Tikosyn

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Tikosyn Administration

  1. Before initiating TIKOSYN therapy, previous antiarrhythmic therapy should be withdrawn for a minimum of 3 plasma half-lives. TIKOSYN should not be initiated following amiodarone therapy until amiodarone plasma levels are below 0.3 mcg/mL or until amiodarone has been withdrawn for at least 3 months.
  2. Patients with atrial fibrillation should be anticoagulated according to usual medical practice.
  3. Admit patient to the telemetry unit; choose a telemetry lead with a visible QT interval. All measurements of the QT interval should be from this lead.
  4. Telemetry monitoring should continue for a minimum of 3 days or for 12 hours after conversion to normal sinus rhythm, whichever is longer.
  5. The concomitant use of verapamil, hydrochlorothiazide (alone or in combination, such as with triamterene), or the cation transport system inhibitors cimetidine, trimethoprim (alone or in combination with sulfamethoxazole), and ketoconazole with TIKOSYN is contraindicated, as each drug causes a substantial increase in dofetilide plasma concentration. In addition, other known inhibitors of the renal cation transport system, such as prochlorperazine and megestrol, should not be used in patients on TIKOSYN.
  6. CAUTION should be used when coadministering TIKOSYN with macrolide antibiotics, azole antifungals, protease inhibitors, and SRIs, as these agents may increase blood levels of TIKOSYN.
  7. Concomitant administration of TIKOSYN and digoxin is permitted. Carefully monitor patients for the signs and symptoms of digoxin toxicity. The concomitant administration of digoxin was associated with a higher occurrence of torsades de pointes. It is not clear whether this represents an interaction with TIKOSYN or the presence of more severe structural heart disease in patients taking digoxin.
  8. If potassium (K+) is <4.0 mEq/L, replace K+ before administration of TIKOSYN.
  9. Before administering the first dose of TIKOSYN on Day 1, measure the QTc interval (determine the QT if the heart rate is <60 bpm or >100 bpm).
    1. If baseline QTc is >440 msec (500 msec in patients with ventricular conduction abnormalities), TIKOSYN is CONTRAINDICATED; if =440 msec, you may proceed.
    2. Note time, date, and the telemetry lead on the strip.
    3. All measurements of the QTc interval should be from this lead.
  10. Measure the QT interval (determine QTc) 2-3 hours after each dose of TIKOSYN until the patient is discharged.
  11. Determine the patient’s actual body weight in kg.
  12. Measure patient’s serum creatinine level as mg/dL.
  13. Calculate patient’s creatinine clearance using the following formula: 
Males:    (140-age)(actual body weight in kg)/(72)(creatinine clearance in mg/dL)
Females:    (140-age)(actual body weight in kg)/(72)(creatinine clearance in mg/dL)x 0.85

Dosing

  1. The creatinine clearance results should be received by the pharmacy to dispense the first TIKOSYN dose.
  2. If the calculated creatinine clearance is <20 mL/min, TIKOSYN is CONTRAINDICATED.
  3. If the calculated creatinine clearance is >60 mL/min, the appropriate dose of TIKOSYN is 500 mcg BID.
    1. 2-3 hours after the initial dose, if QTc increases to >15% from baseline, then decrease TIKOSYN to 250 mcg BID.
  4. If the calculated creatinine clearance is between 40 mL/min and 60 mL/min, the appropriate dose of TIKOSYN is 250 mcg BID.
    1. 2-3 hours after the initial dose, if QTc increases to >15% from baseline, then decrease TIKOSYN to 125 mcg BID.
    2. If QTc increases to >500 msec (550 msec in the presence of a ventricular conduction abnormality), TIKOSYN should be decreased to 125 mcg BID.
  5. If the calculated creatinine clearance is 20 mL/min to <40 mL/min, the appropriate dose of TIKOSYN is 125 mcg BID.
    1. >2-3 hours after the initial dose, if QTc increases to >15% from baseline, then decrease TIKOSYN to 125 mcg QD.
    2. If QTc increases to >500 msec (550 msec in the presence of a ventricular conduction abnormality), then decrease TIKOSYN to 125 mcg QD.

