Pimobendan (Vetmedin) use in heart disease/Cardiac drugs

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Josephine
Little Jo Wheek

Post   » Sun May 29, 2005 2:10 pm


Currently looks like pimobendan is available in Canada, the UK, and Australia, to name a few, but it's in clinical trials in the US. The info I found on the web suggests it's been available since 2000.

Cardiac (heart) drugs have many different categories and uses. The most commonly used in guinea pigs seem to be ACE-inhibitors like enalapril (Enacard), captopril (Capoten), lisinopril, or benazepril HCL (Fortekor, Lotensin). These drugs work by inhibiting an ezyme called angiotensin converting enzyme (hence the "ACE") which in turn ends up causing vasodilation. The end result is increased cardiac output (more blood volume pumped through body) and a lower general blood pressure.

Pimobendan (vetmedin) is in a different class of drugs, however, than ACE-inhibitors. It is in a class called calcium channel blockers. Some of these drugs have multiple effects and are in other cardiac drug categories as well. Other calcium channel blockers include amlodipine besylate (Norvasc), diltiazem HCL (Cardizem, Tiamate, Diltiazem, etc.), and verapamil HCL (Calan, Isoptin, etc.). These drugs are primarily antiarrhythmic drugs--that is to say they keep the heart beating regularly. One of the problems with heart disease is that the heart can beat faster (tachycardia) and/or irregularly (arrythmia) which creates many problems. These drugs primarily block calcium from having an effect on the muscles of the heart (the heart is basically composed of mainly muscle). This causes the heart to not contract like it would if it was trying to beat too fast. They can also effect electrical activity on the heart (which can pretty much slow heart rate, too). Another effect of inhibiting calcium can also cause some vasodilation which reduces blood pressure. Amlodipine is well known and used in cats for that specific reason.

One of the problems in treating heart disease is the type of heart problem. There are other cardiac drugs that are indicated for other diseases. Cardiac ultrasound is really the only way to tell which heart problem is causing the murmur (whether it is a certain valve or what). Some problems do well on treatment that is not necessarily the appropriate treatment for the problem due to the alleviation of clinical signs. For example my guinea pig, Antoine, had a murmur that affected his pulmonary valve. The disease was called pulmonic stenosis and the treatment is usually surgical. For multiple reasons, open heart surgery was not available nor indicated in his case. There is no other "cure," but due to his decreased heart output, he did well on ACE-inhibitors which raised the cardiac output.

Most guinea pigs are not completely worked-up and diagnosed as to the specific heart problem (sometimes due to lack of informed radiologists to ultrasound the heart). Thus, treatment is empirical, or based on clinical signs, a good DVM's expertise, and response to treatment.

I hope to post a few links on pimobendan and other drugs as they become available. Not addressed here are potential drug interactions (of which there are many) and doses--especially when used with other drugs. Using several drugs at once can increase the chance of adverse effects (like low blood pressure with cardiac drugs) and generally reduce the dose of each drug needed to achieve therapeutic effects. I have also not gone into diuretic drugs like furosemide (Lasix) which reduce tissue fluid left with poor heart function. That's for another thread ;)

If anyone has any clinical information as well as anectdotal info on these drugs, please post here to share!


Josephine
Little Jo Wheek

Post   » Sun May 29, 2005 2:23 pm


Oh, and I forgot to ask if it was stooopid enough for you guys. Most of you know more than the average layperson, so I take a lot for granted.

Josephine
Little Jo Wheek

Post   » Sun May 29, 2005 2:36 pm


Shoot, past my 10 minute edit time already!

I also meant to say something about the fact that pimobendan is listed as a Ca channel blocker as well as partially phosphodiesterase inhibiting. I already explained the Ca blocking. The phosphodiesterase is an enzyme that blocks vasodilation, so if you block it you allow vasodilation.

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SusieQ
Scrapbook Addict

Post   » Sun May 29, 2005 3:21 pm


I'm just interested in hearing (perhaps from Pinta since her heart pigs are on both?) when pimobendan is indicated in heart pigs vs Lotensin (Fortekor), or when it would be appropriate to use both.

I'd rather have all the information I can before I call my vet since she asks me to do the research anyway.

Currently my heart pigs are on once daily Lotensin only, and they seem to be okay, but if there's anything else that will help them I'd like to explore the possibilities.

Evangeline

Post   » Sun May 29, 2005 7:10 pm


Stoopid enough. Thanks a lot, Jo.

pinta

Post   » Fri Jun 03, 2005 2:07 am


I asked my vet again if it was okay for pigs to be on Fortekor and vetmedin and she said it was fine. Made a huge difference with Fanny. Fortekor alone wasn't doing it but the vetmedin brought her energy back up. I have Dom on it now as well and he is doing well. He's on fortekor, vetmedin, and amphogel(sp?)

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cavyhaven13

Post   » Mon Nov 14, 2005 6:26 am


Pimobendan was mentioned to me at my last vet visit. Now that it's available in the US, does anyone have any new information on it's use?

I have a 6 year old boar with a murmur, who has had 2 increases in his Enacard in the last 6 months and I'm looking for anything that might help him extend the quality of his life.

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Lynx
RESIST

Post   » Mon Nov 14, 2005 8:58 am


Does a search turn up anything on this drug? My memory is poor.

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cavyhaven13

Post   » Mon Nov 14, 2005 10:34 am


Yes, I did some searching on it with Google. It's the same basic information that is mentioned here. But I am curious how safe or effective it's use has been in guinea pigs. Some sites say that if there is a murmur, then it probably shouldn't be used. Some sites don't make that distinction. I have 2 pigs that don't have murmurs that are on Enacard, and 1 that does, Butters. Obviously, I'm concerned about Butters situation because of his recent medication change. The vet mentioned Pimobendan as a possible drug, but she wasn't sure about it's use in guinea pigs yet. I don't have enough medical background to easily understand some of the writings.

From my searching here, it sounds like Pinta has been using and has had good results. I guess I would like to hear more about it.

pinta

Post   » Mon Nov 14, 2005 5:32 pm


We're using it in Fanny daily and have used it in Bliss and Dom got it daily - no ill effects but none of these pigs were diagnosed with heart murmurs. All these pigs also got Fortekor daily or twice daily.

We had stopped using it in Fanny but her heart seemed to get worse as her hyperthryroidism progressed so we put her back on. She's pretty stable now. With her, weight is an indication of stability.

pinta

Post   » Thu Mar 30, 2006 9:51 pm


Since my last post both Fanny and Dom have passed on.

Rachel was on Fortekor alone but her mouth colours were still mauve after 10 days of Fortekor. We added in Vetmedin and she pinked up beautifully.

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Mum
I GAVE, dammit!

Post   » Thu Mar 30, 2006 10:00 pm


Lynx, can we make this a sticky, since this drug is mentioned so frequently but it's so hard to find any information about it?

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Lynx
RESIST

Post   » Thu Mar 30, 2006 10:23 pm


It would make more sense to move it to the Reference forum.

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Mum
I GAVE, dammit!

Post   » Thu Mar 30, 2006 10:24 pm


Perfect.

Josephine
Little Jo Wheek

Post   » Wed Jun 21, 2006 4:48 pm


I wanted to post that vets are now starting to use this drug more in the US in dogs and cats. One of the veterinary pharmacies is advertising compounding now. You have to be certain to ask for the drug name, not any brand names.

www.wedgewoodpharmacy.com for pimobendan compounding

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