PSAT366 Liquid L-thyroxine (L-T4) Formulation Normalizes TSH in Hypothyroid Patients Treated with Tablets L-T4 Open Access

The absorption of L-thyroxine (L-T4) can be affected by different factors, such as the manner of L-T4 assumption (during breakfast, or with food), the age of the patient, the interference with other drugs, absorption kinetics, adherence to therapy, and others. L-T4 tablets malabsorption can occur due to the increased gastric pH in patients in treatment with proton pump inhibitors (PPI; omeprazole, pantoprazole, lansoprazole) for gastritis, gastric ulcer, etc.

We enrolled 25 patients in treatment with L-T4 in the tablet formulation, and with elevated serum thyroid-stimulating hormone (TSH) levels; they were switched to the same dose of an oral liquid L-T4 preparation.

A normalization, or reduction, of circulating TSH levels occurred after the switch from L-T4 in tablet formulation to the liquid one (at the same dose). Eleven of these subjects who, for different reasons, were switched back again to assume L-T4 in tablets (with the same dosage), had a worsening of TSH levels, reaching the hypothyroid range.

Our results show that the pH alteration issue due to PPI could be overcome by the assumption of the oral L-T4 liquid formulation. Other future studies are needed to investigate liquid L-T4 formulation also in other conditions of altered L-T4 absorption.

Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.