Amiodarone + Phenytoin

[trulylovelyperson]

Nightmare combo....can anyone shed light on what happens in hospital when patient balanced on existing meds including phenytoin is prescribed Amiodarone for atrial fibrillation.
How often would blood tests be done and they would specifically be for......?
Is it likely patient is stilll not stable after 2/3 months?
Thanks for any help

[Nik]

The interaction is complicated - amiodarone can increase phenytoin levels and phenytoin can reduce serum amiodarone levels. Given the fact that a pt is stabilised on phenytoin, wouldn't want to mess about with the dose, especially considering non-linear pharmacokinetics as well as the starting regime for amiodarone.

[crit care]

i guess monitor phenytoin levels, and adjust according to albumin. Monitor for AF, ie heart rate and the like. Often its risk vs benefit, risk of phenytoin toxicity against benefits of giving amidoarone to manage AF.

As you are introducing amiodarone to the phenytoin i would probably monitor phenytoin levels, amiodarone takes a while to rech steady state, hence the length laoding dose for it

[Nik]

I would prefer to avoid the hassle but there you go ! Suppose it also depends on the type of AF and if another drug couldn't be considered eg flecainide.

[trulylovelyperson]

Thanks for the replies guys.