PII-087 - THE EFFECT OF FOOD ON T3 AND T4 BIOAVAILABILITY AND THE DOSE PROPORTIONALITY OF ARMOUR THYROID.

B. McNamee¹, R. Boinpally², P. Watson³, C. Min³, E. Kaczynski²; ¹AbbVie Inc., Belfast, United Kingdom, ²AbbVie Inc., Princeton, NJ, USA, ³AbbVie Inc., North Chicago, IL, USA.

Background: Armour® Thyroid (thyroid tablets, USP [AT]) contains powdered porcine thyroid gland. Thyroid glands have a natural combination of the thyroid hormones 3, 5, 3′-triiodothyronine (T3) and thyroxine (T4). AT has been commercially available for several decades and is currently prescribed as a replacement or supplemental therapy in patients with hypothyroidism.
This study evaluated the effect of a high fat meal on the oral bioavailability and assessed dose proportionality with respect to T3 and T4 following single-dose oral administration of AT tablets.

Methods: Part 1 assessed the effect of a high fat meal on the oral bioavailability of T3 and T4 following single-dose oral administration of a 5-grain AT tablet in a 2-regimen, 2-sequence, 2-period crossover design (n=20). Part 2 assessed dose proportionality of 1-, 2-, and 5-grain AT tablets in a parallel design (n=20).
Subjects were healthy male and female volunteers aged 18-51 years.
Pharmacokinetic blood samples to determine total and free T3 and T4 concentrations using validated chemiluminescent methods were collected at predose and up to 240 hours postdose.

Results: Following oral administration of a 5-grain AT tablet with food, total T3 maximum concentration (Cmax) decreased 58% and area under the curve (AUCt) decreased 39% compared to fasted conditions; total T4 Cmax decreased 41% and AUCt decreased 14% with food compared to fasted conditions.
Dose-normalized total and free T3 and T4 Cmax and AUCt values were generally comparable for the 1-, 2-, and 5-grain AT tablets.

Conclusion: There was a significant decrease in T3 and T4 bioavailability when AT tablets were administered with a high fat meal compared to the fasted state.
AT tablets exhibit dose proportionality with respect to total and free T3 and T4 concentrations.