Pimobendan (INN, or pimobendane; tradenames Vetmedin, Acardi, and Heartmedin) is a veterinary medication. Under the trade name Acardi, it is available for human use in Japan. Usually, this medicine is used to treat acute heart failure and chronic heart failure (mild to moderate in severity). By increasing the calcium ion sensitivity to protein regulating myocardial contraction and also by inhibiting phosphodiesterase (PDE-III) activity, this medicine dilates the blood vessels and improves the symptoms of heart failure such as shortness of breath and difficulty in breathing. Pimobendan is metabolized into an active metabolite (desmethylpimobendan) by the liver. The parent compound, pimobendan, is a potent calcium sensitizer while desmethylpimobendan is a more potent phosphodiesterase III inhibitor. Pimobendan is 90–95% bound to plasma proteins in circulation. This may have implications in patients suffering from low blood protein levels (hypoproteinemia/hypoalbuminemia) and in patients that are on concurrent therapies that are also highly protein bound.

Sitaxentan (TBC11251, trade name Thelin) is a potent and selective Endothelin A receptor antagonist. Sitaxentan was under development by Encysive Pharmaceuticals (now Pfizer) for use in the treatment of pulmonary hypertension, congestive heart failure and asthma. It was launched in the major markets of the European Union (EU) under name Thelin for the treatment of pulmonary arterial hypertension. In December 2010, Pfizer discontinued clinical trials of sitaxentan worldwide and initiated voluntary product withdrawal from markets where it is approved due to life-threatening idiosyncratic risk of liver injury.

Xamoterol (ICI 118,587) is a partial agonist of beta1-adrenoceptors. Xamoterol acts on the cardiac beta 1-adrenergic receptor, modifies the response of the heart to variations in sympathetic activity. At rest, it produces modest improvements in cardiac contractility, relaxation, and filling without increase in myocardial oxygen demand. The improvements are maintained during exercise although the attendant tachycardia is attenuated. The beneficial effects of xamoterol on both systolic and diastolic function suggested that it would be effective in patients with mild-to-moderate heart failure, and this was demonstrated in small placebo-controlled studies where effort tolerance and symptoms were improved. Xamoterol produced improvements in exercise capacity, clinical signs, symptoms and quality of life with a low incidence of adverse experiences. Xamoterol is effective as monotherapy in heart failure.

Toborinone is an inotropic agent. Positive inotropic effects are produced by Phosphodiesterase inhibition with resulting increase in cAMP and intracellular calcium levels. There is also marked venous and arterial vasodilating properties. With regards to human administration, toborinone is generally well-tolerated, though there are no available data regarding long-term tolerability and side effects. Toborinone can be combined with angiotensin-converting-enzyme inhibitors, nitrates and diuretics for the treatment of heart failure.

Rutaecarpine is an indolopyridoquinazolinone alkaloid isolated from Evodia rutaecarpa and related herbs, first isolated by Asahina and Kashiwaki. Among the active components of evodia are quinolone and indoloquinazoline alkaloids, such as evodiamine and rutaecarpine. A significant portion of the analgesic effects of evodia is attributed to these alkaloids. Rutaecarpine has also been shown to have anti-inflammatory action that is related to inhibition of COX-2, as well as other mechanisms. Evodia rutaecarpa ('Wu-Chu-Yu') remains the most popular and multi-purpose herb traditionally used in China for treatment of headache, abdominal pain, postpartum hemorrhage, dysentery and amenorrhea. Rutaecarpine is one of the main active component isolated from 'Wu-Chu-Yu'. Rutaecarpine has been shown to have cardiovascular biological effects such as inotropic and chronotropic, vasorelaxant, anti-platelet aggregation and anti-inflammatory effects. Furthermore, rutaecarpine has the potential for use as an anti-atherosclerosis agent with a novel mechanism. Rutaecarpine prevents hypoxia-reoxygenation-induced myocardial cell apoptosis via inhibition of NADPH oxidases. Also was shown, that rutaecarpine could be effective in preventing the growth of a variety of cancer cells, including downregulating the estrogen receptor of breast cancer.

Tasosartan is a long-acting angiotensin II (AngII) receptor blocker. Tasosartan is infrequently in the treatment of hypertension and heart failure. The manufacturer withdrew it from FDA review after phase III clinical trials showed elevated transaminases. Tasosartan blocks the renin-angiotensin-aldosterone system (RAAS) at the level of the AT1 receptor that mediates most, if not all, of the important actions of Ang II. Tasosartan binds reversibly to the AT1 receptors in vascular smooth muscle and the adrenal gland. As angiotensin II is a vasoconstrictor, which also stimulates the synthesis and release of aldosterone, blockage of its effects results in decreases in systemic vascular resistance.

Bucindolol is a third-generation, non-selective β-adrenergic receptor blocker, that acts on both β-1 and β-2 receptors. Bucindolol’s additional α-1 antagonistic activity contributes to its mild vasodilator effect. It was rejected by the FDA for the heart failure, because of the unreviewed submissions deal with comparative effectiveness, clinical pharmacology, some aspects of pharmacogenetic data, and toxicology/metabolism. In addition, bucindolol is in the phase II of clinical trial for the treatment of atrial fibrillation.

Cyclopenthiazide is a thiazide diuretic. It inhibits the Na+-Cl− symporter in the distal convoluted tubule of the kidney. Cyclopenthiazide is used for the treatment of edema, including that associated with heart failure, and for the treatment of hypertension.

Dopexamine hydrochloride is a synthetic catecholamine, structurally related to dopamine, with marked intrinsic agonist activity at beta 2-adrenoceptors, lesser agonist activity at dopamine DA1- and DA2-receptors and beta 1-adrenoceptors, and an inhibitory action on the neuronal catecholamine uptake mechanism. The drug is administered by intravenous infusion, and is characterized by a rapid onset and short duration of action. Dopexamine is being tested as a treatment for heart failure and sepsis.

Omapatrilat is an antihypertensive agent that inhibits both neprilysin (neutral endopeptidase, NEP) and angiotensin-converting enzyme (ACE). The drug was developed for possible use in heart failure and hypertension, but was not approved by the FDA due to angioedema safety concerns.