A physical therapy clinic is associated with a wellness center where the practice provides consulting advice on aerobic and resistance exercise training. D.J. is a 47-year-old man who works as an accountant for a local business. Recently, his physician told him that he had hypertension and that his “good” cholesterol was low. The physician suggested that D.J. begin a regular exercise program to lower his blood pressure and to help improve his cholesterol profile. At his last medical evaluation, measurements of resting blood pressure and heart rate were 135/84 mm Hg and 84 beats per minute (bpm), respectively. His body mass index was 29 kg/m2. D.J. is currently taking no prescription drugs. The physical therapist developed an aerobic and upper extremity strength training program that D.J. has been performing three times per week during the past month, without incident. D.J. arrived today (Monday) to participate in his program. He stated that he missed Friday due to a cold. Over the weekend, he began taking over-the-counter cold medications to relieve his symptoms. These preparations included the topical decongestant Afrin (oxymetazoline) to relieve nasal congestion and oral Advil Cold and Sinus (ibuprofen and pseudoephedrine). During the conversation, the therapist notices that D.J. is moving his left arm in a circular motion and rubbing his left shoulder. He states that his left shoulder has been hurting intermittently for the past couple days just as it is now.
Drugs with sympathomimetic and sympatholytic properties are used in a broad spectrum of pathophysiologic conditions to either mirror or inhibit the role of the sympathetic nervous system (SNS) and catecholamine neurotransmitters in the central nervous system (CNS). Drugs with sympathomimetic or sympatholytic properties are found in many other drug groups and are discussed in several chapters. Sympathomimetic drugs are prescribed to treat upper and lower respiratory dysfunctions (Chapter 35). Sympatholytic drugs are used in the treatment of various cardiovascular pathophysiologies (Chapters 7, 8, 9, 10). Less obvious drugs that have either sympathomimetic clinical uses or adverse effects include tricyclic antidepressants and MAOA inhibitors used to treat depression (Chapter 19) and MAOB and COMT inhibitors used to treat parkinsonism (Chapter 17).
Receptors found in the SNS may be divided into alpha (α) or beta (β) adrenergic receptors (adrenoceptors) or dopamine (D) receptors. Drugs that bind to these receptors and augment the system are called sympathomimetics, while those that bind to these receptors and inhibit or prevent the binding of endogenous ligands are called sympatholytics. The sympathomimetics constitute an important group of agonists used for cardiovascular, respiratory, and other conditions. Sympathomimetics are readily divided into subgroups based on their spectrum of affinity for α, β, or D receptors. Alternatively, these agents may be divided into subgroups based on whether their mode of action is direct ...