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100 FOCUS ON PHARMACOLOGY PEER REVIEWED veterinary medicine; however, many medications have anticholinergic effects as part of their pharmacologic profile. Anticholinergic effects are common for many tricyclic antidepressants (TCAs), and although they have the potential for undesirable events, in this example, a medication with some anticholinergic effect may be beneficial. Additionally, a region in the central nucleus of the amygdala contributes to salivation, suggesting that medications that affect serotonin and norepinephrine regulation will be useful. Accordingly, amitriptyline or clomipramine may be rational choices, but clomipramine comes in a canine form (Clomicalm) with scored tablets, is a relatively more specific compound because of its intermediate metabolites, and affects a wide range of receptor types. It may be a good choice here. If the dog is vocalizing or blocks or destroys doors through which clients leave, the behaviors are associated with affiliation and social needs and loss. A medication that has a profound effect on 5HT receptors, especially the 5-HT 1A receptors that are involved in social anxieties, may benefit the patient. Unfortunately, medication costs and formulations change frequently. What do we do if clients cannot afford or obtain any formulation of clomipramine, a particular problem in the United States in the past few years? By reverting to the idea that distress about absences lies at the core of separation anxiety, pick a selective serotonin reuptake inhibitor (SSRI) affecting the 5-HT 1A receptor because this receptor TABLE 2 Relative Medication Effects on Most Common Receptors (Antagonist Role Unless Otherwise Specified) 8–10 PARENT COMPOUND 5-HT 1A 5-HT 1B 5HT1D 5HT2A 5-HT 2B 5-HT 2C 5-HT 3 α1A α 2A α 1B α 2B D1 D2 H1 a ACh TCAs Imipramine ++ ++ ++ +++ +++ Amitriptyline + +++ +++ +++ +++ +++ Nortriptyline + +++ +++ +++ +++ +++ Clomipramine +++ +++ +++ +++ + ++ +++ +++ SSRIs Fluoxetine +++ + + + + ++ + + + Paroxetine ++ + +++ Sertraline +++ +++ Fluvoxamine b Citalopram +++ SARIs Trazodone ++ +++ + + + α-Agonists Clonidine + + ++ +++ OTM dexmedetomidine +++ β-blockers/antagonists Propranolol ++ ++ Pindolol ++ ++ +, some effect; ++, moderate effect; +++, large effect; ACh, acetylcholine; SARI, serotonin antagonist/reuptake inhibitor; SSRI, selective serotonin reuptake inhibitor; TCA, tricyclic antidepressant. a Potency at the H1 receptor correlates with weight gain in humans. 9 b Primarily affects transporters.