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| Clinical data | |
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| Trade names | Vetmedin, others |
| AHFS/Drugs.com | International Drug Names |
| License data | |
| Routes of administration | By mouth |
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| Pharmacokinetic data | |
| Bioavailability | 60 to 65% |
| Eliminationhalf-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, orpimobendane), sold under the brand nameVetmedin among others, is a veterinary medication. It is a calcium sensitizer and a selective inhibitor ofphosphodiesterase 3 (PDE3) with positiveinotropic andvasodilator effects.
Pimobendan is used in the management ofheart failure in dogs, most commonly caused by myxomatous mitral valve disease (also previously known asendocardiosis), ordilated cardiomyopathy.[3] Research has shown that as a monotherapy, pimobendan increases survival time and improves quality of life in canine patients withcongestive heart failure secondary to mitral valve disease when compared withbenazepril, anACE inhibitor.[4] Under the brand nameAcardi, it is available for human use in Japan.[5] It is available as ageneric medication.[6]
Pimobendan isindicated 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 positiveinotrope, and its main function is to increase myocardial contractility. It sensitizes and increases the binding efficiency of cardiac troponin in themyofibril to the calcium ions that are already present in systole. In healthy hearts, it elevates oxygen and energy consumption to a level comparable to that achieved with dobutamine; however, in pathological hearts, this effect may not occur.[11][12] Pimobendan also causes peripheralvasodilation by inhibiting the function of phosphodiesterase 3 (PDE3). This results in decreased resistance to blood flow through systemic arterioles, which decreasesafterload (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 abioavailability 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 potentphosphodiesterase III inhibitor.[17] Thehalf-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.
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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) andCID: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).
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