Methimazole and Lack of Appetite

[GandalfTGray]

Hello. I’m new here but I’ve learned a lot lurking on this site over the years! I finally registered because my cat Ed (age 12) was recently diagnosed with hyperthyroidism. I’d suspected it, as he had all of the symptoms, then his blood work came back with a total T4 of 4.8.

We ordered methimazole compounded into chewable treats, 2.5mg each. Started him out on 2.5 once/day for a week, he seemed ok with that, then upped to twice/day for a total of 5mg. After five days on 5mg, he went what I assume was hyPOthyroid. Lost his appetite, spent a whole day vomiting the contents of his stomach, and was lethargic. We stopped the methimazole (I keep wanting to shorten it as “meth,” but that’s not right! Heh) for several days, he received fluids and an injection of Cerenia, and recovered.

After discussing with the vet and reading several threads here, we started him back at 2.5mg total per day, cutting his treats into two 1.25mg portions. After a week of that, he’s having appetite problems again! This time, no vomiting or lethargy. It’s more like being extremely picky, and I have to pull out all the tricks to get him to finish a meal. I don’t know what to do at this point. He needs to eat and get weight back on. I don’t know if I can cut his dose down any further and have it be effective. I don’t know if ANY of the dosing he’s taken so far has been effective, because I haven’t been able to keep him on the meds long enough to get a blood draw.

My long term goal is to stabilize him enough so that he can receive the I-131 treatment.
Any advice?

 

[FeebysOwner]

You might try the transdermal form and see if that helps with the stomach/inappetence issues.

 

[GandalfTGray]

You might try the transdermal form and see if that helps with the stomach/inappetence issues.

I'd love to hear more from people who use the transdermal, and its effectiveness and side effcts. My vet is reluctant to prescribe it because he thinks the dosing isn't as accurate.

 

[FeebysOwner]

I haven't used it, so I can't say from any personal experience. I do know that between doses of Mirataz (appetite stimulant) for Feeby, I need to clean her ears out because of a residue build up that can make an upcoming dose less effective. I suppose that would hold true of any of the transdermals. Here is a link to previous threads regarding the use of transdermal Methimazole, and it does seem like there might have been some issues with certain cats.
Search Results for Query: transdermal methimazole | TheCatSite

 

[Twylasmom]

I'd love to hear more from people who use the transdermal, and its effectiveness and side effcts. My vet is reluctant to prescribe it because he thinks the dosing isn't as accurate.

The dosing may be somewhat less accurate, but the advantage is it lessens the chance of gastrointestinal side effects so you would have a better chance of dosing your cat consistently. Seems like a fair trade off. I used transdermal with a previous cat and it worked fine with no noticeable side effects. Still need to monitor bloodwork and adjust dosage as needed. My current cat was pushed into a hypothyroid state by oral methimazole. After 6 weeks on two progressively lower doses she was still hypo, so is now off it for a month and will then start back on a much lower dose once we get a new baseline T4.

 

[SundaesPerson]

We tried the chewable treats for Sundae and not only did she not like them, but she also had major tummy troubles from it. As Twylasmom said, the dosing is somewhat less accurate, but it has worked wonders for my girl. We haven’t had any GI issues since switching to the transdermal.

 

[Antonio65]

Hi GandalfTGray , welcome to TCS.

My fist question is why you upped the methimazole treat from 2.5 m to 5 mg a day.
Actually, the 2.5 mg a day is the max that it is usually advised to administer. The Hyperthyroid cats community agrees that 1.25 mg twice a day is what works better in most cases, and sometimes that dose can be further reduced.
Methimazole is known for its several (and sometimes bad) side effects, a few of them are irreversible.

My cat started out with 1.25 mg twice a day (possibly at the same time of the day, with the two doses equally spaced), but later on she was put on a much lower dose, we went down to .625 mg a day.
The first medication was pills, but we soon switched to the transdermal gel when I noticed that my cat was having some GI issues.

Yes, the transdermal gel is less accurate, but it's easier to administer and it can be dosed to a much lower dosage, as proved by my 0.625 mg twice a day.
We were on that gel for a few months, then my cat was accepted at the I-131 facility and was successfully treated.

 

[GandalfTGray]

We tried the chewable treats for Sundae and not only did she not like them, but she also had major tummy troubles from it. As Twylasmom said, the dosing is somewhat less accurate, but it has worked wonders for my girl. We haven’t had any GI issues since switching to the transdermal.

Thanks

 

[GandalfTGray]

Hi GandalfTGray , welcome to TCS.

My fist question is why you upped the methimazole treat from 2.5 m to 5 mg a day.
Actually, the 2.5 mg a day is the max that it is usually advised to administer.

That was what the vet prescribed. I see that you are in Italy? In the US from what I have read, 2.5 - 5 mg seems to be the standard operating procedure for vets.

 

[Antonio65]

Yes GandalfTGray , I am in Italy.
When I first ventured on this new path with my cat with HT, I subscribed to a group where a few experts guide the community in what may seem a nightmare.
They are not doctors or vets, but it seems they have lots of experience. They are all based in the US, so I think the 1.25 mg twice a day may be a standard there too?

Many users go there and say their vets had them start out with a 2.5 mg twice a day, but some of them report side efects, especially about lack of appetite and GI issues.
It issaid tha tit is much better to start out on a low dose (1.25 mg) and then adjust to a higher dose if it's the case, rather than the opposite, because the damages of the drug may not be reversible.

My cat started with a 1.25 mg twice a day (pills*), then we switched to the gel a couple of months later, as it was much easier to give different dosage by simply applying more or less gel, rather than fiddling with a pill to be cut in weird fractions.

