Vidalta Tablets for cats

[Desley (booktigger)]

Carol, if you look on the link I provided, Vidalta is only produced in 10mg and 15mg tablets, and it says that if you need a lower dose, then a different medication should be used, not to split them. 10mg as a starting dose is only for if they are only vaguely hypert (although Tino was started on 10mg as he had a reaction to the 2.5mg Felimazole).

[Gill (sneakiefeline)]

Sometimes a shorter but happier life for our cats is best for them, but this has to be decided fore each cat by its ownere.

I would certainly speak to the vet even if its to say that you have taken the cat off the meds 

[jersey girl]

Hi many thanks for all the info, Jasper eating alittle and still sleeps alot but much happier, he was only on the drug for about a month so hope the affects arn't too much, he is so much better. Wow this is great being able to talk to someone about the drug

Thx

J


Inhibiting the hormone production (i.e inhibiting the production of thyroxine)  IS controlling excessive production Desley, its just another way of wording it.  Vidalta is carbimazole and it is metabolised to methimazole in the body.  It is the methimazole that is the active drug.  If you google metabolism of carbimazole you will get lots of references, this is just one of them

"Carbimazole, a thionamide, is a pro-drug which undergoes rapid and virtually complete metabolism to the active metabolite, thiamazole, also known as Methimazole. The method of action is believed to be inhibition of the organification of iodide and the coupling of iodothyronine residues which in turn suppress the synthesis of thyroid hormones."

The advantage of giving methimazole id that you know exactly how much you are giving.  The disadvantage is that it tastes absolutely foul and which is why the manufacturers put a sugar coating on it.  It may have a higher incidence of GI side effects such as vomiting but imn my experience Carbimazole also causes this.
The advantage of giving carbimazole is that it doesn't taste and can therefore be easier to administer to an animal.  However, since it has to be metabolised before it has any activity it could be less effective in the presence of lliver problems and there are reports (in humans) thats its absorption is more erratic than that of methimazole.

Chemistry aside, I still believe that the suggested dosing of Vidalta is WAY TOO HIGH but then I am one of those unfortunate people whose cat nearly died from a high starting dose of carbimazole (5 mg twice daily in Tiny's case).  I am a firm believer in starting low and working up to a therapeutic level.  That is by far the best way to control side effects of a drug that has to be taken for life.  I also belive that in the case of hyperthyroidism it is better to control it gradually rather than rapidly.  Although high thyroid levels are a very bad thing, the body does get used to them (in the same way that a drug addict gets used to heroin) and sudden withdrawal can have produce very nasty effects (a bit like the drug addict's cold turkey).  Its not unknown for sudden correction of hyperthyroidism, especially in the elderly (be it human or animal) to result in a stroke when the body's systems suddenly slow down.
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[CarolM (Wendolene)]

Thx for all your messages, Jasper purred the first time today, I could nearly cry just to know that he is happier is all I want.

I know that he will not be with us for ever, but just want his last few years if we get that long with him to be the best it can.

I will be phoning the vets to let them know the effect that this drug has had on Jasper and see what he says!!

Watch this space.

I would definitely ask about re-starting treatment on a lower dosage.  You don't mention Jasper being sick on the Vidalta so it sounds as though he actually tolerated it quite well - just had too much of it.  The Data Sheet for Vidalta says that you should not break or crush the tablets (they are a controlled-release formulation) but I know from someone who has contacted the manufacturers to ask about this that the tablets can be split in order to give a smaller dosage. The carbimazole and excipients are mixed evenly throughout the tablet so splitting it into say 2 or 4 pieces gives 2 or 4 even dosages and it also retains its controlled release properties.  [It shouldn't be crushed though because that would cause all the of carbimazole to be released at the same time instead of gradually over 24 hours].  Alternatively your vet could prescribe the 2.5 mg Felimazole tablet.  Do please persevere with treatment because, as others have said, untreated hyperthyroidism will shorten Jasper's lifespan.

[Janeyk]

They actually do slightly different things, Felimazole controls the excessive production, Vidalta inhibits the hormone production.

Inhibiting the hormone production (i.e inhibiting the production of thyroxine)  IS controlling excessive production Desley, its just another way of wording it.  Vidalta is carbimazole and it is metabolised to methimazole in the body.  It is the methimazole that is the active drug.  If you google metabolism of carbimazole you will get lots of references, this is just one of them

"Carbimazole, a thionamide, is a pro-drug which undergoes rapid and virtually complete metabolism to the active metabolite, thiamazole, also known as Methimazole. The method of action is believed to be inhibition of the organification of iodide and the coupling of iodothyronine residues which in turn suppress the synthesis of thyroid hormones."

The advantage of giving methimazole id that you know exactly how much you are giving.  The disadvantage is that it tastes absolutely foul and which is why the manufacturers put a sugar coating on it.  It may have a higher incidence of GI side effects such as vomiting but imn my experience Carbimazole also causes this.
The advantage of giving carbimazole is that it doesn't taste and can therefore be easier to administer to an animal.  However, since it has to be metabolised before it has any activity it could be less effective in the presence of lliver problems and there are reports (in humans) thats its absorption is more erratic than that of methimazole.

