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

Irritable bowel syndrome (IBS) is a common disorder characterized by recurrent abdominal pain and altered bowel habits, often accompanied by bloating. IBS is classified by its predominant bowel symptom: constipation (IBS-C), diarrhea (IBS-D), mixed type (IBS-M), or unclassified (IBS-U). Since the exact cause of IBS is unknown, the goal of treatment is symptom control. Some over-the-counter (OTC) products and prescription drugs for IBS are listed in Tables 1-4. The safety of these drugs during pregnancy and lactation is described in Table 5 (online only).

With the possibility that chemical weapons may be used against United States armed forces in the Persian Gulf, the military has taken steps to protect our troops against poison gas, particularly ''nerve agents';'; (MA Dunn and FR Sidell, JAMA, 262:649, 1989).

Mirtazapine (mir taz a peen; Remeron - Organon) has been approved by the US Food and Drug Administration for treatment of depression. A tetracyclic piperazinoazepine, it is an analog of mianserin, an antidepressant available in Europe, but is structurally unrelated to antidepressants previously available in the USA.

The FDA has approved rivaroxaban (Xarelto – Janssen), an oral direct factor Xa inhibitor, for prevention of deep vein thrombosis (DVT) in patients undergoing knee or hip replacement surgery.

The FDA has approved Sinuva (Intersect ENT), a sinus implant that gradually releases the corticosteroid mometasone furoate over a 90-day period, for treatment of nasal polyps in adults who have had ethmoid sinus surgery. Propel, a sinus implant that releases mometasone furoate over 30 days, is FDA-approved to maintain the sinus opening after ethmoid sinus surgery; it is marketed by the same manufacturer as Sinuva.

Tofersen (Qalsody – Biogen), an intrathecally administered antisense oligonucleotide, has received accelerated approval from the FDA for treatment of amyotrophic lateral sclerosis (ALS) in adults who have a mutation in the superoxide dismutase 1 (SOD1) gene. About 2% of patients with ALS have mutations in the SOD1 gene. Tofersen is the first drug to be approved in the US that targets a genetic cause of ALS. Accelerated approval of the drug was based on the surrogate endpoint of a reduction in plasma neurofilament light chain, which is considered likely to predict clinical...

The FDA has approved perfluorohexyloctane ophthalmic solution (Miebo – Bausch+Lomb) for treatment of dry eye disease. Available only by prescription, Miebo is the first ophthalmic product to be approved in the US that specifically targets tear evaporation caused by meibomian gland dysfunction. An ophthalmic solution with a similar name, Meibo Tears (Vista), which contains 0.6% propylene glycol, is available over the counter for dry eye relief.

The FDA recently approved three new drugs for treatment of hyperlipidemia. Ezetimibe (ez et' i mibe; Zetia) is the first in a new class of drugs that inhibit intestinal absorption of cholesterol. Extended-release lovastatin (Altocor) is a new formulation of lovastatin (Mevacor, and others). Extended-release niacin plus (immediate-release) lovastatin (Advicor) is the first fixed-dose combination of lipid-lowering drugs.

Duloxetine hydrochloride (Cymbalta - Lilly), a selective serotonin and norepinephrine reuptake inhibitor (SNRI), has been approved by the FDA for treatment of major depressive disorder in adults, and more recently for diabetic peripheral neuropathy as well. The Medical Letter will review its role in diabetic neuropathy in a future issue.