Levothyroxine is a hormone used to replace the hormone that is normally produced by your thyroid gland. This hormone is responsible for regulating the body's energy and metabolism. Levothyroxine is given when the thyroid gland does not produce enough of this hormone on its own hence, it is used to treat hypothyroidism. Levothyroxine is likewise indicated in the treatment or prevention of enlarged thyroid gland (goiter), which can be caused by hormone imbalances, radiation treatment, surgery, or cancer. Levothyroxine should not be prescribed to treat obesity.
Do not use levothyroxine if you have had a heart attack, a thyroid disorder called thyrotoxicosis, or an adrenal gland problem. Prior to intake of this medication, inform your doctor if you have heart disease, coronary artery disease, anemia, diabetes, pituitary or adrenal gland problems, or a history of blood clots. If you using insulin or taking oral anti-diabetes agents, ask your doctor if your dose needs to be changed when you start using levothyroxine.
Levothyroxine is safe to use while you are pregnant and while you are breast-feeding. This drug does pass into breast milk, but does not harm a nursing baby. If you become pregnant during treatment or if you breast-fed, an increase dose of this drug may be prescribed for you. Long term treatment with levothyroxine may cause bone loss, which can lead to osteoporosis. Discuss with your doctor this potential complication of prolonged treatment.
Take levothyroxine exactly as prescribed for you and not more than that is recommended to avoid serious side effects. It is very important to take levothyroxine with a full glass of water and on an empty stomach or at least 30 minutes before eating. The levothyroxine tablet can dissolve very quickly and swell in the throat, possibly causing choking. It is usually taken in the morning. Try to take this hormone at the same time daily. It may take several weeks before you see its maximum beneficial effects so do not stop taking this medication suddenly. As a replacement therapy, even if you feel well, you may still need to take this medicine every day for the rest of your life. Kidney or liver function tests may be requested to adequately monitor the progress to treatment. It is not advisable to take a double dose to make up the missed dose. Be aware of the different brands of levothyroxine because it may not work the same.
Symptoms of a levothyroxine overdose may include chest pain, pounding heartbeat, shortness of breath, tremor, shortness of breath, leg cramps, confusion, vomiting, diarrhea, or seizures. Seek emergency medical help if any suspected overdose symptoms are experienced. Avoid the following food products: infant soy formula, cotton seed meal, walnuts, and high-fiber foods. These food products can decrease the absorption of levothyroxine in the body.
Discontinue levothyroxine and get emergency medical attention if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Also inform your doctor once you developed any of these serious side effects: headache; sleep problems; nervous or irritable feeling; fever, hot flashes, sweating; menstrual period changes; appetite and weight changes. Mild hair loss is a minor side effect. For any other unusual side effects not listed here, inform your doctor.
The following drugs may cause medical problems if you use them with levothyroxine: lithium, amiodarone, antidepressants or if you recently received radiation therapy with radioactive iodine 131. Some medicines can be continued, but they may make levothyroxine less effective if taken at the same time. If you use any of the following drugs, use them at least 4 hours before or 4 hours after you take levothyroxine: calcium carbonate (Caltrate, Citracal, Oystercal, and others); ferrous sulfate iron supplement; sucralfate (Carafate); sodium polystyrene sulfonate (Kayexalate, Kionex); antacids that contain aluminum (Amphojel, Gaviscon, Maalox, Mylanta, Riopan, Rulox, Tums); and cholesterol-lowering drugs cholestyramine (Questran) and colestipol (Colestid). There are many other drugs not mentioned above that can interact with levothyroxine. Always inform your doctor about all the prescription and over-the-counter medications you use including vitamins, minerals, herbal products, and drugs prescribed by other doctors.
Levothyroxine (T4) Sodium has an empirical formula of C15H10I4NNaO4xH2O, and molecular weight of 798.86 (anhydrous). Synthroid Tablets Inactive Ingredients: Acacia, confectioner's sugar (contains cornstarch), lactose, magnesium stearate, povidone, and talc. The following are the color additives by tablet strength: 25 mcg: FD&C yellow No. 6; 50 mcg: None; 75 mcg: FD&C red No. 40, FD&C blue No. 2; 88 mcg: FD&C blue No. 1, FD&C yellow No. 6, D&C yellow No. 10; 100 mcg: D&C yellow No.10, FD&C yellow No. 6; 112 mcg: D&C red No. 27 & 30; 125 mcg: FD&C yellow No. 6, FD&C red No. 40, FD&C blue No. 1; 150 mcg: FD&C blue No. 2; 175 mcg: FD&C blue No. 1, D&C red No. 27 & 30; 200 mcg: FD&C red No. 40; 300 mcg: D&C yellow No. 10, FD&C yellow No. 6, FD&C blue No. 1. Synthroid Injection Inactive Ingredients: 10 mg mannitol, USP, sodium hydroxide, 0.7 mg tribasic sodium phosphate, anhydrous dodecahydrate. Levothyroxine sodium powder for reconstitution for injection is a sterile preparation.
Levothyroxine has the following structural formula: