Adrenergic receptors anxiety disorders

Bupropion (100 mg p.o. b.i.d.) is indicated in the treatment of depression. It is reserved for patients who cannot tolerate or have not responded to other medications. Bupropion does not alter the uptake of serotonin, has an equivocal effect on the uptake of norepinephrine, but blocks the uptake of dopamine. Bupropion has no affinity for alpha-1 and alpha-2-adrenergic receptors, H,-histamine receptors, muscarinic cholinergic receptors, or D2-dopaminergic receptors. It does not cause sedation or orthostatic hypotension. However, because it is structurally related to amphetamine, it may cause insomnia, agitation, and anxiety shortly after initiation of therapy. Bupropion lowers the seizure threshold and hence is contraindicated in patients with a history of seizure disorder (see also Tables 5 through 7). 

The antihistamine hydroxyzine is an effective antianxiety agent, but only at doses (-400 mg/day) that produce marked sedation (see Chapter 24). Propranolol and metoprolol, lipophilic fi adrenergic receptor antagonists that enter the CNS, can reduce the autonomic symptoms (nervousness and muscle tremor) associated with specific situational or social phobias but do not appear to be effective in generalized anxiety or panic disorder (see Chapter 10). Similarly, other antiadrener-gic agents, including clonidine, may modify autonomic expression of anxiety but are not demonstrably usfful in the treatment of severe anxiety disorders. 

For panic disorder, tricychc antidepressants and MAO inhibitors, as well as high-potency benzodiazepines (notably alprazolam, clonazepam, and lorazepam) (see Chapter 16), are effective in blocking the autonomic expression of panic itself, thereby facilitating a comprehensive rehabilitation program. Imipramine and phenelzine are well-studied antidepressants for panic disorder. SSRIs also may be effective, but /3 adrenergic receptor antagonists, buspirone, and low-potency benzodiazepines usually are not, and bupropion can worsen anxiety. 

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