Chemistry aside, I still believe that the suggested dosing of Vidalta is WAY TOO HIGH but then I am one of those unfortunate people whose cat nearly died from a high starting dose of carbimazole (5 mg twice daily in Tiny's case).  I am a firm believer in starting low and working up to a therapeutic level.  That is by far the best way to control side effects of a drug that has to be taken for life.  I also belive that in the case of hyperthyroidism it is better to control it gradually rather than rapidly.  Although high thyroid levels are a very bad thing, the body does get used to them (in the same way that a drug addict gets used to heroin) and sudden withdrawal can have produce very nasty effects (a bit like the drug addict's cold turkey).  Its not unknown for sudden correction of hyperthyroidism, especially in the elderly (be it human or animal) to result in a stroke when the body's systems suddenly slow down.

That's right re wording Carol, I took Carbimazole myself and they are strong.  My levels were very high so my GP started me on a high dose and gradually reduced them to 10mg whereas my 2 cats, who had it at the same time were on 5mg throughout.

[Susanne (urbantigers)]

I don't kow anything about vidalta and I wouldn't like to jump to conclusions about your vet, but did you not contact your vet when Jasper reacted the way he did?  Even if your vet didn't specifically request checks following the introdution of the drug, I would have been straight on the phone if my cat had been lethargic and not eating.  I agree with Desley in that stopping meds should be done under veterinary consultation.  If your vet has not shown any interest in how Jasper responded to the vidalta, or you just don't have confidence in your vet, then I would find a new one asap.  Any drug can have side effects and it's often a case of balancing those against the potential benefits.  It may just be that it isn't the right drug for Jasper. 

What condition(s) does Jasper have?  I think for Jasper's sake, you should try to find a new vet.  There may be something else that can help him.

[CarolM (Wendolene)]

They actually do slightly different things, Felimazole controls the excessive production, Vidalta inhibits the hormone production.

Inhibiting the hormone production (i.e inhibiting the production of thyroxine)  IS controlling excessive production Desley, its just another way of wording it.  Vidalta is carbimazole and it is metabolised to methimazole in the body.  It is the methimazole that is the active drug.  If you google metabolism of carbimazole you will get lots of references, this is just one of them

"Carbimazole, a thionamide, is a pro-drug which undergoes rapid and virtually complete metabolism to the active metabolite, thiamazole, also known as Methimazole. The method of action is believed to be inhibition of the organification of iodide and the coupling of iodothyronine residues which in turn suppress the synthesis of thyroid hormones."

The advantage of giving methimazole id that you know exactly how much you are giving.  The disadvantage is that it tastes absolutely foul and which is why the manufacturers put a sugar coating on it.  It may have a higher incidence of GI side effects such as vomiting but imn my experience Carbimazole also causes this.
The advantage of giving carbimazole is that it doesn't taste and can therefore be easier to administer to an animal.  However, since it has to be metabolised before it has any activity it could be less effective in the presence of lliver problems and there are reports (in humans) thats its absorption is more erratic than that of methimazole.

Chemistry aside, I still believe that the suggested dosing of Vidalta is WAY TOO HIGH but then I am one of those unfortunate people whose cat nearly died from a high starting dose of carbimazole (5 mg twice daily in Tiny's case).  I am a firm believer in starting low and working up to a therapeutic level.  That is by far the best way to control side effects of a drug that has to be taken for life.  I also belive that in the case of hyperthyroidism it is better to control it gradually rather than rapidly.  Although high thyroid levels are a very bad thing, the body does get used to them (in the same way that a drug addict gets used to heroin) and sudden withdrawal can have produce very nasty effects (a bit like the drug addict's cold turkey).  Its not unknown for sudden correction of hyperthyroidism, especially in the elderly (be it human or animal) to result in a stroke when the body's systems suddenly slow down.

[Desley (booktigger)]

According to the NOAH compendium, 15mg of Vidalta is the starting dose, and the maintenance dose is 10mg. Checking it again, Vidalta only comes in 10mg and 15mg, unlike Felimazole, which comes in 2.5mg and 5mg. They actually do slightly different things, Felimazole controls the excessive production, Vidalta inhibits the hormone production.

http://www.noahcompendium.co.uk/Intervet_Schering-Plough/Vidalta_10_mg_tablets_for_cats_and_Vidalta_15_mg_tablets_for_cats/-47186.html

Jerseygirl - untreated hyper-t reduces their lifespan to months, as that is the dilemma I have with my hyper-t cat, the body simply cant sustain the high levels of the hormone and the pressure it puts on all their organs.

[jersey girl]

Thx for all your messages, Jasper purred the first time today, I could nearly cry just to know that he is happier is all I want.

I know that he will not be with us for ever, but just want his last few years if we get that long with him to be the best it can.

I will be phoning the vets to let them know the effect that this drug has had on Jasper and see what he says!!

Watch this space.