(*) the pills were methimazole for human use, 5 mg each. I asked the pharmacist to professionally cut them in four parts.

 

[Antonio65]

The group I'm talking about is

feline-hyperthyroid groups.io Group

 

[FeebysOwner]

In the US from what I have read, 2.5 - 5 mg seems to be the standard operating procedure for vets.

It does seem so, and some vets go higher than that. But I joined the group mentioned above, and it seems that the recommended standard for the group as a whole is 1.25mg twice a day and testing 3 weeks later, and then another 4 weeks after that to get to an ideal dose for each cat. Starting out with a smaller dose allows a cat's body to more easily adapt to the meds and helps to prevent adverse reactions. Most vets seem to think the faster they lower the T-4 the better - but not when it presents problems that cause discontinuation of the meds to re-set a cat's system, hence having to start all over again.

There are cats who don't do well on methimazole regardless, so that is why I thought the transdermal version would be another avenue for you to try.

 

[neely]

The dosing may be somewhat less accurate, but the advantage is it lessens the chance of gastrointestinal side effects so you would have a better chance of dosing your cat consistently.

I completely agree! When our cat was diagnosed with Hyperthyroidism last year the vet prescribed Methimazole and explained both the pills and the transdermal gel form. I chose the transdermal gel, 1.25 mg twice a day. It was much easier for me to administer, he didn't exhibit any side effects and did reasonably well on it. The vet discussed the I-131 treatment since he did not have any organ involvement and was a good candidate for it. We needed time to save up for the treatment but we're so glad we took that step.

 

[GandalfTGray]

I have requested transdermal from my vet and have an order in with a compounding pharmacy. Should be here in a few days, will let you know how it goes.

In the meantime, I don't know if I should keep Ed at 1.25mg twice per day as I've been doing, or cut back until the gel arrives. On the one hand, I really want to keep him consistently dosed before his blood test. On the other, I really want him to eat more.

 

[FeebysOwner]

What did the vet say to do given his lack of interest in food?

I personally think you are going to have to reset to 'Square One' before blood tests are done anyway considering he has already had a break with methimazole due to his reaction.

 

[GandalfTGray]

My vet didn't really say anything about reducing the dose or stopping; he just agreed to let me try the transdermal.

We re-set to 2.5mg on Aug 14, he has blood work scheduled for Sept 7.

 

[catmando2]

I'd love to hear more from people who use the transdermal, and its effectiveness and side effcts. My vet is reluctant to prescribe it because he thinks the dosing isn't as accurate.

Hi,
I have the opposite situation as you. My vet prescribed the transdermal gel to rmy cat with the intention of having that easier to give.

Others may have different experiences but for me the approach of rubbing some on the tip of the cat's ear is easier in theory than when applied. The gel I have gets dispensed in a syringe. I put the amount of dosage on a rubber glove or rubber tip on a finger and try to put that on the cat's ear.

So far after about 6 attempts. I managed to get that correctly applied with the proper amount 1 time. Other times, 1st try , the gel leaked down my finger. Now when my cat sees me near with a finger near his ear, he runs off.

I messaged my vet's office asking if I can try the pills instead and try hiding them in something like pet pockets.

 

[SundaesPerson]

Hi,
I have the opposite situation as you. My vet prescribed the transdermal gel to rmy cat with the intention of having that easier to give.

Others may have different experiences but for me the approach of rubbing some on the tip of the cat's ear is easier in theory than when applied. The gel I have gets dispensed in a syringe. I put the amount of dosage on a rubber glove or rubber tip on a finger and try to put that on the cat's ear.

So far after about 6 attempts. I managed to get that correctly applied with the proper amount 1 time. Other times, 1st try , the gel leaked down my finger. Now when my cat sees me near with a finger near his ear, he runs off.

I messaged my vet's office asking if I can try the pills instead and try hiding them in something like pet pockets.

The fingertip method didn't work for us either. We now just take the tube, click it to the correct dose and rub it directly from the tip into her ear. Also, if he eats wet food, maybe try giving him a little bit before dosing and then apply it while he eats.

My cat was much like yours when we started the transdermal. She would squirm and run, but we gave her some wet food and then applied it while she ate and it was so much easier for all of us

 

[catmando2]

The fingertip method didn't work for us either. We now just take the tube, click it to the correct dose and rub it directly from the tip into her ear. Also, if he eats wet food, maybe try giving him a little bit before dosing and then apply it while he eats.

My cat was much like yours when we started the transdermal. She would squirm and run, but we gave her some wet food and then applied it while she ate and it was so much easier for all of us

No such luck for me. I tried the wet food approach. But he then it's a game of he'll take a bite or two of the food, then squirm and run.

Of my attempts, the only time I applied correctly and the right amount was when he comes up for when I pet him and in a still moment I applied. But now, he still avoids once knowing my finger is near.

 

[Dos Gatos]

I have now had 2 hyperthyroid cats. We used the transdermal with Echo. She did great with the application (thought it was just an ear massage) but unfortunately I think there were dosing inconsistencies with it and we had a horrible time trying to control her T4. But it was on only option with her because she had a really sensitive stomach and the pills would have made her really sick.
With Loki, he was diagnosed in June and we used the pills in a pill pocket. That went went until he got a taste of the pill inside and started to be a little mess consistent with taking it. I also noticed that he seemed to just not feel great on methimazole. His appetite was up and down and he slept more. But the transdermal was not an option for him. The few times we tried Mirataz for him, you would think we were trying to murder him. I can rub his ears when petting him and he loves it, but the second I put the gel on my finger and touched his ear, he would freak out. We actually just got him I-131 on Monday because so he will hopefully be cured of hyperthyroidism soon.