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Tikosyn: A new Class III antiarrhythmic
By Lorelei Bynum,
PharmD*
Auburn University
(*Written as a PharmD candidate)
Dofetilide (Tikosyn) is a Class III antiarrhythmic drug approved by the Food and Drug Administration in April 1999. It is indicated for the conversion of atrial fibrillation and atrial flutter to normal sinus rhythm. It also is indicated for the maintenance of normal sinus rhythm in patients with atrial fibrillation or atrial flutter of more than one-week duration who have been converted to normal sinus rhythm.
Because Tikosyn can cause life-threatening ventricular arrhythmias, it should be reserved for patients with highly symptomatic atrial fibrillation or atrial flutter. It has not been shown to be effective in patients with paroxysmal atrial fibrillation, ventricular tachycardia, or ventricular fibrillation.
This medication is available only to hospitals and prescribers who have received the appropriate Tikosyn education. At this time, it continues to be available only to the patient through one mail-order pharmacy and is not available in community pharmacies.
Because Tikosyn can cause serious ventricular arrhythmias, primarily torsades de pointes, patients initiated or re-initiated on it must be placed in the hospital, which can provide continuous ECG monitoring, for three days. Because of the serious side effects of this medication and because of drug interactions, Tikosyn must be initiated according to important guidelines. The QTc interval must be determined before initiating Tikosyn. The dose must be based on the patient’s renal function. Creatinine clearance must be calculated for all patients to determine starting dose; patient factors such as SCr and weight also should be examined to verify that the calculated creatinine clearance is correct for each patient.
After giving the first dose, there should be continuous ECG monitoring; the QTc interval should be measured again at two to three hours after the first dose to determine if dosage adjustment is needed. The QTc interval also should be measured two to three hours after each subsequent dose while the patient is in the hospital.
After the first several doses of Tikosyn, the physician will need to notify the hospital pharmacy to order a seven-day supply of the medication in the final dosage strength for the patient to take home. The physician also will need to call the mail-order pharmacy (800-238-7828) to order the medication for the patient because Tikosyn is only available through one mail-order pharmacy and not through community pharmacies.
Renal function and QTc interval should be monitored approximately every three months to assess if a change in dosage is needed. Patients should be counseled on this medication before being discharged from the hospital because of the serious side effects and drug interactions that can occur. The patient’s general practitioner and community pharmacy also must be notified that the patient is taking Tikosyn so they can monitor for any drug interactions with the patients’ medications. It is important that the use of this medication be monitored by physicians, nurses, and pharmacists and by the patients receiving it.
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