Over-the-Counter Pain Relievers

Over-the-counter (OTC) pain relievers are sold without a doctor s prescription and can be found at local pharmacies, grocery stores, and mini-marts. They are not nearly as potent as prescription pain relievers such as morphine and Demerol (see Chapter 3), so they are most often used to treat mild to moderate pain. OTC pain relievers are not as addictive as prescription pain relievers. Nonetheless, there are several side effects of OTC pain relievers that can be serious. 

However, the pathway of pain signals arising from tissue and then traveling to the spinal cord and brain is not a one-way street. It turns out that nerve endings in the skin or tissue can also release peptides such as substance P, which can alter the activity of immune cells or cause blood vessels to dilate. This causes swelling or further alters the pain response. Thus, not only does damaged tissue communicate with the central nervous system, but the central nervous system also sends chemical feedback to the site of injury or tissue damage. 

The prostaglandins produced by the COX enzyme have uses in the body in addition to their role in pain response, including maintaining the health of the stomach lining, regulating blood flow to the kidneys, and enabling specialized blood cells called platelets to initiate the process of blood clotting. Because the COX enzyme is responsible for all of these other functions, there are some potentially harmful side effects of NSAIDs, as will be discussed below. 

Aspirin takes approximately 30 minutes to start working after you take it by mouth. When taken on a full stomach, it may take longer to work. Aspirin tablets are manufactured to contain anywhere from 80 to 1,000 milligrams (mg) of aspirin each. Maximum pain relief is observed in adults with a dosage of 3,600 to 5,400 mg of aspirin per day, and the ability of aspirin to relieve pain lasts for about 4 to 6 hours. 

Aspirin has some beneficial effects when mixed with caffeine, because caffeine increases the pain-relieving and anti-inflammatory effects of aspirin. Brand names of pain relievers that combine aspirin and caffeine include Alka-Seltzer , Anacin , and Cope Analgesic Pain Reliever. 

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The following model is a representation of ibupvofen, a common over-the-counter pain reliever. Indicate the positions of the multiple bonds, and draw a skeletal structure (gray = C, red = O, ivory = H). 

Analysis of ibuprofen, the active ingredient in several over-the-counter pain relievers, shows that it contains 75.7% carbon, 8.8% hydrogen, and 15.5% oxygen. The mass spectrum of ibuprofen shows that its molar mass is less than 210 g/mol. Determine the chemical formula of this compound. 

FDA (2006) FDA Proposes Labeling Changes to Over-the-Counter Pain Relievers. FDA News, http //www.fda. gov/bbs/topics/ NEWS/2006/ NEW01533.html (accessed May 28th, 2007). 

While many commercially available preparations contain only melatonin, many others contain a combination of this hormone with other active ingredients. Some of these other ingredients may be vitamins such as pyri-doxine, while others are natural remedies such as kava root and valerian. It is even available combined with acetaminophen, a common over-the-counter pain reliever. Frequently, the long-term effects and safety of these other ingredients are not known. Even less is known about any possible interactions between these substances and melatonin, because melatonin has been available and used commercially for only a short period of time. Many experts have suggested that it would be preferable to test melatonin in controlled studies to determine if it is effective and safe before it was released on the market and used by millions of people. 

Oxycodone is a strong prescription analgesic and, as such, it is not advisable to take oxycodone in combination with any other pain medications, including common over-the-counter pain relievers like Tylenol or Advil. If oxycodone taken as prescribed does not relieve the pain... 

NONE All over-the-counter pain relievers (i.e., aspirin, acetaminophen, ibuprofen, naproxen, etc.), prescription antidepressants, anticonvulsants, muscle relaxants (except benzodiazepines), migraine medications, steroids, celecoxib, BoTox, herbal remedies, tramadol, local caine family (except cocaine)... 

Phenacetin is an analgesic compound having molecuiar formula C10H13NO2. Once a common component in over-the-counter pain relievers such as APC (aspirin, phenacetin, caffeine), phenacetin is no longer used because of its liver toxicity. Deduce the structure of phenacetin from its NMR and IR spectra. 

Dependence on caffeine, although a lesser central nervous system stimulant, is an instructive addiction to look at in many ways because it illustrates a number of additional properties about addiction itself. For example, although the price for coffee has increased manyfold over the past ten to fifteen years, sales have not diminished. To the addict, money is no object when it comes to obtaining his or her substance of choice. Caffeine (present in coffee, tea, colas, other soft drinks, chocolate, and some over-the-counter pain relievers and wakefulness aids) is generally viewed as a harmless substance therefore, what harm can an addiction to caffeine do There are two kinds of harm ... 

In 1994, the EDA approved another compound for sale as an over-the-counter pain reliever. Naproxen, marketed under the trade names Aleve and Anaprox , exerts its effects for a longer time in the body (8-12 hours per dose) than ibuprofen (4-6 hours per dose) or aspirin and acetaminophen (4 hours per dose). However, the chances for causing slight intestinal bleeding and stomach upset are greater with naproxen than with ibuprofen, and naproxen is not recommended for use by children under age 12. 

PRACTICE the skill 1. 22 Below are the structures of two common over-the-counter pain relievers. Determine the hybridization state of each carbon atom in these compounds ... 

Practice Problem A Determine the percent composition by mass of acetaminophen (C8H9NO2), the active ingredient in over-the-counter pain relievers such as Tylenol (Rgure 3.1). 

Practice Problem A The active ingredient in Tylenol and a host of other over-the-counter pain relievers is acetaminophen (CgHgNOi). Determine the total number of sigma and pi bonds in the acetaminophen molecule. 

Diuretics—These are drugs which act to increase the output of sodium and water in the urine, and are often used to treat disorders of the heart, kidneys, or liver which cause edema. A majority of the diuretics act up the kidneys by depressing the sodium reabsorbed. Thus, sodium remaining in the urine carries more water out of the body with it. Diuretics include thiazides, furosemide, and ethacrynic acid. Xanthine diuretics are mild diuretics but they are used by many people—perhaps unknowingly—since they are the caffeine, theophylline, and theobromine present in tea, coffee, cola and other soft drinks, cocoa, and many over-the-counter pain relievers. Moreover, water and ethyl alcohol (alcoholic beverages) can act as diuretics by inhibiting the release of ADH. 

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