Betamethasone/iodixanol/lidocaine Disease Interactions

Antiarrhythmic agents can induce severe hypotension (particularly with IV administration) or induce or worsen congestive heart failure (CHF). Patients with primary cardiomyopathy or inadequately compensated CHF are at increased risk. Antiarrhythmic agents should be administered cautiously and dosage and/or frequency of administration modified in patients with hypotension or adequately compensated CHF. Alternative therapy should be considered unless these conditions are secondary to cardiac arrhythmia.

The immunosuppressant and anti-inflammatory effects of corticosteroids, particularly in higher dosages, may decrease host resistance to infectious agents, decrease the ability to localize infections, mask the symptoms of infection, and reactivate or exacerbate latent infections (e.g., hepatitis B, amebiasis). Secondary infections may be more likely to develop. In general, corticosteroids should not be used in patients with active infections, especially systemic fungal infections, unless they are medically necessary and effective antimicrobial therapy or other appropriate treatment has been instituted. However, for corticosteroid-dependent patients who develop a severe or life-threatening infection, continuation of corticosteroid therapy with at least physiologic replacement dosages should be considered, since these patients may have secondary adrenocortical insufficiency. Removal of external steroid during periods of stress may be detrimental to these patients.

Reports of thyroid storm following the use of iodinated diagnostic agents in patients with hyperthyroidism or with an autonomously functioning thyroid nodule suggest that this additional risk be evaluated in such patients before the use of any contrast medium. Some agents such as ioversol are contraindicated in symptomatic hyperthyroidism.

Lidocaine is rapidly and extensively metabolized by the liver. Less than 10% is eliminated unchanged in the urine. Several inactive and two active forms (MEGX and GX) have been identified. MEGX and GX exhibit antiarrhythmic and convulsant properties. GX accumulates during prolonged intravenous lidocaine infusion. The pharmacokinetic disposition of lidocaine is altered by changes in hepatic function, including hepatic blood flow. Therapy with lidocaine should be administered cautiously and dosing modifications for repeated or loading and maintenance doses may be necessary. Clinical monitoring of cardiac (continuous ECG) is required and serum metabolite concentrations and monitoring hepatic function are recommended.

Lidocaine is primarily eliminated by the kidney. Less than 10% is eliminated unchanged in the urine. Two active metabolites (MEGX and GX) have been identified that exhibit antiarrhythmic and convulsant properties. GX accumulates during prolonged intravenous lidocaine infusion. Serum concentrations of lidocaine and the active metabolites are increased and the half-life prolonged in patients with renal impairment. Therapy with lidocaine should be administered cautiously and dosing modified for repeated or maintenance doses in patients with compromised renal function. Clinical monitoring of cardiac function (continual ECG) is required and serum metabolite concentrations and monitoring renal function are recommended.

Seizures have occurred during lidocaine therapy and have been associated with the rapid administration of a large intravenous doses or accumulation of active metabolites with maintenance therapy. Therapy with lidocaine should be administered cautiously to patients with or predisposed to seizure disorders. Clinical monitoring of cardiac (continuous ECG) is required, and serum metabolite concentrations are recommended.

The use of lidocaine is contraindicated in patients with Stokes-Adam syndrome, Wolff-Parkinson White syndrome, or second- or third-degree AV block in the absence of a functional artificial pacemaker, or congenital QT prolongation.

Administration of radiopaque materials to patients known or suspected of having pheochromocytoma should be performed with extreme caution. If, in the opinion of the physician, the possible benefits of such procedures outweigh the considered risk, the procedures should be performed with the absolute minimum amount of injected radiopaque medium. The blood pressure should be assessed throughout the procedure and measures for treatment of a hypertensive crisis should be available.

Electrolyte imbalance can alter the therapeutic effectiveness of antiarrhythmic agents. Hypokalemia and hypomagnesemia can reduce the effectiveness of antiarrhythmic agents. In some cases, these disorders can exaggerate the degree of QTc prolongation and increase the potential for torsade de pointes. Hyperkalemia can potentiate the toxic effects of antiarrhythmic agents. Electrolyte imbalance should be corrected prior to initiating antiarrhythmic therapy. Clinical monitoring of cardiac function and electrolyte concentrations is recommended.

Some contrast agents have shown to promote the phenomenon of sickling (blood cell rupture) in individuals who are homozygous for sickle cell disease when administered intravenously or intra- arterially. Caution is advised.

In patients with latent tuberculosis or tuberculin reactivity, the use of pharmacologic dosages of corticosteroids may cause a reactivation of the disease. Close monitoring for signs and symptoms of tuberculosis is recommended if corticosteroid therapy is administered to patients with a history of tuberculosis or tuberculin reactivity. During prolonged corticosteroid therapy, tuberculosis chemoprophylaxis may be considered.

