- Pimobendan
Drugbox
IUPAC_name = 6- [2-(4-methoxyphenyl)-1"H"-benzimidazol-5-yl] -5-methyl-4,5-dihydropyridazin-3(2"H")-one
CAS_number = 74150-27-9
CAS_supplemental =
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PubChem = 4823
DrugBank =
chemical_formula =
C=19 | H=18 | N=4 | O=2
molecular_weight = 334.37 g/mol
smiles = CC1CC(=O)NN=C1C2=CC3=C(C=C2)N=C(N3)C4=CC=C(C=C4)OC
bioavailability = 60 to 65%
protein_bound =
metabolism =
elimination_half-life = 0.4 hours
excretion = In feces
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legal_status = Rx-only
routes_of_administration = OralPimobendan (INN, manufactured by
Boehringer Ingelheim under the trade names Vetmedin and Acardi), also known as pimobendane, is a calcium sensitizer with positiveinotropic andvasodilator effects. It is also a selective inhibitor ofphosphodiesterase III (PDE3 ).Pimobendan is used in the management of
heart failure in dogs, most commonly caused by myxomatous mitral valve disease (also known asendocardiosis ), ordilated cardiomyopathy . [cite journal |author=Gordon SG, Miller MW, Saunders AB |title=Pimobendan in heart failure therapy—a silver bullet? |journal=J Am Anim Hosp Assoc |volume=42 |issue=2 |pages=90–3 |year=2006 |pmid=16527909 |doi= |url=http://www.jaaha.org/cgi/pmidlookup?view=long&pmid=16527909] Research has shown that pimobendan increases survival time and improves quality of life in patients withcongestive heart failure when compared withbenazepril , an angiotensin-converting-enzyme (ACE) inhibitor. [cite journal |author=Häggström J, Boswood A, O'Grady M, "et al" |title=Effect of Pimobendan or Benazepril Hydrochloride on Survival Times in Dogs with Congestive Heart Failure Caused by Naturally Occurring Myxomatous Mitral Valve Disease: The QUEST Study |journal=J. Vet. Intern. Med. |volume= |issue= |pages= |year=2008 |month=July |pmid=18638016 |doi=10.1111/j.1939-1676.2008.0150.x |url=] It is also available for human use inJapan , under the trade name Acardi. [cite web |url=http://www.rad-ar.or.jp/siori/english/kekka.cgi?n=54 |title=Kusuri-no-Shiori Drug Information Sheet |date=April 2005 |publisher=RAD-AR Council, Japan |accessdate=2008-08-06]Mechanism of action
Pimobendan is a positive
inotrope . It sensitizes and increase the binding efficency of cardiacmyofibril to the calcium ions that are already present without increasing the consumption of oxygen and energy.Pimobendan also causes peripheralvasodilation by inhibiting the function of phosphodiesterase III. This results in decreased pressure, translating into smaller cardiac preload andafterload (decreases the failing heart's workload).Pharmacokinetics
Pimobendan is absorbed rapidly when given via the oral route and has a
bioavailability of 60-65%. It is metabolized into its active form by theliver . Thehalf-life of pimobendan in the blood is 0.4 hours and the half-life of its metabolite is 2 hours. Elimination is by excretion in the bile and then, faeces. Pimobendan is 90–95% bound to plasma proteins in circulation. This has implications in patients suffering from low blood protein levels (hypoproteinemia /hypoalbuminemia ) and with patients that are on concurrent therapies that are also highly protein bound.Combinations
Pimobendan is often used in combination with three other drugs to palliate dogs with heart disease and reduce clinical signs of disease. These are:
*Furosemide , a diuretic, to reduce pulmonary oedema. This can be given intravenously if the animal is in respiratory distress (6-8mg/kg), and then titrated down to the minimum dose required orally.
*Spironolactone , analdosterone antagonist . This has two actions, firstly, as apotassium-sparing diuretic , although its diuretic properties are small compared with those of furosemide. Secondly, it reduces aldosterone-mediated myocardial remodelling and fibrosis, slowing the progression of heart disease.
*AnACE inhibitor , oftenenalapril (trade name Enacard) orbenazepril (Fortekor). These drugs inhibit the action ofangiotensin-converting enzyme , producing a balanced vasodilation, along with other favourable effects.Other drugs may also be used as required to manage certain
arrhythmias that are often associated with heart disease.ee also
*
Levosimendan References
Further reading
*cite journal |author=Lee JA, Allen DG |title=Calcium sensitisers |journal=BMJ |volume=300 |issue=6724 |pages=551–2 |year=1990 |month=March |pmid=2108746 |pmc=1662365
External links
*Vetmedin website ( [http://www.vetmedin.co.uk UK] and [http://www.vetmedin.com.au Australia] )
*Website about the QUEST study (reference 2) (http://www.questtrial.com)
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