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At the completion of this chapter, the reader will be able to:

  1. Differentiate between pharmacokinetics and pharmacodynamics.

  2. Describe the process of drug development, regulation, and distribution.

  3. Describe controlled substances and their potential for abuse.

  4. Recognize the three different names used for drugs.

  5. Describe the various modes of action of drugs.

  6. Describe the various drug receptor sites within the body.

  7. Outline the various administration routes used for drug delivery.

  8. Understand the potential effects of physical agents and exercise on drug delivery.



Pharmacology is the broad area of study that deals with how chemical substances affect living molecular tissue and how drugs affect specific patient populations (Table 9-1). Drug therapy is one of the mainstays of modern treatments, and physical therapists often encounter patients taking various medications. The Guide to Physical Therapist Practice1 identifies clinical pharmacology as an essential component of appropriate patient monitoring, modality delivery, and communication among medical professionals. Therefore, the physical therapist needs to have a working knowledge of pharmacology because of the number of drugs currently on the market and the number of physical therapy patients likely to have been prescribed medications. As physical therapists attempt to account for the effects of their interventions, it becomes apparent that they must also understand the effect and potential interactions of all pharmacological interventions. The prescription drug–writing privileges exercised by select military therapists and the physical therapy profession’s evolution promote consideration of an expanded pharmacological role in physical therapy practice.2 Although the dispensing of medications is currently out of the scope of practice for the vast majority of physical therapists, questioning the patient about prescribed medication use can reveal medical conditions that the patient might not consider related to the present problem, as the prescribed medications may be for preexisting conditions that are not directly related to the condition being treated with physical therapy. This information also can provide the clinician with possible reactions that the patient may have to exercise or other treatment procedures and clinical findings. For example:

  • Pain medications, muscle relaxants, and nonsteroidal anti-inflammatory drugs (NSAIDs) can mask signs and symptoms, thereby affecting examination findings and increasing the potential for injury during the performance of prescribed exercises. However, if the patient has a significant amount of pain, appropriate use of these medications may enhance treatment, allowing a more rapid progression than would otherwise be possible. However, as the patient improves, the need for this medication should lessen.

  • Certain medications can produce changes in musculoskeletal structures. For example, prolonged use of corticosteroids may produce osteoporosis and a weakening of connective tissues.

  • A patient undergoing anticoagulant therapy has a reduced clotting ability and is more susceptible to bruising or hemarthrosis. It is worth remembering that aspirin and aspirin-based products have an anticoagulant effect.

TABLE 9-1Pharmacology Terms and Definitions

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