Corticosteroids may have enhanced effects on patients with cirrhosis due to decreased metabolism of these agents. Patients with cirrhosis should be monitored more closely for excessive cortisol effects. Dosage adjustments may be required in these patients.

Corticosteroids may aggravate the symptoms of psychosis and emotional instability. Patients with these conditions should be monitored for increased or worsened symptoms during corticosteroid therapy.

Corticosteroids can raise blood glucose level by antagonizing the action and suppressing the secretion of insulin, which results in inhibition of peripheral glucose uptake and increased gluconeogenesis. Therapy with corticosteroids should be administered cautiously in patients with diabetes mellitus, glucose intolerance, or a predisposition to hyperglycemia. Patients with diabetes mellitus should be monitored more closely during corticosteroid therapy, and their antidiabetic regimen adjusted accordingly.

Corticosteroids can cause hypernatremia, hypokalemia, and fluid retention. These mineralocorticoid effects are most significant with fludrocortisone, followed by hydrocortisone and cortisone, then by prednisone and prednisolone. The remaining corticosteroids, betamethasone, dexamethasone, methylprednisolone, and triamcinolone, have little mineralocorticoid activities. However, large doses of any corticosteroid can demonstrate these effects, particularly if given for longer than brief periods. All corticosteroids also increase excretion of calcium and can cause hypocalcemia. Therapy with corticosteroids should be administered cautiously in patients with preexisting electrolyte disturbances. Caution is also advised when treating patients with seizure disorders, since electrolyte disturbances may trigger seizure activity.

Corticosteroids may cause hypernatremia, hypokalemia, fluid retention, and elevation in blood pressure. Large doses of any corticosteroid can demonstrate these effects, particularly if given for longer periods. Therapy with corticosteroids should be administered cautiously in patients with preexisting fluid retention, hypertension, congestive heart failure, and/or renal dysfunction. Dietary sodium restriction and potassium supplementation may be advisable.

Corticosteroids may cause gastrointestinal perforation and hemorrhage, usually when given in high dosages or for prolonged periods. They may also mask symptoms of complications such as peritonitis or intraabdominal sepsis. Therapy with corticosteroids should be avoided or administered cautiously in patients with diverticulitis, nonspecific ulcerative colitis (if there is a probability of impending perforation, abscess, or other pyogenic infection), or recent intestinal anastomoses.

Corticosteroids mimic the effects of endogenous cortisol and aldosterone. Use of these agents may aggravate conditions of hyperadrenocorticalism in a dose-dependent manner.

Corticosteroids may elevate serum triglyceride and LDL cholesterol levels if used for longer than brief periods. Patients with preexisting hyperlipidemia may require closer monitoring during prolonged corticosteroid therapy, and adjustments made accordingly in their lipid-lowering regimen.

Corticosteroids may have enhanced effects in hypothyroidism due to decreased metabolism of these agents. Patients with hypothyroidism should be monitored more closely for excessive cortisol effects. Dosage adjustments may be required secondary to changes in their thyroid condition.

Corticosteroids are primarily metabolized by the liver and may have enhanced effects in patients with liver disease. Dosage adjustments may be necessary in these patients.

The use of corticosteroids may be associated with left ventricular free-wall rupture in patients who have had a recent myocardial infarction. Pharmacologic dosages of corticosteroids should be administered with great caution in such patients.

Although corticosteroids are commonly used in the treatment of myasthenia gravis to increase muscle strength, these agents should nevertheless be administered with caution in such setting. Patients should be treated in an intensive care unit and receive respiratory support, since muscle strength may markedly decrease initially, particularly with high dosages. Preferably, therapy should begin with relatively low dosages (15 to 25 mg/day of prednisone or equivalent) and be increased stepwise as tolerated (approximately 5 mg/day of prednisone or equivalent at 2- to 3-day intervals until marked clinical improvement or a dosage of 50 mg/day is reached). Improvement may be delayed and gradual. Thus, it is important not to discontinue therapy prematurely.

Toxic myopathy has been observed with the chronic use or the administration of large doses of corticosteroids, often in patients with disorders of neuromuscular transmission such as myasthenia gravis or in patients receiving neuromuscular blocking agents. Fluorinated corticosteroids such as betamethasone, dexamethasone, and triamcinolone appear to cause more severe muscle atrophy and weakness than the nonfluorinated agents. Moreover, multiple-daily doses are more toxic than once-daily or, preferably, alternate-day morning doses. Steroid myopathy is generalized and sometimes accompanied by respiratory weakness and dyspnea. In some cases, it has resulted in quadriparesis. Elevations of creatine kinase (CK) may also occur, albeit infrequently. After withdrawal of corticosteroid therapy, recovery may be slow and incomplete. Therapy with corticosteroids should be administered cautiously in patients with preexisting myopathy or myoneural disorders since these conditions may confound the diagnosis of steroid-induced myopathy. The presence of a normal serum CK level, minimal/no changes of myopathy on electromyography, and type 2 muscle fiber atrophy on biopsy are helpful in suggesting steroid-induced weakness. If steroid myopathy is suspected, a dosage reduction or discontinuation of the steroid should be considered.

