Digibind Dosing

[Praziquantel86]

A case came up recently, and I was wondering if the toxicology types here might have any input to an interesting dilemma.

Basically, should Digibind be redosed in acutely dig-toxic patients with severe hemodynamic instability on CVVH, and if so, when? Based on the literature I've read, the fab-digoxin complex has a half life of anywhere from 12 to 130 hours in renal failure, with the potential for recurrent toxicity following the dissolution of the immune complex. Patient's in ARF clearly cannot clear either the drug or the complex, so it seems like it's only a matter of time before you'd have to re-dose the Digibind. MARS might be an option based on one case report, but not too many institutions have that capacity yet.

Any clinical experience or literature you might have would be extremely helpful.

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[BADMD]

A case came up recently, and I was wondering if the toxicology types here might have any input to an interesting dilemma.

Basically, should Digibind be redosed in acutely dig-toxic patients with severe hemodynamic instability on CVVH, and if so, when? Based on the literature I've read, the fab-digoxin complex has a half life of anywhere from 12 to 130 hours in renal failure, with the potential for recurrent toxicity following the dissolution of the immune complex. Patient's in ARF clearly cannot clear either the drug or the complex, so it seems like it's only a matter of time before you'd have to re-dose the Digibind. MARS might be an option based on one case report, but not too many institutions have that capacity yet.

Any clinical experience or literature you might have would be extremely helpful.

I haven't had to redose digfab due to renal failure more than a handful of times. Most patients whose toxicity is due to ARF recover some/all of their function when the cause is addressed. While I'm on the lookout for recurrence with the ESRDers, I still haven't had to redose very often.

 

[Praziquantel86]

I haven't had to redose digfab due to renal failure more than a handful of times. Most patients whose toxicity is due to ARF recover some/all of their function when the cause is addressed. While I'm on the lookout for recurrence with the ESRDers, I still haven't had to redose very often.

That's reasonable. I think the ESRD population might be a bit more problematic, though.

So the other question is, what parameters do you use to redose? Dig levels are useless once Digibind has been used and unless you have access to free levels in-house (most are sendouts, I'd guess), there's not much to go.

The parameters I set are generally EKG changes or significant drops in heart rate, but I'd be interested to see what others are doing with this as well.

 

[BADMD]

Free levels aren't that hard, the lab just has to know what they are doing. It can be done relatively easily with a microdialysis tube followed by the standard assay.

As for parameters for redosing, I'm going based on rhythm, rate and electrolytes. It will also depend on how much dig FAB the person was given initially, the initial level, and how low I think we made it with the FAB. The amount of excess FAB given will also be a consideration.