Treatment pattern and frequency of serum TSH measurement in users of different levothyroxine formulations: a population-based study during the years 2009–2015

Rosarita Ferrara, Valentina Ientile, Vincenzo Arcoraci, Carmen Ferrajolo, Carlo Piccinni, Andrea Fontana, Salvatore Benvenga, Gianluca Trifirò

Research output: Contribution to journalArticle

Abstract

Background: Several conditions can modify the intestinal absorption of levothyroxine tablets, with potential consequences on their therapeutic effect. Pre-dosed ampoules and oral drops have been recently made available to overcome this limitation. Aims: To describe the pattern of use of different formulations of levothyroxine in a general population of Southern Italy and to perform an exploratory analysis investigating the effect of switching from levothyroxine tablets to oral liquid formulations. Methods: Data were extracted from the Caserta Local Health Unit database. All patients receiving at least one levothyroxine prescription during the years 2009–2015 were identified. 1-year incidence of use of formulation-specific levothyroxine was calculated. Switchers between levothyroxine tablets and oral liquid formulations were identified and the frequency of thyroid-stimulating hormone measurement within 2 years prior and after the switch date was explored. Results: Overall, 56,354 levothyroxine users were included in the study. Of these, 55,147 patients received at least one prescription for tablets (97.9%), 1867 pre-dosed ampoules (3.3%) and 1550 oral drops (2.8%). The proportion of levothyroxine users receiving oral liquid formulations slightly increased over time. Patients switching from tablets to oral liquid formulations showed a statistically significant reduction in the number of thyroid-stimulating hormone measurements after switching from tablets, especially in presence of drugs interacting with levothyroxine potentially altering its absorption. Conclusions: Use of levothyroxine oral liquid formulations is increasing over time even though their use is still limited in a general population of Southern Italy. Our exploratory analysis showed that the frequency of thyroid-stimulating hormone measurement was reduced in patients switching from levothyroxine tablet to new formulations.

Original languageEnglish
Pages (from-to)143-152
Number of pages10
JournalEndocrine
Volume58
Issue number1
DOIs
Publication statusPublished - Oct 1 2017

Keywords

  • Absorption
  • Formulations
  • Levothyroxine
  • Switching
  • TSH

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Endocrinology

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