Clinical data | |
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Trade names | Vetmedin, others |
AHFS/Drugs.com | International Drug Names |
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Routes of administration | By mouth |
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Pharmacokinetic data | |
Bioavailability | 60 to 65% |
Elimination half-life | 0.4 hours |
Excretion | In feces |
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CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.168.193 |
Chemical and physical data | |
Formula | C19H18N4O2 |
Molar mass | 334.379 g·mol−1 |
3D model (JSmol) | |
Chirality | Racemic mixture |
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Pimobendan (INN, or pimobendane), sold under the brand name Vetmedin among others, is a veterinary medication. It is a calcium sensitizer and a selective inhibitor of phosphodiesterase 3 (PDE3) with positive inotropic and vasodilator effects.
Pimobendan is used in the management of heart failure in dogs, most commonly caused by myxomatous mitral valve disease (also previously known as endocardiosis), or dilated cardiomyopathy. [3] Research has shown that as a monotherapy, pimobendan increases survival time and improves quality of life in canine patients with congestive heart failure secondary to mitral valve disease when compared with benazepril, an ACE inhibitor. [4] Under the brand name Acardi, it is available for human use in Japan. [5] It is available as a generic medication. [6]
Pimobendan is indicated for the management of the signs of mild, moderate, or severe congestive heart failure in dogs due to clinical myxomatous mitral valve disease (MMVD) or dilated cardiomyopathy (DCM); [1] [7] and for use with concurrent therapy for congestive heart failure (e.g.,furosemide, etc.) as appropriate on a case-by-case basis. [1] It is also indicated for the delay of onset of congestive heart failure in dogs with Stage B2 preclinical myxomatous mitral valve disease (2019 ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs). [2] [8] [9] [10]
Pimobendan is a positive inotrope, and its main function is to increase myocardial contractility. It sensitizes and increases the binding efficiency of cardiac troponin in the myofibril to the calcium ions that are already present in systole. In normal hearts it increases the consumption of oxygen and energy to the same degree as dobutamine but in diseased hearts it may not. [11] [12] Pimobendan also causes peripheral vasodilation by inhibiting the function of phosphodiesterase 3 (PDE3). This results in decreased resistance to blood flow through systemic arterioles, which decreases afterload (decreases the failing heart's workload) and reduces the amount of mitral regurgitation. [13] [14]
Pimobendan is absorbed rapidly when given via the oral route and has a bioavailability of 60–65%. [15] Food decreases the bioavailability of the aqueous solution although the effect on the tablet form is unknown. [16] It 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. [17] The half-life of pimobendan in the blood is 0.4 hours, and the half-life of its metabolite is two hours. Elimination is by excretion in the bile and then feces. Pimobendan is 90–95% bound to plasma proteins in circulation. This may have implications in patients with low blood protein levels (hypoproteinemia/hypoalbuminemia) and in patients that are on concurrent therapies that are also highly protein bound.
Pimobendan is often used in combination with three other drugs to palliate dogs with heart failure (pulmonary edema, pleural effusion, ascites). These are:
The reaction between p-anisoyl chloride [100-07-2] (1) and CID:20516917 (2) gives 4-[4-[(4-Methoxybenzoyl)amino]-3-nitrophenyl]-3-methyl-4-oxobutanoic acid, CID:20516902 (3). The reaction of this with hydrazine gives 5-methyl-6-[3-nitro-4-(4-methoxy-benzoylamino)-phenyl]-3-oxo-4,5-dihydro-2H-pyridazine [74149-73-8]. Catalytic hydrogenation reduces the nitro group giving [74149-74-9] (4). cyclization of the resulting ortho amino amide by means of a strong acid leads to the formation of the corresponding benzimidazole. There is thus obtained pimobendan (5).
A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE), thereby preventing the inactivation of the intracellular second messengers, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) by the respective PDE subtype(s). The ubiquitous presence of this enzyme means that non-specific inhibitors have a wide range of actions, the actions in the heart, and lungs being some of the first to find a therapeutic use.
Furosemide, sold under the brand name Lasix among others, is a loop diuretic medication used to treat edema due to heart failure, liver scarring, or kidney disease. Furosemide may also be used for the treatment of high blood pressure. It can be taken intravenously or orally. When given intravenously, furosemide typically takes effect within five minutes; when taken orally, it typically metabolizes within an hour.
Hydrochlorothiazide, sold under the brand name Hydrodiuril among others, is a diuretic medication used to treat hypertension and swelling due to fluid build-up. Other uses include treating diabetes insipidus and renal tubular acidosis and to decrease the risk of kidney stones in those with a high calcium level in the urine. Hydrochlorothiazide is taken by mouth and may be combined with other blood pressure medications as a single pill to increase effectiveness. Hydrochlorothiazide is a thiazide medication which inhibits reabsorption of sodium and chloride ions from the distal convoluted tubules of the kidneys, causing a natriuresis. This initially increases urine volume and lowers blood volume. It is believed to reduce peripheral vascular resistance.
