Dofetilide (Tikosyn)

Jennifer Blake, PharmD, BCPSVicki Lindgren, RN, MSN, CNS, CCRN, CCNS

2011

Objectives• Understand the purpose and side

effects of Tikosyn• Verbalize nursing actions for

patients on Tikosyn• State procedure for Tikosyn

administration

Indications & Contraindications• Indications:

– Maintenance of NSR– Conversion of A-fib or A-flutter to NSR

*** Has not been shown to be effective in patients with paroxysmal A-fib

• Contraindications:– Patients with congenital or acquired long

QT intervals– Known hypersensitivity to the drug– Kidney disease – if the patient has

serious kidney problems or on dialysis they can not take Tikosyn

Do Not Take Tikosyn With the Following:

• Cimetidine (Tagamet)• Verapamil• Ketoconazole (Nizoral)• Trimethoprim (Prolopirm, Trimpex) • Tirmethoprim & Sulfamethoxazole

(Bactrim, Septra)• Prochlorperazine (Compazine)• Megestrol (Megace)• HCTZ

Warnings

• Can cause serious ventricular arrhythmias– Especially Torsades de Pointes– QT interval prolongation is directly

related to Tikosyn plasma concentration

• Factors that can increase risk – Decreased creatinine clearance

• Minimize risk of induced arrhythmia– Any patient started on, or re-initiated on,

Tikosyn needs to be admitted for 3 days or 12 hrs after conversion to NSR (whichever is longer). Necessary to monitor creatinine clearance and EKG

Potassium & Magnesium

• Potassium levels should be within normal range prior to administering & maintained in normal range

• Monitor levels of K & Mg during hospitalization

• ↓K or ↓Mg may occur with administration of potassium-depleting diuretics, increasing the potential for Torsades de Pointes

Pharmacokinetics• Half life is ~ 10 hours – therefore usually

ordered twice daily & administered every 12 hrs• Majority (80%) is eliminated via kidneys –

therefore dosing must be adjusted based on calculated creatinine clearance

• Relationship between plasma levels & change from baseline in QTc is predictable & linear

Why Do Patients Need Admitted

• The dose must be individualized for the patient’s renal function & QTc response

• Monitor for side effects of the drug including serious ventricular arrhythmias

Side Effects• Most Common:

– Headache, chest pain, and dizziness

• Others:

– Allergic reaction

– Lightheaded or fainting

– Bradycardia and AV blocks

– Fast heartbeats including Torsades de Pointes

– Severe diarrhea

– Unusual sweating

– Vomiting

– Less appetite than normal

– More thirst than normal

Who Can Order Tikosyn

• Only physicians that have completed the Tikosyn education

• Pharmacy has a list of prescribers authorized to administer / order the medication

Admission Day – Day One

• PRESCRIBER to write initial order for Tikosyn and dosage adjustment (if warranted per treatment algorithm)

• NURSE places patient on telemetry and obtains baseline 12-lead EKG with QT or QTc interval and document on Tikosyn Worksheet

• NURSE places “Dofetilide (Tikosyn) New Start Protocol – Nursing” worksheet in patient’s chart and scans into Pyxis-Connect after each QT or QTc measurement

• PHARMACIST completes “Dofetilide (Tikosyn) New Start Protocol – Pharmacy” worksheet Day #1. Current medication list must be entered into system prior to dispensing drug

Tikosyn Worksheet

RN Responsibility Prior to First Dose

• Obtain 12-lead EKG– Can use “unconfirmed” 12-lead EKG QT

or QTc measurement

• Document initial baseline QTc – If HR < 60 use QT instead of QTc– If > 440 msec* (or > 500 msec* for patients

w/ ventricular conduction abnormalities) the patient is NOT a candidate for this therapy

• Calculate the “threshold QTc”– Initial baseline QTc x 1.15 – Use this value only to assess FIRST dose

given* NOTE: 0.1 sec = 100 msec

RN Responsibility for Following Doses

• Obtain 12-lead EKG 2 to 3 hrs after EACH dose

• Document QTc – Use QT interval if HR < 60

• Notify the physician & pharmacy:– If QTc > “Threshold QTc determined” OR– If QT or QTc is > 500 msec OR– If QT or QTc is > 550 msec for patients

with ventricular conduction abnormalities– If above criteria met, the dose will

either be decreased or discontinued

Day 2• NURSE monitors patient response using QT

or QTc interval measured from a 12-lead EKG 2 to 3 hours after each dose – Document on nursing worksheet & scan to

pharmacy– Contact physician to D/C if QT or QTc interval

> maximum interval for that dose• PHARMACIST evaluates each QT or QTc

interval to determine if patient appropriate for additional doses. If dose is appropriate, next dose will be sent. If not appropriate, pharmacy will contact physician for next dose if nurse has not yet reached the physician

• PHARMACIST counsels patient on proper use & gives patient a Tikosyn Resource Kit. Documents education on the patient education checklist

Day 3

• PRESCRIBER to write prescription on order sheet for 7-day outpatient Tikosyn supply

• PHARMACIST to dispense 7-day outpatient Tikosyn supply

• NURSE to obtain the outpatient Tikosyn prescription from pharmacy. Patient must be discharge with 7-day supply of medication

Pts Admitted Already On Tikosyn• PRESCRIBER to write order for

maintenance per outpatient dosing. Consider telemetry monitoring if patient has acute renal dysfunction.

• PHARMACIST to complete Dofetilide (Tikosyn) Protocol – Pharmacy (Maintenance) worksheet. Current Medication List must be entered into system prior to dispensing drug.

Patient Teaching• Patient resource kit• Pharmacy will educate patients

– What to do for a missed dose– What other drugs are contraindicated– Patients need to notify other physicians

and pharmacies of Tikosyn use

Patient Checklist• Take Tikosyn each day as prescribed

• Tell your MD & Pharmacist the names of ALL medications you are taking

• Call your MD right away if:– Feel faint– Become dizzy– Have a fast heartbeat

• Possible side effects are:– Abnormal heartbeat – Headache, chest pain, dizziness

Measuring QT and QTc• Cardiology stated we can use the

“unconfirmed” QT or QTc from the 12-lead EKG

• If you want to know how this number is determined: – QT: Measurement from beginning of Q

wave through completion of T wave– If HR > than 60 use QTc (corrected QT) –

not necessary to calculate if using number from the 12-lead EKG

• QTc = QT divided by square root of the RR interval in seconds

• The RR interval is obtained by measuring the time elapsed between two consecutive R waves

QTc = QT / square root RR interval in seconds

• QTc = 0.32 / square root 0.44

• QTc = 0.32 / 0.66• QTc = 0.48 sec or

480 msec

• QTc = 0.40 / square root 1.16• QTc = 0.40 / 1.07• QTc = 0.37 sec or 370 msec

Questions???• Jennifer Blake - 4783• Vicki Lindgren – 4961• Or any pharmacist