Mom asked
My levothyroxine doesn't look the same as it usually does and obviously has sugar in it. I have been crying easily since taking it. What should I do?
Answer
There are over 10 different generic manufacturers that produce levothyroxine, a thyroid replacement medication. While they will all contain the same amount of the active ingredient, they will vary in their inactive ingredients. This is why the same medication, from different manufacturers, look different.
As an example, below is the ingredient list for two different levothyroxine products.
Mylan Levothyroxine 50mcg
- Butylated Hydroxyanisole
- Crospovidone
- Magnesium Stearate
- Mannitol
- Microcrystalline Cellulose
- Povidone
- Silicon Dioxide (Colloidal)
- Sodium Lauryl Sulfate
- Sucrose
Sandoz Levothyroxine 50mcg
- Magnesium Stearate
- Microcrystalline Cellulose
- Silicon Dioxide (Colloidal)
- Sodium Starch Glycolate
As you can see, the ingredient list is significantly different between these two levothyroxine 50mcg products.
Why You Should Stay On The Same Levothyroxine Brand
Not only can sensitivities to a certain ingredient (such as the sucrose in the Mylan product) cause problems, switching between generic manufactures could potentially cause major changes in your thyroid and TSH levels, which could theoretically cause either hypothyroidism or hyperthyroidism.
While most pharmacies and pharmacists will freely interchange between levothyroxine products, which is allowed under FDA substitution laws, it generally isn't recommended.
Levothyroxine is known as a narrow therapeutic index drug. A small change in dose can have a major impact on how the medication affects you. Remember that the dose of levothyroxine is dosed in micrograms, which is one one-thousandths of a milligram! The doses are extremely small.
Although the different manufacturers are making the same strength of levothyroxine, small differences in products (e.g. such as from the different inactive ingredients) could alter how your body dissolves, absorbs and utilizes the medication.
Look no further than the prescribing information for levothyroxine products for the proper recommendation:
"For patients who have recently initiated levothyroxine therapy and whose serum TSH has normalized or in patients who have had their dosage or brand of levothyroxine changed, the serum TSH concentration should be measured after 8— 12 weeks."
Even the prescribing information recommends having your TSH levels checked after a change in dose or brand. This recommendation/counseling point is often overlooked unfortunately.
Getting The Same Manufacturer Of Levothyroxine Every Time
You have two options to ensure you get the same manufacturer of levothyroxine every time you get a fill of the medication:
- Ask your pharmacy to put a note on your file to get the same levothyroxine product every fill. This is sometimes known as a "NDC preference".
- Ask your doctor to write for the specific levothyroxine product.
In most situations, the pharmacy should be able to accommodate your request based on the availability of the product you need. If they are unwilling, ask the doctor to write specifically for the product you need. Most states have provisions where a doctor can write for a specific product to be dispensed.
In New York for example, the doctor can indicate on the prescription 'DAW', meaning 'Dispensed As Written'. If you have a prescription, that says for example: "Levothyroxine 50 mcg, Sandoz brand, DAW", it must legally be dispensed that way.
As mentioned above, it is important to stay on the same generic manufacturer of levothyroxine to reduce the variability between products. If your pharmacy is constantly switching manufacturers of levothyroxine, be sure to speak with them about your concerns.
Summary
- There are many different manufactures of generic levothyroxine products.
- Most generic levothyroxine products contain different inactive ingredients.
- Small differences in levothyroxine products can have a significant impact.
- You ideally should not switch between different levothyroxine products.
- Ask your pharmacy to keep you on the same manufacturer or ask your doctor to write specifically for one manufacturer on your prescription.
