Onychomycosis is caused most commonly by Trichophyton rubrum or T. mentagrophytes. About 10% of all persons worldwide and 40% of those ≥60 years old are believed to have the disease. Risk factors include older age, diabetes, poor peripheral circulation, smoking, HIV infection, psoriasis, and immunosuppression. Left untreated, onychomycosis can cause nail plate destruction, ingrown nails, and (particularly in patients with diabetes) secondary infections. Guidelines on treatment of onychomycosis have been published.

Breaking drug tablets in half is a common practice. Since our last article on this subject, some new data have become available.

The 1990 labeling for Norpramin, the Merrell Dow brand of the tricyclic antidepressant desipramine, reports the occurrence of sudden death in an eight-year-old child treated with the drug. Desipramine is also available as Pertofrane (Rorer) and generically.

The FDA has removed a boxed warning from the labeling of products containing the sodium-glucose co-transporter 2 (SGLT2) inhibitor canagliflozin (Invokana, Invokamet, Invokamet XR) that described an increased risk of lower limb amputation associated with use of the drug. Package inserts for canagliflozin products still contain a standard warning about a risk of lower limb amputation.

Tinidazole (Tindamax - Mission Pharmacal), an oral antiprotozoal drug available in the US since 2004 for treatment of trichomoniasis, giardiasis, amebiasis and amebic liver abscess, was recently approved by the FDA for treatment of bacterial vaginosis.

The FDA has approved patiromer (Veltassa – Relypsa), an oral potassium binder, for treatment of hyperkalemia. It is the first drug to be approved for this indication since the cation-exchange resin sodium polystyrene sulfonate (Kayexalate, and others) in 1958. Patiromer is not indicated for emergency correction of life-threatening hyperkalemia. Sodium zirconium cyclosilicate, another oral potassium binder, is currently being reviewed by the FDA; a decision on its approval is expected in May 2016.

The oral sphingosine 1-phosphate (S1P) receptor modulator etrasimod (Velsipity – Pfizer) has been approved by the FDA for treatment of moderately to severely active ulcerative colitis in adults. It is the second oral S1P receptor modulator to be approved in the US for this indication; ozanimod (Zeposia) was the first.

The FDA has announced that prescribers, pharmacies, and patients are no longer required to participate in a Risk Evaluation and Mitigation Strategy (REMS) program for the second-generation antipsychotic drug clozapine (Clozaril, and others).

Trospium chloride (Sanctura - Indevus/Odyssey) has been approved by the FDA for treatment of overactive bladder with symptoms of urge urinary incontinence, urgency and urinary frequency. It has been available in Europe for many years.

The FDA has approved efinaconazole 10% solution (Jublia – Valeant) for topical treatment of toenail onychomycosis due to Trichophyton rubrum and/or Trichophyton mentagrophytes. It is the first topical triazole antifungal drug to be approved for this indication. A topical oxaborole antifungal solution, tavaborole 5% (Kerydin – Anacor), also recently approved by the FDA for the same indication will be reviewed in a future issue.