The FDA has determined that 3 generic formulations of levothyroxine are therapeutically equivalent to brand-name formulations. Some brand-name manufacturers have objected, and endocrine organizations have expressed their concern.
See levothyroxine addendum

The media recently reported that the FDA has threatened to withdraw Synthroid from the market, alarming many physicians and patients.

In our October 26, 2015 article on drugs for hypothyroidism (Med Lett Drugs Ther 2015; 57:147), we said that levothyroxine should be taken on an empty stomach with a full glass of water 30-60 minutes (60 is preferable) before breakfast. We should have added that taking the drug consistently at bedtime, at least 3 hours after the last meal, is an alternative that some patients may find more convenient.

Primary hypothyroidism is usually the result of Hashimoto's (autoimmune) thyroiditis, thyroidectomy, or radioactive iodine therapy. Treatment of hypothyroidism with replacement doses of thyroid hormone is usually lifelong. Levothyroxine (LT4; synthetic thyroxine; Synthroid, and others) is the drug of choice.1

Primary hypothyroidism is usually the result of Hashimoto's thyroiditis, thyroidectomy for hyperthyroidism, goiter or cancer, or radioactive iodine therapy for hyperthyroidism.

The equivalence of generic drugs to their brand-name precursors continues to be controversial. The last Medical Letter review of this subject (2002) concluded that well-documented therapeutic inequivalence between brand-name and FDA-approved generic drugs had not been reported. Is that still true? New data have become available for some drugs.

Most patients with end-stage renal disease develop hyperphosphatemia, which can lead to secondary hyperparathyroidism, vascular calcification, and cardiovascular mortality. The FDA has approved sucroferric oxyhydroxide (Velphoro – Fresenius Medical Care), a chewable phosphate binder, for treatment of hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis. It is the first iron-based phosphate binder to be approved for this indication.

The FDA has approved 3 allergen extracts for sublingual administration as immunotherapy for allergic rhinitis confirmed by a positive skin test or in vitro testing for pollen-specific IgE antibodies: Oralair (Stallergenes S.A./Greer) and Grastek (Merck) for grass pollen-induced allergic rhinitis and Ragwitek (Merck) for short ragweed pollen-induced allergic rhinitis.

The FDA has approved Odactra (ALK), a sublingual allergen extract, for immunotherapy in adults 18-65 years old with house dust mite (HDM)-induced allergic rhinitis, with or without conjunctivitis. Odactra is the first sublingual allergen extract to be approved in the US for this indication. Three other sublingual allergen extracts were approved earlier (see Table 1).

The FDA has approved sodium zirconium cyclosilicate (Lokelma – AstraZeneca), an oral potassium binder that exchanges hydrogen and sodium for potassium in the gastrointestinal (GI) lumen, for treatment of non-life-threatening hyperkalemia in adults. Sodium zirconium cyclosilicate (SZC) is the third drug to be approved for this indication; sodium polystyrene sulfonate and patiromer (Veltassa) were approved earlier.