Synthroid
Synthroid®
(levothyroxine sodium) Tablets, USP
DRUG DESCRIPTION
SYNTHROID® (levothyroxine sodium tablets, USP) contain synthetic crystalline L-3,3',5,5'-tetraiodothyronine sodium salt [levothyroxine (T4) sodium]. Synthetic T4 is identical to that produced in the human thyroid gland. Levothyroxine (T4) sodium has an empirical formula of C15H10I4N NaO4 • H2O, molecular weight of 798.86 g/mol (anhydrous), and structural formula as shown:
 |
Inactive Ingredients: acacia, confectioner's sugar (contains corn starch), lactose monohydrate, magnesium stearate, povidone, and talc. The following are the color additives by tablet strength:
| Strength (mcg) | Color additive(s) |
| 25 | FD&C Yellow No. 6 Aluminum Lake |
| 50 | None |
| 75 | FD&C Red No. 40 Aluminum Lake, FD&C Blue No. 2 Aluminum Lake |
| 88 | FD&C Blue No. 1 Aluminum Lake, FD&C Yellow No. 6 Aluminum Lake, D&C Yellow No. 10 Aluminum Lake |
| 100 | D&C Yellow No. 10 Aluminum Lake, FD&C Yellow No. 6 Aluminum Lake |
| 112 | D&C Red No. 27 & 30 Aluminum Lake |
| 125 | FD&C Yellow No. 6 Aluminum Lake, FD&C Red No. 40 Aluminum Lake, |
| FD&C Blue No. 1 Aluminum Lake | |
| 137 | FD&C Blue No. 1 Aluminum Lake |
| 150 | FD&C Blue No. 2 Aluminum Lake |
| 175 | FD&C Blue No. 1 Aluminum Lake, D&C Red No. 27 & 30 Aluminum Lake |
| 200 | FD&C Red No. 40 Aluminum Lake |
| 300 | D&C Yellow No. 10 Aluminum Lake, FD&C Yellow No. 6 Aluminum Lake, FD&C Blue No. 1 Aluminum Lake |
Meets USP Dissolution Test 3
What are the possible side effects of levothyroxine (Levothroid, Levoxyl, Synthroid, Tirosint, Unithroid)?
Stop using levothyroxine and get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have any of these serious side effects:
- headache;
- sleep problems (insomnia);
- nervous or irritable feeling;
- fever, hot flashes, sweating;
- changes in your menstrual periods;
- appetite changes, weight changes;
Less serious side effects may include mild hair...
Read All Potential Side Effects and See Pictures of Synthroid »
What are the precautions when taking levothyroxine sodium (Synthroid)?
Before taking levothyroxine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
Before using this medication, tell your doctor or pharmacist your medical history, especially of: increased thyroid hormones (thyrotoxicosis), decreased adrenal gland function, heart disease (such as coronary artery disease, irregular heartbeat), high blood pressure, diabetes.
Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).
Current information shows that this drug may be used during pregnancy....
Last reviewed on RxList: 11/1/2010
This monograph has been modified to include the generic and brand name in many instances.
Additional Synthroid Information
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