Are liquid levothyroxine formulations comparable? The LETI study
Abstract Background Liquid ethanol-containing levothyroxine (e-LT4) is known to circumvent malabsorption induced by food, drugs, or pathological conditions. Recently a new ethanol-free formulation of liquid levothyroxine (ef-LT4) has been commercialized. No studies have compared e-LT4 with ef-LT4. T...
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BMC
2025-04-01
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| Series: | Thyroid Research |
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| Online Access: | https://doi.org/10.1186/s13044-025-00236-9 |
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| author | Elisa Gatta Virginia Maltese Ilenia Pirola Elena Gandossi Irene Silvestrini Massimiliano Ugoccioni Riccardo Morandi Claudio Casella Carlo Cappelli |
| author_facet | Elisa Gatta Virginia Maltese Ilenia Pirola Elena Gandossi Irene Silvestrini Massimiliano Ugoccioni Riccardo Morandi Claudio Casella Carlo Cappelli |
| author_sort | Elisa Gatta |
| collection | DOAJ |
| description | Abstract Background Liquid ethanol-containing levothyroxine (e-LT4) is known to circumvent malabsorption induced by food, drugs, or pathological conditions. Recently a new ethanol-free formulation of liquid levothyroxine (ef-LT4) has been commercialized. No studies have compared e-LT4 with ef-LT4. The aim of the present study is to compare thyroid hormone profile in patients treated with e-LT4 and ef-LT4. Material and methods We retrospectively retrieved thyroid hormonal profile and clinical data of 48 patients diagnosed with hypothyroidism who had been on stable treatment with an e- LT4 formulation at the same dosage for at least one year and who decided to switch to ef-LT4 for tasting issue. Results A significant increase in TSH levels was observed after 6 months on ef-LT4 treatment (2.5 ± 0.8 mIU/ml vs. 3.1 ± 1.0 mIU/ml, respectively, p < .001), while fT4 decreased [1.2 ng/dl (IQR 1.1–1.4) vs. 1.1 ng/dl (1.0–1.2), respectively, p = .047], maintaining the same dosage of LT4. In 31 patients, for whom data were available 12 months after the switch, TSH further increased (2.50 ± 0.9 mIU/ml at baseline vs 3.2 ± 0.9 mIU/ml after 6 months vs 3.5 ± 0.9 mIU/ml at 12 months, p < .001) and fT4 decreased [1.2 ng/dl (IQR 1.1–1.4) vs. 1.1 ng/dl (IQR 0.9–1.3) vs 1.0 ng/dl (IQR 0.9–1.1), p = .008]. Conclusion ef-LT4 formulation seems to be less effective compared to e-LT4 over time. However, further prospective cross-sectional studies, performed in large sets of patients, even on concomitant therapy with interfering drugs, are needed. |
| format | Article |
| id | doaj-art-b86d2915cd3a4bdd98651f414d4d285a |
| institution | OA Journals |
| issn | 1756-6614 |
| language | English |
| publishDate | 2025-04-01 |
| publisher | BMC |
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| series | Thyroid Research |
| spelling | doaj-art-b86d2915cd3a4bdd98651f414d4d285a2025-08-20T02:20:06ZengBMCThyroid Research1756-66142025-04-011811710.1186/s13044-025-00236-9Are liquid levothyroxine formulations comparable? The LETI studyElisa Gatta0Virginia Maltese1Ilenia Pirola2Elena Gandossi3Irene Silvestrini4Massimiliano Ugoccioni5Riccardo Morandi6Claudio Casella7Carlo Cappelli8Department of Clinical and Experimental Sciences, Endocrine and Metabolic Unit, SSD Endocrinologia, University of Brescia, ASST Spedali CiviliDepartment of Clinical and Experimental Sciences, Endocrine and Metabolic Unit, SSD Endocrinologia, University of Brescia, ASST Spedali CiviliDepartment of Clinical and Experimental Sciences, Endocrine and Metabolic Unit, SSD Endocrinologia, University of Brescia, ASST Spedali CiviliDepartment of Clinical and Experimental Sciences, Endocrine and Metabolic Unit, SSD Endocrinologia, University of Brescia, ASST Spedali CiviliDepartment of Internal Medicine and Therapeutics, University of PaviaDepartment of Internal Medicine and Therapeutics, University of PaviaCentro Per La Diagnosi E Cura Delle Neoplasie Endocrine E Delle Malattie Della Tiroide, University of BresciaCentro Per La Diagnosi E Cura Delle Neoplasie Endocrine E Delle Malattie Della Tiroide, University of BresciaDepartment of Clinical and Experimental Sciences, Endocrine and Metabolic Unit, SSD Endocrinologia, University of Brescia, ASST Spedali CiviliAbstract Background Liquid ethanol-containing levothyroxine (e-LT4) is known to circumvent malabsorption induced by food, drugs, or pathological conditions. Recently a new ethanol-free formulation of liquid levothyroxine (ef-LT4) has been commercialized. No studies have compared e-LT4 with ef-LT4. The aim of the present study is to compare thyroid hormone profile in patients treated with e-LT4 and ef-LT4. Material and methods We retrospectively retrieved thyroid hormonal profile and clinical data of 48 patients diagnosed with hypothyroidism who had been on stable treatment with an e- LT4 formulation at the same dosage for at least one year and who decided to switch to ef-LT4 for tasting issue. Results A significant increase in TSH levels was observed after 6 months on ef-LT4 treatment (2.5 ± 0.8 mIU/ml vs. 3.1 ± 1.0 mIU/ml, respectively, p < .001), while fT4 decreased [1.2 ng/dl (IQR 1.1–1.4) vs. 1.1 ng/dl (1.0–1.2), respectively, p = .047], maintaining the same dosage of LT4. In 31 patients, for whom data were available 12 months after the switch, TSH further increased (2.50 ± 0.9 mIU/ml at baseline vs 3.2 ± 0.9 mIU/ml after 6 months vs 3.5 ± 0.9 mIU/ml at 12 months, p < .001) and fT4 decreased [1.2 ng/dl (IQR 1.1–1.4) vs. 1.1 ng/dl (IQR 0.9–1.3) vs 1.0 ng/dl (IQR 0.9–1.1), p = .008]. Conclusion ef-LT4 formulation seems to be less effective compared to e-LT4 over time. However, further prospective cross-sectional studies, performed in large sets of patients, even on concomitant therapy with interfering drugs, are needed.https://doi.org/10.1186/s13044-025-00236-9Liquid levothyroxineHypothyroidismEthanolLevothyroxine |
| spellingShingle | Elisa Gatta Virginia Maltese Ilenia Pirola Elena Gandossi Irene Silvestrini Massimiliano Ugoccioni Riccardo Morandi Claudio Casella Carlo Cappelli Are liquid levothyroxine formulations comparable? The LETI study Thyroid Research Liquid levothyroxine Hypothyroidism Ethanol Levothyroxine |
| title | Are liquid levothyroxine formulations comparable? The LETI study |
| title_full | Are liquid levothyroxine formulations comparable? The LETI study |
| title_fullStr | Are liquid levothyroxine formulations comparable? The LETI study |
| title_full_unstemmed | Are liquid levothyroxine formulations comparable? The LETI study |
| title_short | Are liquid levothyroxine formulations comparable? The LETI study |
| title_sort | are liquid levothyroxine formulations comparable the leti study |
| topic | Liquid levothyroxine Hypothyroidism Ethanol Levothyroxine |
| url | https://doi.org/10.1186/s13044-025-00236-9 |
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