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Flecainide


Serum
Test performed by: LabPLUS High Performance Liquid Chromatography


Specimen Collection

Tubes containing gel (SST and PST) are NOT acceptable


Plain

0.5 mL Paediatric Plain Blood (Preferred)

Plain

4 mL Plain Blood (Preferred)

Heparin

4 mL Heparin Blood
Reference Intervals

For patients on slow-release flecainide blood may be taken at any time. For short-acting flecainide blood should be taken at least 8h post-dose.

Units: ug/L

Therapeutic range : Adult : 260-870

Risk of adverse effects may be higher at trough levels greater than 620 ug/L.

Children (age <18yrs) : 174-435

Flecainide trough concentrations up to 685 ug/L may be required for adequate control in some children.


Uncertainty of Measurement : 10%



Turnaround Time: Between 1 day and 4 days

Test performed 2x per week (usually Mon/Thurs).

If required urgently on weekdays please contact the laboratory.

If required after hours or on weekends, this must be arranged with the laboratory and approval of the Chemical Pathologist may be required.


Assay Method

Principle : High performance liquid chromatography


Diagnostic Use and Interpretation

Monitoring

Flecainide is a local anaesthetic which has a membrane stabilising effect, reducing conduction in all parts of the heart.

Peak levels are reached in about 3 hours (range 1 - 6 hours) with a plasma half life of 12 - 27 hours, reaching steady state in 3 - 5 days.

Periodic drug level monitoring is recommended on patients with renal or hepatic disease, both of which will reduce the elimination rate and could lead to toxic levels. It is also recommended in patients on concurrent amiodarone therapy.

There have been a few reports of hepatotoxicity .

Note : several case reports reported reduction of Flecainide level after milk intake in infants. Withdrawal of milk intake on weaning can potentially increase Flecainide level while on same dose.



See Hepatoxic Drug Reactions


Contact Information

The chemical pathology team can be reached via email: chemicalpathologist@adhb.govt.nz or via Lablink (09) 307 4949 ext 22000 or 09-3078995

Emails will receive priority attention from the on-call chemical pathologist. Include the patients NHI.

After-hours: contact Lablink (Auckland City Hospital ext. 22000 or 09-3078995) or hospital operator for on duty staff after hours .


For more information, contact the laboratory or Dr. Gerald Woollard ext 22053


Specimen Transport Instructions for Referring Laboratories

Centrifuge and separate blood as soon as possible after collection.

If sending within Auckland then sample can be sent refrigerated (2-8 degrees) or at ambient temperature (8-24 degrees).

If sending from outside Auckland then send sample refrigerated (2-8 degrees).

Note: If temperature during shipping is likely to exceed 24 degrees then results may not always be reliable.



Last updated at 11:42:03 16/01/2026