Tuesday, December 4, 2018

Dig and OTC compounds

Q: 53-year-old male with a history of ischemic cardiomyopathy presented to ED with dizziness. EKG was found to have a third degree AV block. Laboratory work showed Digoxin level of 5.4 ng/mL. Patient reports not to change the doses of any of his medications, albeit he stops taking a lot of over the counter self-help herbal remedies in last one month. Withdrawal of which of the following compounds may increase the chances of "Dig. Toxicity"?

A) Garlic 
B) Saw palmetto 
C) St. John's Wort 
D)  Bilberry
E) Aloe

Answer: C

Taking Digoxin with St. John's Wort decreases its effect via decrease absorption. St. John's wort contains hypericum which induces intestinal P-glycoprotein/Multiple Drug Resistance (MDR)-1 drug transporters gene.

Clinicians without the knowledge of the patient's over the counter intake of supplements may increase the dose to obtain a clinically therapeutic effect. Subsequently, if this balance disrupted, may cause a sudden rise in serum digoxin level.



Johnte A et al. Pharmacokinetic interaction of digoxin with an herbal extract from St John's wort (hypericum perforatum). Clin Pharmacol Ther 1999 Oct 66 338345

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