LevothyroxineLevothyroxine Sodium

About Levothyroxine

Levothyroxine replaces thyroxine (T4), the main hormone the thyroid makes. The tablet labels approve it for primary, secondary or tertiary hypothyroidism, present from birth or acquired, in adults and children including newborns, and with surgery and radioactive iodine to suppress TSH in well-differentiated thyroid cancer that depends on TSH. It is not indicated for shrinking benign nodules or goiter in people with enough iodine, or for hypothyroidism while recovering from subacute thyroiditis. Full replacement in adults is about 1.6 mcg per kg a day, started lower and raised more slowly in older adults and people with heart disease; doses change in 12.5 to 25 mcg steps every 4 to 6 weeks, with a TSH check 6 to 8 weeks after any dose change and every 6 to 12 months once stable.

The boxed warning says thyroid hormones must not be used to treat obesity or for weight loss: usual doses do not reduce weight in people with normal thyroid function, and larger doses can cause serious or life-threatening toxicity, especially with stimulant appetite suppressants. Levothyroxine must not be started with uncorrected adrenal insufficiency. Too much can cause angina or abnormal heart rhythms, especially in older adults and people with heart disease, and over-replacement can reduce bone density. It can worsen blood sugar control in diabetes, and forms taken by mouth are not recommended for myxedema coma. Side effects are mainly those of too much hormone, such as palpitations, a fast heartbeat, nervousness, tremor, trouble sleeping, heat intolerance and weight loss.

Tirosint, a soft gel capsule, is labeled for adults and children 6 and older who can swallow it whole. The label says levothyroxine has a narrow therapeutic index. In the Orange Book, tablets carry numbered equivalence codes (AB1 to AB4) tied to particular reference products, some carry more than one, and a tablet is equivalent only to products sharing one of its codes. The labels set no rule on switching products: MedlinePlus advises against switching brands without first asking the doctor or pharmacist, and an FDA page reports a study finding no significant change in TSH when patients switched between generic makers. Pregnancy can raise the dose needed, so the label calls for TSH and free T4 checks as soon as pregnancy is confirmed and at least once each trimester.

Taking Levothyroxine

How to take it

Once a day on an empty stomach, 30 to 60 minutes before breakfast (Tirosint-SOL 15 minutes before), at least 4 hours apart from medicines that block its absorption. Swallow tablets with a full glass of water, since they can stick in the throat, swallow capsules whole, and measure Thyquidity with an oral syringe. For an infant, crush a tablet into 5 to 10 mL of water and give it at once, never in soy formula.

If you miss a dose

Take it as soon as you remember, unless it is almost time for the next dose; then skip the missed dose. Do not take a double dose.

Storage

At room temperature, protected from light and moisture, out of reach of children. Keep Tirosint capsules in the blister until you take them, and use a Thyquidity bottle within 8 weeks of opening.

Interactions to know about

Take calcium carbonate, iron and phosphate binders such as sevelamer at least 4 hours apart, and bile acid binders at least 4 hours after it; proton pump inhibitors, antacids, sucralfate, orlistat, soybean flour, walnuts, fiber and grapefruit juice can reduce or delay absorption. It strengthens warfarin and can change digoxin and diabetes medicine needs. Biotin skews thyroid blood tests, so stop it at least 2 days before one.

This summarizes the official prescribing information. Your prescriber’s and pharmacist’s instructions, and the leaflet that comes with your medicine, take priority.

Why the cash price for Levothyroxine differs from pharmacy to pharmacy

Generic levothyroxine tablets come from several makers alongside the Synthroid, Levoxyl and Unithroid brands. A pharmacist can substitute only a tablet that shares an equivalence code with the product prescribed, and a prescription that names a brand and blocks substitution is priced as a brand.

Tirosint capsules and the two solutions have no generic listed as marketed and are priced as brands, and none can be swapped at the counter for tablets or for each other.

Ways to pay less for Levothyroxine without insurance

• Ask for a rated generic, and ask which maker’s tablets each quote is for, so you can stay on the same one.
• Once your dose is stable, ask for a ninety-day supply.
• If you take Tirosint, Tirosint-SOL or Thyquidity, ask the maker whether a savings or patient assistance program applies to someone paying cash.
• If a capsule or solution was prescribed and you can swallow tablets, ask the prescriber whether tablets would suit you, and whether your TSH should be rechecked after any change of product.
• Upload the prescription to Script Unlock so licensed pharmacies can quote their cash price. You pay the pharmacy directly.

Questions to ask your pharmacist about Levothyroxine

1. 1.Is this the same maker and product as my last fill?
2. 2.How far apart should I take it from my calcium, iron, antacid or cholesterol medicine?
3. 3.When should my TSH be checked after a dose or product change?
4. 4.Should I stop biotin before my thyroid blood test?

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