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Pharmacy and Medications

Dosage Equivalencies



What is the equivalent dose of dessicated porcine thyroid to replace 100mcg of Levoxyl? The dessicated thyroid comes in milligrams so it appears that the numbers don`t translate directly.


The reason that the numbers do not translate directly is that the desiccated thyroid (ArmourTM Thyroid) product is a natural product derived from porcine thyroid containing both T4 (levothyroxine) and T3 (liothyroxine) in a ratio of 4.22:1. Levoxyl® on the other hand is a synthetic compound containing only levothyroxine (T4).

The general conversion used for switching from Levoxyl® to desiccated thyroid is generally 25mcgs of Levoxyl® for every 15mgs (1/4 grains) of desiccated thyroid. So when switching from 100mg of Levoxyl®, the equivalent dose of desiccated thyroid would be 60mgs (1 grain).1

1. Drug facts and Comparisons:2009 Edition. Wolters Kluwer Health; 2009:486-95

Answer submitted by Charles Skluzacek, Ohio State University-College of Pharmacy, PharmD Candidate, Class of 2011

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Response by:

David Baker, PharmD, DABAT
Formerly, Clinical Assistant Professor of Pharmacy
College of Medicine
The Ohio State University