Trimazosin was originated by Pfizer and was licensed to Bristol-Myers Squibb worldwide except for Canada, Mexico and the USA. Trimazosin is a quinazoline antihypertensive agent structurally related to the selective alpha 1-adrenoceptor blocker prazosin. Trimazosin is an alpha adrenergic receptor antagonist. Compared with prazosin, trimazosin was a less potent but more efficacious hypotensive agent. At doses which caused equal or even greater hypotensive effects than those caused by prazosin, trimazosin caused less inhibition of pressor responses to phenylephrine. When administered during a maximum hypotensive response to prazosin, trimazosin caused an additional fall in pressure. Trimazosin is an effective antihypertensive when given by itself or in combination with a diuretic. Its ability to induce vasodilation without concomitant sodium retention or stimulation of the renin axis may be an important factor in its effectiveness. Trimazosin has the potential to cause sustained improvement in left ventricular function, both at rest and during exercise, in patients with chronic congestive heart failure (CHF).

Methyldopa is an aromatic-amino-acid decarboxylase inhibitor in animals and in man. Methyldopa is a medication that has been used to treat high blood pressure since the 1960s. Methyldopa is indicated in the treatment of moderate to severe hypertension, including that complicated by renal disease. Only methyldopa, the L-isomer of alpha-methyldopa, has the ability to inhibit dopa decarboxylase and to deplete animal tissues of norepinephrine. D-isomer is relatively inactive. In man the antihypertensive activity appears to be due solely to the L-isomer, which became generally known as methyldopa (Aldomet). About twice the dose of the racemate (Methyldopa anhydrous, (±)-; DL-alpha-methyldopa) is required for equal antihypertensive effect. Racemic alpha-methyldopa was shown to be much less effective or ineffective for the treatment of hypertension. The comparative study of the hypotensive effect of L-alpha-methyl-dopa (L-isomer) versus the racemic form was performed. The short-term hypotensive effects of the racemic form and the L-isomer of alpha-methyl-dopa were compared in 13 hospitalized patients with arterial hypertension. After a placebo period the active preparations in a fixed dose of 1.5 g daily were administered for three-day periods separated by a second placebo period of three days, the sequence of the active drugs being alternated. Both substances were shown to exert significant hypotensive effects. The L-isomer produced significant blood-pressure reductions irrespective of whether or not it was given first, whereas the racemic form was effective only when given first. The blood-pressure levels obtained with the L-isomer were throughout lower than those with the racemic form. Methyldopa is a centrally acting antihypertensive agent. It is metabolized to alpha-methylnorepinephrine in the brain, and this compound is thought to activate central alpha-2 adrenergic receptors

Rilmenidine (brand names Albarel, Hyperium, Iterium and Tenaxum) is an imidazoline derivative used for the treatment of hypertension. Rilmenidine, an oxazoline compound with antihypertensive properties, acts on both medullary and peripheral vasomotor structures. Rilmenidine shows greater selectivity for imidazoline receptors than for cerebral alpha2-adrenergic receptors, distinguishing it from reference alpha2-agonists. Rilmenidine is as effective in monotherapy as all other first line classes of drugs, including diuretics, beta-blockers, angiotensin converting enzyme (ACE) inhibitors, and calcium antagonists. It is well tolerated and can be taken in combination for greater efficacy. Sedation and dry mouth are not prominent side effects and withdrawal hypertension is not seen when treatment is stopped abruptly. In addition to a reduction in blood pressure, Rilmenidine has been shown to improve glucose tolerance, lipid risk factors, and insulin sensitivity.

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.

Etilefrine is a cardiac stimulant used as an antihypotensive. Intravenous infusion of this compound increases cardiac output, stroke volume, venous return and blood pressure in man and experimental animals, suggesting stimulation of both α and β adrenergic receptors. However, in vitro studies indicate that etilefrine has a much higher affinity for β1 (cardiac) than for β2 adrenoreceptors. Intravenous etilefrine increases the pulse rate, cardiac output, stroke volume, central venous pressure and mean arterial pressure of healthy individuals. Marked falls in pulse rate, cardiac output, stroke volume and peripheral bloodflow, accompanied by rises in mean arterial pressure, occur when etilefrine is infused after administration of intravenous propranolol 2,5 mg. These findings indicate that etilefrine has both β1 and α1 adrenergic effects in man. The French Health Products Agency concluded that etilefrine and heptaminol have an unfavourable harm-benefit balance, and also placed restrictions on the use of midodrine.

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.

Melperone is an antipsychotic drug which is used in Europe for the treatment of sleep disorders, agitation and confusion states. The exact mechanism of melperone action is unknown.

Zotepine is a potent antipsychotic and antidepressive drug, which was developed in Japan and used in many countries for the treatment of schizophrenia. Zotepine has high affinity to D2, 5-HT2A, 5-HT2C, 5-HT6, 5-HT7, alpha1A, H1, and D1 receptors at therapeutically relevant concentrations and has similar affinities to 5-HT1A, alpha2A, and M1 receptors at high concentrations. In human zotepine is metabolized to a major metabolite, norzotepine, which has profile similar to that of zotepine for important neurotransmitter receptors known to be responsible for zotepine antipsychotic activity.The drug is still available in Asia.

Moxisylyte, also known as thymoxamine, is a drug used in urology for the treatment of erectile dysfunction, also was studied, that this drug may be useful to treat ocular disorders such as diabetic retinopathy. It is an alpha1-adrenergic antagonist. Was developed for self-injection therapy in France and marketed in several European countries as Icavex. In the spring 2005 the manufacturer of Icavex decided to withdraw this drug from Europe market, presumable due to its low market shares.