RF23 | PSAT365 An Open-Label Therapeutic Efficacy Study of Tirosint (Levothyroxine Sodium) Capsules in Thyroidectomized Patients Taking Proton Pump Inhibitors

Levothyroxine sodium (LT4) absorption is known to be affected by proton pump inhibitors (PPIs). Normal gastric acid secretion is important for the subsequent intestinal absorption of LT4. A reduced gastric acidity may diminish the dissolution of the LT4 tablet in the stomach and the release of LT4 to the gut. The dissolution profile of LT4 soft capsules has been reported to be less affected by pH than that of tablets. Previous studies in healthy subjects administered with LT4 and PPIs, as well as in hypothyroid patients with atrophic gastritis confirmed little or no impact of increased gastric pH on LT4 absorption when administered in soft capsule formulation. The present study was aimed at evaluating whether LT4 soft capsules may provide better control of thyroid stimulating hormone (TSH) in thyroidectomized patients undergoing chronic replacement therapy with LT4, who were also on chronic use of PPIs.Forty-seven (47) patients were enrolled in this multicenter study. Upon switching to Tirosint capsules at the same previous dose of LT4 tablets and while maintaining the same dose of PPI, TSH (when measured on week 12 of treatment) was significantly reduced from a mean±SD of 1.34±1.51 mIU/L to 0.75±1.08 mIU/L (p<0.0001) in the Intention-To-Treat population analysis on original data. No significant changes were detected in the level of free and total thyroxine (T4), while slight but significant (p<0.05) increases were measured in free and total triiodothyronine (T3). The measured extent of TSH decrease is consonant with the extent of TSH increase previously reported by other authors upon start of PPI therapy in hypothyroid patients treated with LT4 tablets.In conclusion, these data confirm previous reports that LT4 soft capsules absorption is not affected by increased gastric pH due to PPIs. This may be relevant to improve TSH stabilization in patients who take PPIs intermittently or those with gastric pH altered by concomitant pathologies. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Sunday, June 12, 2022 1:00 p.m. - 1:05 p.m.