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This chapter discusses a chemically diverse group of substances that exert several distinct pharmacological properties: (1) the ability to decrease inflammation, (2) the ability to relieve mild-to-moderate pain (analgesia), (3) the ability to decrease elevated body temperature associated with fever (antipyresis), and (4) the ability to decrease blood clotting by inhibiting platelet aggregation (anticoagulation). These drugs are commonly referred to as nonsteroidal anti-inflammatory drugs (NSAIDs) to distinguish them from the glucocorticoids (i.e., the other main group of drugs used to treat inflammation). Obviously, the term NSAID does not fully describe the pharmacological actions of these drugs; a more inclusive terminology should also mention the analgesic, antipyretic, and anticoagulant effects. However, NSAIDs is the accepted term, and it is used throughout this chapter.

Because of these drugs’ analgesic and antiinflammatory effects, patients receiving physical rehabilitation often take NSAIDs for any number of problems. These drugs are a mainstay in the treatment of many types of mild-to-moderate pain, and NSAIDs are especially useful in treating pain and inflammation occurring in acute and chronic musculoskeletal disorders. Other patients are given NSAIDs to treat fever or to prevent excessive blood clotting. Consequently, you will notice that these drugs are used quite frequently in various patient populations, with the specific therapeutic goal related to each patient's individual needs. You should therefore understand the mechanism of action, applications, and effects of aspirin, acetaminophen, and other NSAIDs.


Aspirin (acetylsalicylic acid) is usually considered the original NSAID (Fig. 15-1). Newer NSAIDs are often compared to aspirin in terms of efficacy and safety. Acetaminophen is similar to aspirin and other NSAIDs in its ability to decrease pain and fever, but it is not considered an NSAID because it lacks anti-inflammatory and anticoagulant properties. Other differences between aspirin, other NSAIDs, and acetaminophen are addressed later in this chapter.

Figure 15-1

Structure of aspirin.

For years, it was a mystery how a drug like aspirin could exert such a diverse range of therapeutic effects. How could one drug influence so many different systems—effectively alleviating pain and inflammation, decreasing fever, and even affecting blood clotting? This issue was essentially resolved in the early 1970s, when researchers found that aspirin and the other NSAIDs exert most, if not all, of their therapeutic effects by interfering with the biosynthesis of a group of endogenous compounds known collectively as the prostaglandins.1,2 The next section presents a brief discussion of prostaglandins and similar endogenously produced substances to help you understand how these drugs work.


Prostaglandins are a group of lipidlike compounds that exhibit a wide range of physiological activities.25 With the exception of the red blood cell, virtually every type of living cell ...

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