IN PATIENTS WITH SUBCLINICAL HYPOTHYROIDISM WHILE IN THERAPY WITH TABLET L-T4, THE LIQUID L-T4 FORMULATION IS MORE...

Levothyroxine (L-T4) is the standard therapy of hypothyroidism. Our purpose was to compare the effectiveness of the L-T4 liquid formulation with respect to L-T4 tablet in hypothyroid patients without malabsorption or drug interference. Twenty-one subjects with high thyroid-stimulating hormone (TSH) values under therapy with L-T4 tablets were switched to liquid L-T4 at the same dosage given 30 minutes before breakfast.

TSH values significantly declined 2 months after from the switch to liquid L-T4, reaching the normal range in most cases. In 15 (of the 21 patients) who switched back to tablets, TSH increased again to the hypothyroid range. Since the liquid L-T4 formulation resulted in better TSH level control, all patients were finally treated with the liquid L-T4, and TSH, free tri-iodothyronine and free thyroxine were evaluated again after 6 and 12 months, resulting in normal ranges in all subjects.

The change from tablets to liquid oral formulation normalized serum TSH levels, while switching back to tablets caused thyrotropin levels to worsen. These results suggest that the liquid L-T4 formulation is more effective than tablets in controlling TSH levels in hypothyroid patients in the absence of malabsorption, gastric disorders, or drug interference.

BMI = body mass index FT3 = free tri-iodothyronine FT4 = free thyroxine L-T4 = levothyroxine PPIs = proton-pump inhibitors TSH = thyroid-stimulating hormone.