Levothyroxine
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| Image:Levothyroxine-2D-skeletal.png | |
| Levothyroxine
| |
| Systematic (IUPAC) name | |
| 3,5,3',5'-tetraiodo-L-thyronine | |
| Identifiers | |
| CAS number | 51-48-9 |
| ATC code | H03AA01 |
| PubChem | 853 |
| DrugBank | APRD00235 |
| Chemical data | |
| Formula | C15H10I4NNaO4·H2O |
| Mol. weight | 798.86 (anhydrous) |
| Pharmacokinetic data | |
| Bioavailability | ~100% |
| Metabolism | Mainly in liver, kidneys, brain and muscles |
| Half life | ca. 7 days (in hyperthyroidism 3-4 days, in hypothyroidism 9-10 days) |
| Excretion | Through faeces and urine |
| Therapeutic considerations | |
| Pregnancy cat. |
A (FDA) |
| Legal status |
℞ Prescription only |
| Routes | Oral, Intravenous |
Levothyroxine Sodium, also known as L-thyroxine, synthetic T4 or 3,5,3',5'-tetraiodo-L-thyronine, is a synthetic form of thyroxine (thyroid hormone). As the hormone is chemically in the L-form (instead of D, see chirality), it is metabolized more slowly than physiological thyroid hormone, which has a shorter half-life.
The EU has recently standardized the use of the name "levothyroxine" for the drug. Common brand names include "Thyrax", "Euthyrox", "Levaxin" and "Eltroxin" in Europe, and "Levoxyl" and "Synthroid" in the US.
This medicine is a hormone replacement usually given to patients with thyroid problems, specifically, hypothyroidism. It is also given to people who have goiter ( or an enlarged thyroid gland ).
It is recommended that levothyroxine be taken half an hour to an hour before meals to maximize its absorption. It is also recommended that the patient take the tablet with one glass of water to ease swallowing as well as to help the tablet dissolve for absorption.
There are also foods and other substances that can interfere with absorption of thyroxine replacement. Avoid taking calcium and iron supplements within 4 hours of the medication and avoid taking soy products within 3 hours of the medication as these can reduce absorption of the medication.
Synthetic levothyroxine may have adverse side effects like: palpitations, nervousness, headache, difficulty sleeping, insomnia, swelling of the legs and ankles, weight loss and/or increased appetite. Some may be allergic to the medicine. If the patient develops a severe reaction to this drug like difficulty breathing, shortness of breath or swelling of the face and tongue it is imperative that the patient immediately seek medical intervention.
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