Therapeutic & Toxic Potential of Over-the-Counter Agents
A 66-year-old man presents to his primary care provider for worsening shortness of breath, chest congestion, and symptoms of a severe cold (cough, rhinorrhea, nasal congestion, drowsiness) over the past week. His past medical history is significant for heart failure, hypertension, and hyperlipidemia. His current medications include metoprolol succinate 50 mg daily, lisinopril 20 mg daily, atorvastatin 20 mg daily, furosemide 40 mg daily, and potassium chloride 20 mEq daily. The patient reports excellent compliance with his prescribed medications but admits to taking several over-the-counter (OTC) medications over the past 5 days for his recent cold symptoms, including Alka-Seltzer Plus Cold Formula (2 tablets every 4 hours during the day), Sudafed (60 mg every 6 hours), and Advil PM (2 tablets at bedtime). His social history is significant for alcohol use (3–4 beers/night). His vital signs include the following: afebrile, blood pressure 172/94 mm Hg, pulse 84 bpm, respiratory rate 16/min. On physical examination an S3 gallop is heard; 3+ pitting edema is noted in his lower extremities, and a chest examination reveals inspiratory rales bilaterally. What medications do OTC “cold” preparations typically contain? Which of the OTC medications might have contributed to the patient’s current hypertension? Are any of these preparations implicated in the signs of heart failure?
In the USA, medications are divided by law into two classes: those restricted to sale by prescription only and those for which directions for safe use by the public can be written. The latter category constitutes the nonprescription or over-the-counter (OTC) medications. This category does not include supplements (vitamins, minerals, herbals, and botanicals), which are subject to different regulatory requirements (see Chapter 64). In 2013, the American public spent approximately 33.1 billion on OTC products to medicate themselves for ailments ranging from acne to warts. These products contain approximately 800 active ingredients in various forms and combinations.
It is apparent that many OTC medications are no more than “me too” products advertised to the public in ways that suggest significant differences between them. For example, there are over 100 different systemic analgesic products, almost all of which contain aspirin, acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, or a combination of these agents as primary ingredients. They are made different from one another by the addition of questionable ingredients such as caffeine or antihistamines; by brand names chosen to suggest a specific use or strength (“women’s,” “migraine,” “arthritis,” “maximum”); or by special dosage formulations (enteric-coated tablets, geltabs, liquids, orally disintegrating strips and tablets, sustained-release products, powders, seltzers). There is a price attached to all of these features, and in most cases a less expensive generic product can be equally effective. It is probably safe to assume that the public is generally overwhelmed and confused by the wide array of products presented and will probably use those that are most heavily advertised.
Over the past four decades the 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. Indeed, more than 100 OTC active ingredients or dosages are on the market today that were available only by prescription less than 40 years ago. Some agents such as docosanol and the nicotine polacrilex lozenge have bypassed the prescription route altogether and have been released directly to the OTC market. Other OTC ingredients previously available in low doses only are now available in higher-strength or original prescription strength formulations. 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, levocetirizine) for relief of allergy and cold symptoms. The frequency of prescription-to-OTC switches, while commonplace in the mid-1990s, has largely declined over the past decade. The prescription-to-OTC reclassification process is both costly and rigorous and fewer 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.