Pharmacologic dosages of corticosteroids should be used cautiously in patients with ocular herpes simplex because of the risk of corneal perforation. Corticosteroids are not recommended for patients with active ocular herpes simplex.

Prolonged use of corticosteroids may cause posterior subcapsular cataracts and elevated intraocular pressure, the latter of which may lead to glaucoma and/or damage to the optic nerves. Long-term therapy with corticosteroids should be administered cautiously in patients with a history of cataracts, glaucoma, or increased intraocular pressure.

Corticosteroids reduce osteoblastic function and inhibit the absorption of intestinal calcium, which can result in bone resorption and bone loss during prolonged therapy. In addition, bone matrix may be affected by the protein-catabolic effects of corticosteroids, especially when given in high dosages or for prolonged periods, leading to aseptic necrosis and fractures. Long-term or high-dose corticosteroid therapy should be administered cautiously and only if necessary in patients with or at risk for osteoporosis. Adverse skeletal effects may be minimized by alternate-day or intermittent administration. Any patient receiving prolonged therapy with the equivalent of 7.5 mg prednisone/day or more are at risk for glucocorticoid-induced osteoporosis and should be managed according to The American College of Rheumatology (ACR) guidelines.

Corticosteroids may cause peptic ulcer disease and gastrointestinal (GI) hemorrhage, usually when given in high dosages or for prolonged periods. However, even conventional dosages may aggravate symptoms in patients with a history of peptic ulcers. Delayed healing of ulcers has also been reported. Therapy with corticosteroids should be avoided or administered cautiously in patients with active or latent peptic ulcers or other risk factors for GI bleeding. Some clinicians recommend the use of prophylactic antacids or H2-antagonists between meals when large doses of corticosteroids are necessary.

In patients with scleroderma, corticosteroids may precipitate renal crisis with malignant hypertension, possibly via steroid-induced increases in renin substrate and angiotensin II levels and decreases in vasodilator prostaglandin production. Renal failure may ensue. Therapy with corticosteroids should be administered cautiously in patients with scleroderma. In addition, they should be limited to short-term use.

Unlike most helminths, Strongyloides stercoralis has the ability to replicate in the human host. In patients with strongyloidiasis, the use of pharmacologic or immunosuppressive dosages of corticosteroids may result in Strongyloides hyperinfection and dissemination with widespread larval migration, often accompanied by severe enterocolitis and potentially fatal gram-negative septicemia. Therapy with corticosteroids should be administered with extreme caution, if at all, in these patients. For patients on corticosteroids who develop known or suspected Strongyloides infestation, withdrawal of corticosteroids or reduction of the dose of corticosteroids is recommended.

Corticosteroids may increase blood coagulability and have rarely been associated with the development of intravascular thrombosis, thromboembolism, and thrombophlebitis. Therapy with corticosteroids should be administered cautiously in patients who have or may be predisposed to thrombotic or thromboembolic disorders.

A definite risk exists in the use of intravascular contrast agents in patients who are known to have multiple myeloma. In such cases, anuria has developed resulting in progressive uremia, renal failure and eventually death. Although neither the contrast agent nor dehydration has separately proved to be the cause of anuria in myeloma, it has been speculated that the combination of both may be causative factors. The risk in patients with myeloma is not a contraindication to the procedure; however, partial dehydration in the preparation of these patients for the examination is not recommended since this may predispose to precipitation of myeloma protein in the renal tubules. Myeloma, which occurs most commonly in persons over 40, should be considered before instituting intravascular administration of contrast agents.

The administration of iodinated contrast media may aggravate the symptoms of myasthenia gravis. Caution is advised when using these agents in patients with this condition.

In patients with advanced renal disease, iodinated contrast media should be used with caution, and only when the need for the examination dictates, since the excretion of the medium may be impaired. Patients with combined renal and hepatic disease, severe hypertension or congestive heart failure, and those with recent renal transplant may present an additional risk.

Iodixanol can cause life-threatening or fatal hypersensitivity reactions including anaphylaxis. Manifestations include respiratory arrest, laryngospasm, bronchospasm, angioedema, and shock. Most severe reactions develop shortly after the start of the injection (within 3 minutes), but reactions can occur up to hours later. There is an increased risk in patients with a history of a previous reaction to a contrast agent, and known allergies (i.e., bronchial asthma, drug, or food allergies) or other hypersensitivities. Premedication with antihistamines or corticosteroids does not prevent serious life-threatening reactions, but may reduce both their incidence and severity. Obtain a history of allergy, hypersensitivity, or hypersensitivity reactions to iodinated contrast agents and always have emergency resuscitation equipment and trained personnel available prior to iodixanol administration. Monitor all patients for hypersensitivity reactions.