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.

Intrauterine devices (IUDs) and the etonogestrel implant are the most effective reversible contraceptive methods available. Hormonal oral contraceptives, patches, rings, and injectables are also effective in preventing pregnancy. When used alone, barrier and behavioral methods generally have higher failure rates than other methods (see Table 1). Selection of a contraceptive method is usually based on patient-specific factors and personal preference

The motor symptoms of Parkinson's disease (PD) are caused primarily by degeneration of dopaminergic neurons in the substantia nigra. The nonmotor symptoms of the disease are thought to be caused by degeneration of other neurotransmitter systems. No disease-modifying drugs are available for treatment of PD.

Most patients with multiple sclerosis (MS) present with the relapsing-remitting form of the disease. Pharmacologic treatment usually includes a disease-modifying drug, corticosteroids for acute exacerbations, and other drugs for managing symptoms such as fatigue, depression, and pain. Early use of disease-modifying therapy has improved clinical outcomes.

Alzheimer's disease (AD) is the most common cause of dementia, but cognitive decline is also associated with other neurological conditions such as Parkinson's disease, dementia with Lewy bodies, vascular dementia, and frontotemporal dementia.

View the Comparison Table: Some Lipid-Lowering Drugs

The drugs of choice for treatment of common cardiac arrhythmias are listed in Tables 1 and 2. Some drugs are recommended for indications that have not been approved by the FDA.

The drugs of choice for treatment of fungal infections are listed in the table that begins on page 62. Some of the indications and dosages recommended here have not been approved by the FDA. More detailed guidelines for some of these infections are available online from the Infectious Diseases Society of America (www.idsociety.org).

Attention-deficit/hyperactivity disorder (ADHD) is a chronic neurodevelopmental disorder that has been diagnosed in up to 10% of school-age children in the US and frequently persists into adulthood. A study in a large Danish cohort found that ADHD was associated with higher mortality rates in children, adolescents, and adults, mainly due to accidents. Pharmacologic treatment of ADHD in children has been reported to decrease the risk of substance abuse in adolescents, and use of ADHD medications in adults has been associated with a reduced risk of serious traffic accidents and...