Lidocaine/oxytetracycline 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.

Clostridioides difficile-associated diarrhea (CDAD), formerly pseudomembranous colitis, has been reported with almost all antibacterial drugs and may range from mild diarrhea to fatal colitis. The most common culprits include clindamycin and lincomycin. Antibacterial therapy alters the normal flora of the colon, leading to overgrowth of C difficile, whose toxins A and B contribute to CDAD development. Morbidity and mortality are increased with hypertoxin-producing strains of C difficile; these infections can be resistant to antimicrobial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea after antibacterial use. Since CDAD has been reported to occur more than 2 months after antibacterial use, careful medical history is necessary. Therapy with broad-spectrum antibacterials and other agents with significant antibacterial activity should be administered cautiously in patients with history of gastrointestinal disease, particularly colitis; pseudomembranous colitis (generally characterized by severe, persistent diarrhea and severe abdominal cramps, and sometimes associated with the passage of blood and mucus), if it occurs, may be more severe in these patients and may be associated with flares in underlying disease activity. Antibacterial drugs not directed against C difficile may need to be stopped if CDAD is suspected or confirmed. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C difficile, and surgical evaluation should be started as clinically indicated.

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.

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.

Oxytetracycline is partially removed by hemodialysis. Doses should either be scheduled for administration after dialysis or supplemental doses be given after dialysis.

The use of tetracyclines has rarely been associated with hepatotoxicity. Histologic fatty changes of the liver, elevated liver enzymes, and jaundice have been reported, primarily in patients treated with large doses of intravenous tetracycline hydrochloride (no longer available in the U.S.) but also in patients receiving high oral doses of these drugs. Therapy with tetracyclines should be administered cautiously in patients with preexisting liver disease or biliary obstruction. Reduced dosages may be appropriate, particularly with minocycline and doxycycline, since the former is metabolized by the liver and the latter undergoes enterohepatic recycling. Liver function tests are recommended prior to and during therapy, and the concomitant use of other potentially hepatotoxic drugs should be avoided.

Tetracyclines (except doxycycline) are eliminated by the kidney to various extent. Patients with renal impairment may be at greater risk for tetracycline-associated hepatic and/or renal toxicity (increased BUN with consequent azotemia, hyperphosphatemia, and acidosis) due to decreased drug clearance. Therapy with tetracyclines should be administered cautiously at reduced dosages in patients with renal impairment. Clinical monitoring of renal and liver function is recommended, and serum tetracycline levels may be necessary during prolonged therapy.

The use of oral tetracycline capsules and tablets has been associated with esophageal irritation and ulceration in patients who ingested the drug without sufficient fluid shortly before bedtime. Therapy with solid formulations of tetracyclines should preferably be avoided in patients with esophageal obstruction, compression or dyskinesia. If the drugs are used, patients should be advised not to take the medication just before retiring and to drink fluids liberally.