Atipamezole is a synthetic α2-adrenergic antagonist. It competitively inhibits α2-adrenergic receptors. Atipamezole is indicated for the reversal of the sedative and analgesic effects of Dexdomitor and Domitor in dogs. Adverse reactions: occasional vomiting may occur. At times, a period of excitement or apprehensiveness may be seen in dogs treated with atipamezole. Other effects of atipamezole include hypersalivation, diarrhea, and tremors.

Etoperidone is an atypical antidepressant introduced in Europe in 1977. The activity of etoperidone is made mainly by its major metabolite 1-(3'-chlorophenyl)piperazine (mCPP). mCPP binds with different affinity to most of the serotonergic receptors and adrenergic receptors. This metabolite is an agonist of 5-HT2c and an antagonist of 5-HT2a. Part of etoperidone structure contributes to the activity in the α-adrenergic receptors. Etoperidone has been studied for the treatment of depression, tremors in Parkinson, extrapyramidal symptoms and male impotence. It is not certain if it was ever approved and marketed but its current status is withdrawn.

Chlorpromazine pamoate (also known as chlorpromazine embonate) is a salt of pamoic acid and a chlorpromazine. Pamoate salts are used in pharmaceutical formulations because they show slow dissolution and are useful in formulations where extended duration of action is required. Chlorpromazine is a phenothiazine antipsychotic. It also exerts sedative and antiemetic activity. The precise mechanism whereby the therapeutic effects of chlorpromazine are produced is not known. It has a wide range of activity arising from its depressant actions on the CNS and its alpha-adrenergic blocking and antimuscarinic activities. Chlorpromazine is a dopamine inhibitor; the turnover of dopamine in the brain is also increased. There is some evidence that the antagonism of central dopaminergic function, especially at the D2-dopaminergic receptor, is related to therapeutic effect in psychotic conditions.

Besipirdine is a potential novel first-in-class oral treatment for over active bladder currently in Phase II development, with a mechanism of action clearly different from that of antimuscarinics. It was under evaluation by Aventis up to phase III for Alzheimer’s disease, involving the administration of the compound to over 1500 patients. However, this research has been discontinued. Besipirdine antagonizes alpha-2 and alpha-1 adrenoceptors and inhibits both norepinephrine and serotonin uptake. The most common adverse events were asymptomatic postural hypotension and asymptomatic bradycardia.

Proroxan is a non-selective а-adrenoblocker. Proroxan was found to prevent the development of hypertensive crises and improve cerebral bioelectrical parameters in most of hypertensive patients. Proroxan has been used as an antihypertensive and in the treatment of Ménière’s disease, motion sickness, and allergic dermatitis.

Tolonidine, 2(2-chloro-p-toluidino)-2-imidazoline-nitrate, is a substance chemically related to clonidine. In the anesthetized dog, tolonidine administered i.v. decreased the amplitude of ventricular contractions, reduced aortic blood flow and increased peripheral vascular resistances. In the bivagotomized pithed rat, tolonidine induced a long-lasting increase in blood pressure with no secondary hypotension, thus suggesting peripheral sympathomimetic properties, however, contractions of seminal vesicles in vitro were not obtained. The product proved to have no peripheral sympatholytic or parasympatholytic properties.

Setiptiline Maleate is a tetracyclic antidepressant that has been used in the treatment of depression. It has antihistamine and hypnotic–sedative effects, but almost no anticholinergic effects. It is a weak inhibitor of norepinephrine reuptake in vitro and strongly stimulates the release of central norepinephrine by blocking presynaptic α2-adrenoceptors similar to mianserin. It also acts as a 5-HT2A, 5-HT2C, and 5-HT3 receptor antagonist. Unlike most conventional antidepressants, it has no efficacy as a serotonin reuptake inhibitor. It can induce drowsiness and thirst, but it displays low toxicity. Setiptiline Maleate was launched in 1989 for the treatment of depression in Japan.

Lidamidine, also known as WHR-1142A and Lidaral, is an alpha2-adrenergic receptor agonist that inhibits intestinal secretion, reduces intestinal transit, and inhibits smooth muscle contraction. Lidamidine hydrochloride is used to treat diarrhoea and other gastrointestinal disorders. Lidamidine’s intestinal antisecretory effects are mediated through the activation of peripheral alpha-2 adrenoceptors. Lidamidine crosses the blood brain barrier poorly and is therefore devoid of the centrally mediated alpha-2 effects that have limited the use of other alpha-2 adrenoceptor agonists in the intestinal tract.

Levlofexidine is R-enantiomer of a α2A adrenergic receptor agonist Lofexidine. Levlofexidine (as a component of Lofexidine) can be used as a short-acting anti-hypertensive but is mostly used to help relieve symptoms of heroin or opiate withdrawal in opiate dependency. Lofexidine is approved in the United Kingdom but is still undergoing clinical trials in the United States. Levlofexidine showed an approximately 9-fold higher affinity than Dexlofexidine for the alpha 2-adrenoceptor-like binding sites in rat brain membranes identified by [3H]-clonidine and was 4 times more potent at displacing [3H]-prazosin from alpha 1-adrenoceptors. The possibility of using lofexidine to treat alcohol addiction withdrawal symptoms has been investigated and has not yet been shown to be an effective treatment.

Tramazoline is a sympathomimetic drug that is used in the form of tramazoline hydrochloride in nasal decongestant preparations. Tramazoline is an α-adrenergic receptor agonist that inhibits secretion of nasal mucus.