β-Adrenergic Receptor Antagonists
For a more detailed discussion of this topic, see β-Adrenergic Receptor Antagonists, Sec. 31.5–2, p. 3011 in Comprehensive Textbook of Psychiatry, 9th Edition.
Because of the innervations of many, if not most, peripheral organs and vasculature by the sympathetic division of the autonomic nervous system, their functions are ultimately controlled, in part, by one of the two major classes of adrenergic receptors, α-receptors (discussed in Chapter 2 on α-adrenergic receptor agonists) and β-receptors. These receptors are further subdivided based on their action and location, and they are located both peripherally and in the central nervous system (CNS). Shortly after being introduced for cardiac indications, propranolol (Inderal) was reported to be useful for agitation, and its use in psychiatry spread rapidly. The five most commonly used β-receptor antagonists in psychiatry are propranolol, nadolol (Corgard), metoprolol (Lopressor, Toprol), pindolol (Visken), and atenolol (Tenormin).
Pharmacologic Actions
The β-receptor antagonists differ with regard to lipophilicities, metabolic routes, β-receptor selectivity, and half-lives (Table 3-1). The absorption of the β-receptor antagonists from the gastrointestinal tract is variable. The agents that are most soluble in lipids (i.e., are lipophilic) are likely to cross the blood–brain barrier and enter the brain; those agents that are least lipophilic are less likely to enter the brain. When CNS effects are desired, a lipophilic drug may be preferred; when only peripheral effects are desired, a less lipophilic drug may be indicated.
Whereas propranolol, nadolol, pindolol, and labetalol (Normodyne, Trandate) have essentially equal potency at both the β1– and β2-receptors, metoprolol and atenolol have greater affinity for the β1-receptor than for the β2-receptor. Relative β1-selectivity confers few pulmonary and vascular effects of these drugs, although they must be used with caution in persons with asthma because the drugs retain some activity at the β2-receptors.
Pindolol has sympathomimetic effects in addition to its β-antagonist effects, which has permitted its use for augmentation of antidepressant drugs. Pindolol, propranolol, and nadolol possess some antagonist activity at the serotonin 5-HT1A receptors.
Therapeutic Indications
Anxiety Disorders
Propranolol is useful for the treatment of social phobia, primarily of the performance type (e.g., disabling anxiety before a musical performance). Data are also available for
its use in treatment of panic disorder, posttraumatic stress disorder, and generalized anxiety disorder. In social phobia, the common treatment approach is to take 10 to 40 mg of propranolol 20 to 30 minutes before the anxiety-provoking situation. A test run of the β-receptor antagonist can be tried before using it before an anxiety-provoking situation to be sure that the patient does not experience any adverse effects from the drug or the dosage. The β-receptor antagonists may blunt cognition in some people. The β-receptor antagonists are less effective for the treatment of panic disorder than are benzodiazepines or selective serotonin reuptake inhibitors (SSRIs).
its use in treatment of panic disorder, posttraumatic stress disorder, and generalized anxiety disorder. In social phobia, the common treatment approach is to take 10 to 40 mg of propranolol 20 to 30 minutes before the anxiety-provoking situation. A test run of the β-receptor antagonist can be tried before using it before an anxiety-provoking situation to be sure that the patient does not experience any adverse effects from the drug or the dosage. The β-receptor antagonists may blunt cognition in some people. The β-receptor antagonists are less effective for the treatment of panic disorder than are benzodiazepines or selective serotonin reuptake inhibitors (SSRIs).
Table 3-1 β-Adrenergic Drugs used in Psychiatry | ||||||||||||
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