POSTDOSE ADJUSTMENTS

  1. The second dose of TIKOSYN should only be given after the QT has been determined. Only 1 down titration of TIKOSYN for QTc is suggested. If QTc is still excessively prolonged, DISCONTINUE TIKOSYN therapy.
  2. During therapy initiation in the hospital, at 2-3 hours after each dose of TIKOSYN, determine the QTc to see if dose adjustment is necessary.
    1. Response to QT measurement after the first dose:
    2. If QTc increases by >15% or is >500 msec (550 msec in the presence of a ventricular conduction abnormality), decrease the TIKOSYN dose as described above.
    3. Response to QT measurement after subsequent doses:
    4. If after subsequent doses the absolute QT is >500 msec (550 msec in the presence of a ventricular conduction abnormality), TIKOSYN should be DISCONTINUED.
  3. TIKOSYN should be given q12h (actual times may vary according to local hospital practice; the doses should be given at the same time each day, ie, 12 hours apart); QD TIKOSYN should be given at the same time every day. The risk of torsades de pointes is related to dose as well as to patient characteristics. Physicians may, therefore, in some cases, choose doses lower than determined by the algorithm. If at any time this lower dose is increased, the patient needs to be rehospitalized for 3 days. Previous toleration of higher doses does not eliminate the need for rehospitalization.
  4. After the third TIKOSYN dose, call the mail order pharmacy number (1-800-238-7828) to place the outpatient prescription. The physician who orders a TIKOSYN prescription must be a confirmed participant of a TIKOSYN education program. You will need the patient’s final dose of TIKOSYN, patient’s full name (correct spelling), address, insurer, and physician’s name. If the TIKOSYN dose is changed or discontinued after the prescription has been faxed, please notify the mail order pharmacy immediately.
  5. Contact your hospital pharmacy to order a TIKOSYN bottle with 14 capsules of the final dosage strength.* The patient should be discharged with this bottle to ensure a sufficient drug supply before the first order from the mail order or retail pharmacy is supplied.
    1. This bottle is supplied free of charge to hospitals.

ACTIONS PRIOR TO PATIENT DISCHARGE

  1. Ensure the patient received the TIKOSYN discharge bottle with 14 capsules.
  2. Counsel your patient to use the tools in the TIKOSYN Patient Resource Kit.
  3. Alert patients that blood work and ECG will be re-evaluated every 3 months by their doctor to check the renal function and the QTc.
    1. If QTc exceeds 500 msec (550 msec in patients with ventricular conduction abnormalities), TIKOSYN therapy should be discontinued and patients should be carefully monitored until QTc returns to baseline levels. If renal function deteriorates, adjust dose as described in steps 16-18 under "Dosing Overview."
  4. Inform the patient’s general practitioner (GP) that the patient is now on TIKOSYN. Important points to mention include:
    1. TIKOSYN is contraindicated with verapamil, hydrochlorothiazide (alone or in combination, such as with triamterene), and cation transport inhibitors such as cimetidine, ketoconazole, trimethoprim (alone or in combination with sulfamethoxazole), prochlorperazine, and magestrol.
    2. Renal function and QTc should be re-evaluated every 3 months or as medically warranted.
    3. TIKOSYN is only available through 1 central pharmacy; the drug will be shipped directly to the patient. If the GP would like to write a refill for the patient, he or she must be a confirmed participant in a TIKOSYN educational program before the central pharmacy can fill the prescription. The GP can learn how to do this by calling 1-877-TIKOSYN (845-6796). Alternatively, the GP can continue to see the patient in consultation with a physician who is a confirmed participant in a TIKOSYN educational program.
    4. On receipt of patient information, the GP should read the enclosed package insert for more information. The most serious side effect of TIKOSYN is torsades de pointes. The most common side effects with TIKOSYN occurred at rates similar to placebo and included headache, chest pain, and dizziness.
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