Mecamylamine (Inversine), the first orally available antihypertensive agent, is now rarely used. Introduced as a therapeutic agent for the treatment of hypertension in the 1950s, mecamylamine was the first useful ganglionic blocking agent that was not a quarternary ammonium compound. Mecamylamine is indicated for the management of moderately severe to severe essential hypertension and in uncomplicated cases of malignant hypertension. Mecamylamine reduces blood pressure in both normotensive and hypertensive individuals. A small oral dosage often produces a smooth and predictable reduction of blood pressure. Although this antihypertensive effect is predominantly orthostatic, the supine blood pressure is also significantly reduced. Mecamylamine is a nicotinic parasympathetic ganglionic blocker. Mecamylamine administration produces several deleterious side-effects at therapeutically relevant doses. As such, mecamylamine’s use as an antihypertensive agent was phased out, except in severe hypertension. Mecamylamine easily traverses the blood-brain barrier to reach the central nervous system (CNS), where it acts as a nicotinic acetylcholine receptor (nAChR) antagonist, inhibiting all known nAChR subtypes. Since nAChRs play a major role in numerous physiological and pathological processes, it is not surprising that mecamylamine has been evaluated for its potential therapeutic effects in a wide variety of CNS disorders, including addiction.

Hydralazine is a direct-acting vasodilator that is used as an antihypertensive agent. Hydralazine works by relaxing blood vessels (arterioles more than venules) and increasing the supply of blood and oxygen to the heart while reducing its workload. It also functions as an antioxidant. It inhibits membrane-bound enzymes that form reactive oxygen species, such as superoxides. Excessive superoxide counteracts NO-induced vasodilation. Hydralazine is used for the treatment of essential hypertension, alone or as an adjunct. Also for the management of severe hypertension when the drug cannot be given orally or when blood pressure must be lowered immediately, congestive heart failure (in combination with cardiac glycosides and diuretics and/or with isosorbide dinitrate), and hypertension secondary to pre-eclampsia/eclampsia.

Pentaerythritol tetranitrate is an organic nitrate that has been used for the treatment of angina pectoris. Upon administration, the drug undergoes exstensive metabolism to NO which causes vasodilation and the relaxation of smooth muscle cells. The compound belongs to a familiy of explosive substances and may be used accordingly.

Apocynin, also known as acetovanillone, is a natural organic compound related to vanillin. It has been isolated from a variety of plant sources. Metabolites of apocynin are able to block the activity of NADPH oxidase, thus giving apocynin antioxidant and anti-inflammatory capabilities. Effects of apocynin on the concentration of reactive oxygen and nitrogen species in patients with asthma and chronic obstructive pulmonary disease were investigated in phase I clinical trials. In preclinical models, it was found that apocynin provides neuroprotective effects in models of stroke and Parkinson's disease.

Betanin (betanidin-5-O-beta-glucoside, Beetroot Red) is a red glycosidic food dye obtained from beets. Betanin is the most common betacyanin in the plant kingdom. According to the regulation on food additives betanin is permitted quantum satis as a natural red food colorant (E162). Moreover, betanin is used as colorant in cosmetics and pharmaceuticals. Recently, potential health benefits of betalains and betalain-rich foods (e.g. red beet, Opuntia sp.) have been discussed. Betanin is a scavenger of reactive oxygen species and exhibits gene-regulatory activity partly via nuclear factor (erythroid-derived 2)-like 2-(Nrf2) dependent signaling pathways. Betanin may induce phase II enzymes and antioxidant defense mechanisms. Furthermore, betanin possibly prevents LDL oxidation and DNA damage. Potential blood pressure lowering effects of red beet seem to be mainly mediated by dietary nitrate rather than by betanin per se.

(+)-Fadrozole (FAD-286) is an aldosterone synthase inhibitor. The drug was tested in vivo in preclinical models of hypertension, heart failure and was shown to reduce retinal neovascularization in rats with oxygen-induced retinopathy.

Pirinixic acid is a PPARα ligand that can affect atherogenesis by modulating hepatic lipid metabolism and by acting directly on vascular tissue. PPARα activation is generally assumed to be the primary means by which Pirinixic acid produces its biological effects. Nevertheless, there is increasing evidence to suggest that Pirinixic acid is also capable of affecting cellular processes directly. It is under experimental investigation for prevention of severe cardiac dysfunction, cardiomyopathy and heart failure as a result of lipid accumulation within cardiac myocytes. Treatment is primarily aimed at individuals with an adipose triglyceride lipase (ATGL) enzyme deficiency or mutation. For example, cardiac contractility was improved by treating ATGL(-/-) mice with the Pirinixic acid.

Gomisin A (BESIGOMSIN/GA) one of the major dibenzocyclooctadiene lignans isolated from Schisandra chinensis Baill, has proved to possess a variety of pharmacological effects. It has been found to promote hepatocyte growth factor, limit lipid peroxidation, and inhibit apoptosis in acute hepatic injury animal models. Besigomsine also acts as an anti-inflammatory by preventing the release of arachidonic acid in macrophages in vitro. Laboratory evidence suggests that Besigomsine may have anticarcinogenic effects. Chronic administration of Gomisin A had an antihypertensive effect in AngII-induced hypertensive mice. Gomisin A may exert neuroprotective effects by attenuating the microglia-mediated neuroinflammatory response via inhibiting the TLR4-mediated NF-κB and MAPKs signaling pathways. Also it induces marked protective effects against hepatic and renal injury induced by CCl(4) exposure through differential regulation of the MAPK signal transduction pathway.

Teprotide, a nonapeptide isolated from the venom of a Brazilian pit viper, Bothrops jararaca, was the first angiotensin converting enzyme (ACE) inhibitor to be discovered and tested. It was found to be an effective, non-toxic antihypertensive agent as well as an afterload-reducing agent for patients with congestive heart failure (CHF). The primary activity of teprotide resulted from blockade of the angiotensin I converting enzyme--the pivotal step in the renin-angiotensin-aldosterone system (RAAS), and consequent reductions in angiotensin II levels. There was limited clinical testing for teprotide because of: its scarcity; the need for parenteral administration; and the subsequent discovery and synthesis of captopril, the first orally active angiotensin converting enzyme inhibitor.

Compound M24 is a selective angiotensin II AT2 receptor agonist with a Ki value of 0.4 nM for the AT2 receptor. Compound enhances in vivo duodenal alkaline secretion in Sprague-Dawley rats, and lowers the mean arterial blood pressure in anesthetized, spontaneously hypertensive rats. In a mouse model of atherosclerosis, plaque size and stability were improved in ApoE‐/‐ mice treated with M24. Treatment with M24 resulted in decrease in scar size and reduction in markers of inflammation in a rat model of myocardial infaction.