Names and pronunciation
Tikosyn
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Drug reference
Tikosyn
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Func. class.: Antidysrhythmic (Class III)
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ACTION: Blocks cardiac ion channel carrying the rapid component of delayed potassium current; no effect on sodium channels
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USES: Atrial fibrillation, flutter, main- tenance of normal sinus rhythm
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CONTRAINDICATIONS: Chil- dren, hypersensitivity, digoxin toxicity, aortic stenosis, pulmonary hypertension, severe renal disease, QT prolongation, torsades de pointes, renal failure Precautions: Pregnancy, breastfeeding, AV block, bradycardia, electrolyte imbal- ance, renal disease
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Black Box Warning: Arrhythmias, ven- tricular arrhythmias/tachycardia; requires an experienced clinician in specialized care setting Black Box Warning: Step 1: Assess cardiac conduction: Prior to first dose, the QTc interval must be determined us- ing an average of 5-10 beats; if the QTc interval is >440 msec (or >500 msec in ventricular conduction abnormalities), do not use; if baseline heart rate is <60 BPM, then the QT interval should be used Black Box Warning: Step 2: Assess renal function: Prior to first dose, deter- mine renal function using the Cockcroft- Gault equation, use actual body weight to calculate creatinine clearance Black Box Warning: Step 3: Adjust start- ing dose according to renal function: Refer to the renal dose section above to determine the appropriate initial dosage Black Box Warning: Step 4: ECG moni- toring: Begin continuous ECG monitoring D starting with the first dose Black Box Warning: Step 5: Dosage ad- justments: Approximately 2-3 hr after the first dose, determine the QTc interval; if the QTc interval has increased by >15% (com- pared to baseline), or if the QTc interval is >500 msec (>550 msec in patients with ven- tricular conduction abnormalities), the initial dosage should be reduced by half as follows: • Decrease an initial dose of 500 mcg bid to 250 mcg bid • Decrease an initial dose of 250 mcg bid to 125 mcg bid • Decrease an initial dose of 125 mcg bid to 125 mcg/day Black Box Warning: Step 6: Reassess QTc interval: Reassess the QTc interval 2-3 hr after each subsequent dose; if the QTc interval lengthens to >500 msec (or >550 msec in patients with ventricular conduction abnormalities), discontinue Black Box Warning: Step 7: ECG moni- toring: Monitor continuous ECG for a minimum of 3 days or for 12 hr after con- version to normal sinus rhythm, which- ever is greater Black Box Warning: Dysrhythmias: 3 days of continuous ECG monitoring, mon- itoring of CCr are required when starting or restarting medication; have cardiac resuscitation equipment nearby • Cardiac status: rate, rhythm, charac- ter, continuously; B/P • Severe renal impairment CCr <20 mL/ min: do not use for mild to moderate renal disease; monitor BUN/creatinine; adjust dose based on creatinine clearance • Pregnancy/breastfeeding: no well- controlled studies; use only if benefit outweighs fetal risk; avoid breastfeeding, excretion is unknown
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SIDE EFFECTS CNS: Dizziness, headache, stroke CV: QT prolongation, torsades de pointes, ventricular dysrhythmias, chest pain GI: Nausea, diarrhea
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INTERACTIONS • Do not use with cimetidine, ketocon- azole, verapamil, prochlorperazine, trimeth oprim-sulfamethoxazole, megestrol, hy- droCHLOROthiazide Increase: QT prolongation, torsades de pointes—class IA/III antidysrhythmics, arsenic trioxide, chloroquine, clarithromy- cin, droperidol, erythromycin, halofantrine, haloperidol, methadone, pentamidine, some phenothiazines, ziprasidone, ciprofloxacin Increase: hypokalemia—potassium- depleting diuretics Increase: toxicity—aMILoride metFOR- MIN, entecavir, lamiVUDine, memantine, triamterene, procainamide, trospium Increase: dofetilide levels—antiretrovi- ral protease inhibitors Increase: dysrhythmias—CYP3A4 inhibi- tors (SSRIs, macrolides, azoles, protease inhibitors, amiodarone, diltiazem, quinine) Drug/Food • Do not use with grapefruit juice
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DOSAGE AND ROUTES Adult: PO 500 mcg bid initially; mainte- nance 250 mcg bid, max 500 mcg bid; ad- just dose based on QT and renal function Renal dose • Adult: PO CCr >60 mL/min, 500 mcg bid; CCr 40-60 mL/min, 250 mcg bid; CCr 20-39 mL/min, 125 mcg bid; CCr <20 mL/ min, do not use
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Available forms: Capsules 125, 250, 500 mcg
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Administer: • Physician and pharmacy must be reg- istered to use product • With patient hospitalized for ≥3 days
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Assess: • AF patients should receive anticoagu- lation prior to cardioversion
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Evaluate: • Therapeutic response: control of atrial fibrillation, normal sinus rhythm
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • To make position changes slowly; or- thostatic hypotension may occur • To notify prescriber if fast heartbeats with fainting or dizziness occur • To notify all prescribers of all medica- tions, supplements taken • That if dose is missed, not to double; to take next dose at usual time • To avoid breastfeeding
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PHARMACOKINETICS Well absorbed, max plasma concentra- tions 2-3 hr, steady state 2-3 days, half-life 10 hr, metabolized by liver, excreted by kidneys, peak 3 hr, duration up to 24 hr
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• Adult: PO CCr >60 mL/min, 500 mcg bid; CCr 40-60 mL/min, 250 mcg bid; CCr 20-39 mL/min, 125 mcg bid; CCr <20 mL/ min, do not use
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