In general, generic medicines are often equivalent to brand name medicines and are usually provided at a much cheaper rate and usually, can be recommended.
However, the case is different with thyroid hormone replacement, as the different brands of thyroid hormones have different fillers and dyes that affect the absorption and metabolism of the thyroid hormone.
Because a small change in the absorption of levothyroxine may make a big difference in both thyroid function tests and how the patient feels, Dr. Friedman in general recommends being on brand name thyroid hormone (T4) replacement, such as Synthroid, Levoxyl, or Unithroid for patients on T4 replacement. This is especially important because pharmacies can substitute the supplier of a generic form of levothyroxine with another one and not notify the patient. The patient may notice that the pill looks different but he or she otherwise does not know that it is a different formulation, and all of the sudden the patient's thyroid function tests may change.
Again for this reason, in the past Dr. Friedman has recommended brand name levothyroxine replacement only. However, a recent change by the company that makes Unithroid, Jerome Stevens Pharmaceuticals, may be a major benefit for patients. Unithroid used to be available by direct mail order prescription at a reduced rate and Dr. Friedman used this direct order heavily for his patients. He was recently notified that this mail order prescription would be terminated and that brand-name Unithroid might be more difficult to get. However, this information did contain a note that generic levothyroxine, if it is written as “Lannett brand generic levothyroxine”, is the same formulation as Unithroid, an excellent brand of levothyroxine. The formulation of Unithroid can be therefore obtained at generic prices, and some patients' insurance will only cover generic thyroid medicine.
Therefore, to ensure continuous supply of levothyroxine that is actually Unithroid, the patient's doctor can write levothyroxine generic and then in parentheses "Lannett brand.