma (HSTCL), which has primarily been reported in adolescent and young adult males receiving treatment for Crohn's disease or ulcerative colitis. Cases of HSTCL have also occurred during use of these agents alone. Because individuals with rheumatoid arthritis, Crohn's disease, ankylosing spondylitis, psoriatic arthritis, or plaque psoriasis may be more likely to develop lymphoma than the general population, it is difficult to assess the added risk of TNF blockers, azathioprine, and/or mercaptopurine.

MANAGEMENT: Patients receiving a TNF blocker alone or with other immunosuppressive or myelosuppressive agents should be monitored closely for the development of infections. TNF blocker therapy should be discontinued if a serious infection or sepsis occurs. Close monitoring for signs and symptoms of HSTCL (e.g., splenomegaly, hepatomegaly, abdominal pain, persistent fever, night sweats, weight loss) is also recommended during use of TNF blockers, particularly in combination with other immunosuppressants such as azathioprine and mercaptopurine.

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MONITOR: Plasma concentrations of drugs that are CYP450 substrates may decrease following the initiation of interleukin (IL) inhibitors, tumor necrosis factor (TNF) blockers, or interferon (IFN) inhibitors in patients with chronic inflammatory diseases. Because the formation of hepatic CYP450 enzymes is down-regulated during infection and chronic inflammation by increased levels of certain cytokines (e.g., interleukins-1, -6, and -10; tumor necrosis factor alpha; interferons), treatment targeting these cytokines may restore or normalize CYP450 enzyme levels resulting in increased metabolism of these drugs. In vitro studies showed that tocilizumab, an IL-6 inhibitor, has the potential to impact expression of various hepatic microsomal enzymes including CYP450 1A2, 2B6, 2C9, 2C19, 2D6, and 3A4. Its effects on CYP450 2C8 or transporters is unknown. In vivo studies with omeprazole (a substrate of CYP450 2C19 and 3A4) and simvastatin (a substrate of CYP450 3A4 and OATP 1B1) showed decreases of up to 28% and 57% in systemic exposure, respectively, one week following a single dose of tocilizumab. Likewise, simvastatin and simvastatin acid exposures decreased by 45% and 36%, respectively, in 17 patients with rheumatoid arthritis one week following a single 200 mg subcutaneous dose of sarilumab, another IL-6 inhibitor. A role for other interleukins such as IL-12, IL-17A, or IL-23 in the regulation of CYP450 enzymes has not been established, and it is not known whether antagonists of these interleukins would similarly affect CYP450 metabolism. Risankizumab and tildrakizumab, both IL-23 antagonists, demonstrated no clinically significant effects when tested with CYP450 probe substrates such as caffeine (1A2), warfarin (2C9), omeprazole (2C19), dextromethorphan (2D6), metoprolol (2D6), and midazolam (3A4) in study subjects with plaque psoriasis.

MANAGEMENT: Caution is advised when treatments targeting cytokines such as interleukins, tumor necrosis factors, or interferons are prescribed to patients receiving concomitant drugs that are CYP450 substrates, particularly those with narrow therapeutic ranges (e.g., antiarrhythmics, anticonvulsants, immunosuppressants, theophylline) or sensitive substrates where decreases in plasma levels may be significant or undesirable (e.g., oral contraceptives, statins, benzodiazepines, opioids). Clinical and/or laboratory monitoring should be considered following the initiation or withdrawal of such treatments, and the dosage(s) of the CYP450 substrate(s) adjusted accordingly. Clinicians should note that the effects of IL inhibitors, TNF blockers, and IFN inhibitors on CYP450 activities may persist for several weeks after stopping therapy.

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Coadministration with inducers of CYP450 1A2 and/or 3A4 may decrease the plasma concentrations of lidocaine, which is primarily metabolized by these isoenzymes. In four healthy volunteers (2 smokers and 2 nonsmokers), administration of a single 400 mg oral dose of lidocaine following pretreatment with the CYP450 inducer phenobarbital (15 mg/day for 4 weeks, followed by 30 mg/day for 4 weeks) decreased lidocaine systemic exposure (AUC) by 37% and increased its oral clearance by 56% compared to administration of lidocaine alone. In another study, the mean bioavailability of a single 750 mg oral dose of lidocaine in six patients receiving chronic antiepileptic drug therapy (consisting of one or more of the following enzyme-inducing anticonvulsants: phenobarbital, primidone, phenytoin, carbamazepine) was approximately 2.5-fold lower than that reported for six healthy control subjects, while intrinsic clearance was nearly threefold higher. By contrast, the interaction was modest for lidocaine administered intravenously, suggesting induction of primarily hepatic first-pass rather than systemic metabolism of lidocaine. When a single 100 mg dose of lidocaine was given intravenously, mean lidocaine AUC was reduced by less than 10% and serum clearance increased by just 17% in the epileptic patients compared to controls. These changes were not statistically significant. Likewise, mean lidocaine AUC decreased by approximately 11% and plasma clearance increased by 15% when a single 50 mg intravenous dose of lidocaine was administered following pretreatment with the potent CYP450 inducer rifampin (600 mg/day for six days) in ten healthy, nonsmoking male volunteers. Another pharmacokinetic study found that cigarette smoke, an inducer of CYP450 1A2, reduced the bioavailability of lidocaine when administered orally, but had only minor effects on lidocaine administered intravenously. When 4 smokers and 5 non-smokers received 2 doses of lidocaine (100 mg IV followed by 100 mg orally after a 2-day washout period), the smoker's systemic exposure (AUC) of oral lidocaine was 68% lower than non-smokers. The AUC of IV lidocaine was only 9% lower in smokers compared with non-smokers. The clinical impact of smoking on lidocaine has not been studied, however, a loss of efficacy may occur.

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