Antihypertensives are a class of drugs that are used to treat hypertension. Antihypertensive therapy seeks to prevent the complications of high blood pressure, such as stroke, heart failure, kidney failure and myocardial infarction. Evidence suggests that reduction of the blood pressure by 5 mmHg can decrease the risk of stroke by 34% and of ischaemic heart disease by 21%, and can reduce the likelihood of dementia, heart failure, and mortality from cardiovascular disease. There are many classes of antihypertensives, which lower blood pressure by different means. Among the most important and most widely used medications are thiazide diuretics, calcium channel blockers, angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers or antagonists (ARBs), and beta blockers.
Amlodipine, sold under the brand name Norvasc among others, is a calcium channel blocker medication used to treat high blood pressure, coronary artery disease (CAD) and variant angina. It is taken orally.
Loop diuretics are pharmacological agents that primarily inhibit the Na-K-Cl cotransporter located on the luminal membrane of cells along the thick ascending limb of the loop of Henle. They are often used for the treatment of hypertension and edema secondary to congestive heart failure, liver cirrhosis, or chronic kidney disease. While thiazide diuretics are more effective in patients with normal kidney function, loop diuretics are more effective in patients with impaired kidney function.
Cyclic guanosine monophosphate-specific phosphodiesterase type 5 is an enzyme from the phosphodiesterase class. It is found in various tissues, most prominently the corpus cavernosum of the clitoris and of the penis as well as the retina. It has also been recently discovered to play a vital role in the cardiovascular system.
Cilostazol, sold under the brand name Pletal among others, is a medication used to help the symptoms of intermittent claudication in peripheral vascular disease. If no improvement is seen after 3 months, stopping the medication is reasonable. It may also be used to prevent stroke. It is taken by mouth.
Benazepril, sold under the brand name Lotensin among others, is a medication used to treat high blood pressure, heart failure, and diabetic kidney disease. It is a reasonable initial treatment for high blood pressure. It is taken by mouth. Versions are available as the combinations benazepril/hydrochlorothiazide and benazepril/amlodipine.
Valsartan, sold under the brand name Diovan among others, is a medication used to treat high blood pressure, heart failure, and diabetic kidney disease. It belongs to a class of medications referred to as angiotensin II receptor blockers (ARBs). It is a reasonable initial treatment for high blood pressure. It is taken by mouth.
Etacrynic acid (INN) or ethacrynic acid (USAN), trade name Edecrin, is a loop diuretic used to treat high blood pressure and the swelling caused by diseases like congestive heart failure, liver failure, and kidney failure. A con with ethacrynic acid compared to the other loop diuretic drugs such as furosemide is that it has a significantly steep dose-response curve, which means the drug's dosing is very important as small variance in dose can cause a significant difference in the biological response.
Hydralazine, sold under the brand name Apresoline among others, is a medication used to treat high blood pressure and heart failure. This includes high blood pressure in pregnancy and very high blood pressure resulting in symptoms. It has been found to be particularly useful in heart failure, together with isosorbide dinitrate, for treatment of people of African descent. It is given by mouth or by injection into a vein. Effects usually begin around 15 minutes and last up to six hours.
The health of dogs is a well studied area in veterinary medicine.
Torasemide, also known as torsemide, is a diuretic medication used to treat fluid overload due to heart failure, kidney disease, and liver disease. It is a less preferred treatment for high blood pressure. It is taken by mouth or by injection into a vein.
Amrinone, also known as inamrinone, and sold as Inocor, is a pyridine phosphodiesterase 3 inhibitor. It is a drug that may improve the prognosis in patients with congestive heart failure. Amrinone has been shown to increase the contractions initiated in the heart by high-gain calcium induced calcium release (CICR). The positive inotropic effect of amrinone is mediated by the selective enhancement of high-gain CICR, which contributes to the contraction of myocytes by phosphorylation through cAMP dependent protein kinase A (PKA) and Ca2+ calmodulin kinase pathways.
Deracoxib is a nonsteroidal anti-inflammatory drug (NSAID) of the coxib class, used in dogs to treat pain associated with osteoarthritis, or to prevent pain following orthopedic or dental surgery. It is available as beef-flavored tablets.
A PDE3 inhibitor is a drug which inhibits the action of the phosphodiesterase enzyme PDE3. They are used for the therapy of acute heart failure and cardiogenic shock.
Acute decompensated heart failure (ADHF) is a sudden worsening of the signs and symptoms of heart failure, which typically includes difficulty breathing (dyspnea), leg or feet swelling, and fatigue. ADHF is a common and potentially serious cause of acute respiratory distress. The condition is caused by severe congestion of multiple organs by fluid that is inadequately circulated by the failing heart. An attack of decompensation can be caused by underlying medical illness, such as myocardial infarction, an abnormal heart rhythm, infection, or thyroid disease.
Cardiotonic agents, also known as cardiac inotropes or stimulants, have a positive impact on the myocardium by enhancing its contractility. Unlike general inotropes, these agents exhibit a higher level of specificity as they selectively target the myocardium. They can be categorised into four distinct groups based on their unique mechanisms of action: cardiac glycosides, beta-adrenergic agonists, phosphodiesterase III inhibitors, and calcium sensitizers. It is important to note that certain medications, such as Milrinone and Digoxin, possess overlapping classifications due to their ability to engage multiple mechanisms of action. Their inotropic properties make cardiactonic agents critical in addressing inadequate perfusion, and acute heart failure conditions including cardiogenic shock, as well as for long-term management of heart failure. These conditions arise when the heart's ability to meet the body's needs is compromised.