[CarolM (Wendolene)]

10mg doseage of Vidalta a day is very high and it's simply unacceptable not to have frequent follow up blood tests when initially prescribing it. ............ As I understand it, the doseage should start very low (more like 2.5mg or even lower) and increase slowly as required with regular blood tests initially after 7 to 10 days.  I also understand vets regularly start the doseage too high.  It's worrying.  . 

That is absolutely right.  I just can't understand why there is such a high dose tablet available for cats.  Going back about 10 years, there were NO products licensed for use in animals for the treatment of Hyper-T in the UK.  That doesn't mean there were no treatments, it just means that the product used was licensed for use in humans but not in animals.  That product was carbimazole (trade name Neo-Mercazole) and the tablet strength was 5 mg.  In the US they didn't use carbimazole but used methimazole (trade name Tapazole) which was also a 5 mg tablet.  Carbimazole is metabolised to methimazole in the body so both treatments are essentially the same thing. Vets in both countries started cats on a dose of one 5 mg tablet twice a day (from memory 5 mg carbimazole is equivalent to about 4.2 mg methimazole).  Some cats tolerate this starting dose well but a lot don't.  A 2.5 mg twice daily starting dose (or even less) has a much better chance of success.  When they did eventually get around to licensing products for use in cats in the UK they came up with Felimazole 5 mg tablets (the Trade name for methimazole) and then added a 2.5 mg tablet which takes account of the fact that some cats need a smaller dose.  How they came up with a 10 mg tablet of Vidlata (which is carbimazole) I just can't imagine and to start a cat on this dose seems criminal.

Jersey girl you did the right thing stopping the tablets but don't think that your beloved Jasper is untreatable.  With a MUCH smaller starting dose (of either carbimazole or felimazole) he could respond well.

Edited becausw I mixed up my Trade names and chemical names - Felimazole is the trade name for methimazole.

[Rosella moggy]

10mg doseage of Vidalta a day is very high and it's simply unacceptable not to have frequent follow up blood tests when initially prescribing it.  I went on to HyperT site recommended by a Purrs member last year for our Tom RIP after Tom experienced side effects on his liver from HyperT meds.  Sorry I'm at work so don't know site offhand.  As I understand it, the doseage should start very low (more like 2.5mg or even lower) and increase slowly as required with regular blood tests initially after 7 to 10 days.  I also understand vets regularly start the doseage too high.  It's worrying.  I will always google prescribed drugs now. 

Obviously Jersey Girl, your cat needs proper veterinary treatment if he is HyperT but I would try a different vet. 

[Desley (booktigger)]

I would be speaking to your vet urgently, stopping meds isn't somethign that should just be done without consultation. Like all meds, Vidalta has a risk of side effects, but not all cats will suffer with it and as Gillian said, it might just be he needs a different dose, or Felimazole instead to control his hyper-t. After a month, he will be due bloods anyway to check things out.

[clarenmax]

When Max was first prescribed Vidalta, we were up at the surgery every few weeks to check his levels, we're due again next week to check if the 1/2 tablet daily is the correct amount for him.

Thanks for the warning though, and I hope you manage to find a workable solution for Jasper 

[Gillian Harvey]

It sounds like the dose just needs adjusting. A follow up blood test is usually recommended after about 3 weeks of starting a drug for hyperthyroidism, just to check T4 levels again and make sure its within the right range or hasnt gone too low. Its not a good idea to just stop giving the drug, as untreated hyperT can adversely affect many organs in the body, epecially the heart. I'd have a word with your vet about blood testing Jasper again to check his T4 levels and then the dosage can be adjusted accordingly, or your vet may suggest a different drug.

[dabs]

http://www.intervet.co.uk/Products_Public/Vidalta/090_Product_Datasheet.asp

Found the data sheet for this drug as I have not heard of it before. It warns of decreased appetite and lethargy, another reason why I always look up what my vet prescribes my feline friends! 

I am sorry your cat had to go thru this and even more surprising that the vet dd not ask for follow up checks. My vet reckons that frequent checks are a legal must.

Can you not complain to the practice?

[jersey girl]

Hi everyone,

Im new to this sight but did not want to leave without telling you all about Vidalta tables, or should I say what the vet omits to tell you about this drug.

My gorgeous boy Jasper who is 18 1/2 yrs old, has not been eating property for over a week, infact he didn't eat more than a mouthfull of food but drank and slept.

How he has survived is quite incredible. He was prescribed Vidalta 10mg about a month ago and has been on this daily, but each day he has been getting more and more sleepy finally not eating at all. Three days ago I decided to stop giving him these tablets and you would not believe how he has changed. He even managed to go to the toilet outside in the garden which he has not done for about a month. I thought that he was going to have to be put to sleep but now he is eating and although still not opened up his bowels fully ,I'm sure that it won't be too long. Please before giving this tablet to your cat ensure that it is fully monitored as no checks by the vets have been made or asked to be made since he was prescribed to go on this drug. The difference is amazing and at his age I would rather have him back to himself even if abit senile and noisy than completely dopey all day.

Hopefully he will live on for many more months.

I have had him since he was 6 mths old and will be so upset when he finally leaves me.

Good luck with this drug!!!!!