Since 1972, the US Food and Drug Administration (FDA) has been engaged in a methodical review of OTC ingredients for both safety and efficacy. There have been two major outcomes of this review: (1) Ingredients designated as ineffective or unsafe for their claimed therapeutic use are being eliminated from OTC product formulations (eg, antimuscarinic agents have been eliminated from OTC sleep aids; attapulgite and polycarbophil can no longer be marketed as OTC antidiarrheal products); and (2) agents previously available by prescription only have been made available for OTC use because they were judged by the review panel to be generally safe and effective for consumer use without medical supervision (Table 63–1). The prescription-to-OTC switch process has significantly enhanced and expanded self-care options for US consumers. More than 100 OTC active ingredients or dosages are on the market today that were previously available only by prescription. Other OTC ingredients previously available in low doses only are now available in original prescription strength formulations (eg, ranitidine 150 mg, famotidine 20 mg). Examples of other prescription medications with the potential for future OTC reclassification include oral contraceptives, nicotine replacement therapy (oral inhaler, nasal spray) for smoking cessation, proton-pump inhibitors (pantoprazole) for heartburn, and second-generation nonsedating antihistamines (desloratadine) for relief of allergy and cold symptoms. The prescription-to-OTC reclassification process is both costly and rigorous, and only select prescription medications are appropriate candidates for a switch (eg, a consumer can self-diagnose and safely treat the condition). For example, the cholesterol-lowering agents lovastatin and pravastatin were denied OTC status on the basis that these agents could not be used safely and effectively in an OTC setting. The nonprescription drug advisory committee believed that diagnosis and ongoing management by a health care professional was necessary for the management of hyperlipidemia, a chronic, asymptomatic condition with potentially life-threatening consequences. In a similar recommendation, oral acyclovir for OTC use in the treatment of recurrent genital herpes was not approved because of concerns about misdiagnosis and inappropriate use leading to increased viral resistance.
There are three reasons why it is essential for clinicians to be familiar with the OTC class of products. First, many OTC medications are effective in treating common ailments, and it is important to be able to help the patient select a safe, effective product. Because health care insurance practices encourage clinicians to reduce costs, many providers will recommend effective OTC treatments, since these medications are rarely paid for by health plans. Second, many of the active ingredients contained in OTC medications may worsen existing medical conditions or interact with prescription medications (see Chapter 66, Important Drug Interactions & Their Mechanisms). Finally, the misuse or abuse of OTC products may actually produce significant medical complications. Phenylpropanolamine, for example, a sympathomimetic previously found in many cold, allergy, and weight control products, was withdrawn from the US market by the FDA based on reports that the drug increased the risk of hemorrhagic stroke. Dextromethorphan, an antitussive found in many cough and cold preparations, has been increasingly abused in high doses (eg, >5–10 times the recommended antitussive dose) by adolescents as a hallucinogen. Although severe complications associated with dextromethorphan as a single agent in overdose are uncommon, many dextromethorphan-containing products
TABLE 63–1 Selected agents switched from prescription to over-the-counter status by the US Food and Drug Administration (2006–2017).