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| Clinical data | |
|---|---|
| Trade names | Synthroid, Levoxyl, Thyrax, others |
| Other names | 3,5,3′,5′-Tetraiodo-L-thyronine |
| AHFS/ Drugs.com | Monograph |
| MedlinePlus | a682461 |
| License data |
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Pregnancy category |
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Routes of administration | By mouth, intravenous |
| Legal status | |
| Legal status |
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| Pharmacokinetic data | |
| Bioavailability | 40-80% [2] |
| Metabolism | mainly in liver, kidneys, brain and muscles |
| Elimination half-life | ca. 7 days (in hyperthyroidism 3–4 days, in hypothyroidism 9–10 days) |
| Excretion | feces and urine |
| Identifiers | |
| |
| Chemical and physical data | |
| Formula | C15H11I4NO4 |
| Molar mass | 776.874 g·mol−1 |
| 3D model ( JSmol) | |
| Melting point | 231 to 233 °C (448 to 451 °F) [3] |
| Solubility in water | Slightly soluble (0.105 mg·mL−1 at 25 °C) [4] mg/mL (20 °C) |
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Levothyroxine, also known as L-thyroxine, is a manufactured form of the thyroid hormone thyroxine (T4). [2] [6] It is used to treat thyroid hormone deficiency, including the severe form known as myxedema coma. [2] It may also be used to treat and prevent certain types of thyroid tumors. [2] It is not indicated for weight loss. [2] Levothyroxine is taken by mouth or given by injection into a vein. [2] Maximum effect from a specific dose can take up to six weeks to occur. [2]
Side effects from excessive doses include weight loss, trouble tolerating heat, sweating, anxiety, trouble sleeping, tremor, and fast heart rate. [2] Use is not recommended in people who have had a recent heart attack. [2] Use during pregnancy has been found to be safe. [2] It is recommended that dosing be based on regular measurements of thyroid-stimulating hormone (TSH) and T4 levels in the blood. [2] Much of the effect of levothyroxine is following its conversion to triiodothyronine (T3). [2]
Levothyroxine was first made in 1927. [6] It is on the World Health Organization's List of Essential Medicines. [7] Levothyroxine is available as a generic medication. [2] The wholesale cost in the developing world is about US$0.58 to US$12.28 per month. [8] In the United States, a typical month of treatment costs less than US$25. [9] Levothyroxine was the third most commonly prescribed medication in the United States in 2017, with more than 101 million prescriptions. [10] [11]
References
- ^ a b "Levothyroxine Use During Pregnancy". Drugs.com. 31 July 2019. Archived from the original on 3 August 2020. Retrieved 22 February 2020.
- ^ a b c d e f g h i j k l m n o "Levothyroxine Sodium". The American Society of Health-System Pharmacists. Archived from the original on 21 December 2016. Retrieved 8 December 2016.
- ^ Harington CR (1926). "Chemistry of Thyroxine: Constitution and Synthesis of Desiodo-Thyroxine". The Biochemical Journal. 20 (2): 300–13. doi: 10.1042/bj0200300. PMC 1251714. PMID 16743659.
- ^ DrugBank DB00451
- ^ "WHOCC - ATC/DDD Index". www.whocc.no. Archived from the original on 3 August 2020. Retrieved 18 September 2020.
- ^ a b King, Tekoa L.; Brucker, Mary C. (2010). Pharmacology for Women's Health. Jones & Bartlett Publishers. p. 544. ISBN 9781449658007. Archived from the original on 10 September 2017.
- ^ World Health Organization (2019). World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization. hdl: 10665/325771. WHO/MVP/EMP/IAU/2019.06. License: CC BY-NC-SA 3.0 IGO.
- ^ "Levothyroxine". International Drug Price Indicator Guide. Archived from the original on 22 January 2018. Retrieved 8 December 2016.
- ^ Hamilton, Richart (2015). Tarascon Pocket Pharmacopoeia 2015 Deluxe Lab-Coat Edition. Jones & Bartlett Learning. p. 223. ISBN 9781284057560.
- ^ "The Top 300 of 2020". ClinCalc. Archived from the original on 12 February 2021. Retrieved 27 February 2020.
- ^ "Levothyroxine - Drug Usage Statistics". ClinCalc. 23 December 2019. Archived from the original on 3 August 2020. Retrieved 7 April 2020.