Transdermal Methimazole

Re: Transdermal Methimazole

Martin Atkinson — Fri, 19 Sep 2014 17:19:41 GMT

[quote user="Aisling McGrath"]This is probably a foolish question - but what are the precise health and safety risks to the owners if they are crushing Felimazole off license? Signs of hyperthyroidism? Heart problems? and toxicity to potential foetus in women of child bearing age?[/quote]No question is ever foolish only the answers!

Assuming the pet owner is stupid enough to crush the tablets with their fingers and lick them or sniff the powdered tablet both of which one would hope would be unlikely then the dose would still probably be too low to cause either of the former two but AFAIA the risk is that it is teratogenic in the first trimester so the latter is the concern and this is probably not dose dependent.

Re: Transdermal Methimazole

Aisling McGrath — Fri, 19 Sep 2014 16:33:42 GMT

This is probably a foolish question - but what are the precise health and safety risks to the owners if they are crushing Felimazole off license? Signs of hyperthyroidism? Heart problems? and toxicity to potential foetus in women of child bearing age?

Thanks!

Re: Transdermal Methimazole

Martin Atkinson — Fri, 19 Sep 2014 16:25:56 GMT

[quote user="Thomas Johnson"]The question I would ask of that trial is whether it was possible for the blue dye to be absorbed through the skin?[/quote]This is the question I asked of it myself but the point is that the cat obviously groomed its ears to get covered in the dye, the issue is whether the methimazole was absorbed before this or not? The bottom line seems to be that it seemed to be working so whether it went into the cat transdermally or orally doesn't really matter. I at least presume that the only reason it is advised to put it on the inside of the cat's ears is because that is somewhere they can't lick and is fur-free but clearly they can still groom the ears with their paws and lick the gel off.

Re: Transdermal Methimazole

Robin Grimmer — Fri, 19 Sep 2014 15:38:39 GMT

I have used it a few times but haven't had great results so far. I've just started a cat on it because the owners cannot give tablets. When the cat first came in and had a blood sample it got very stressed and became dyspnoeic so now the owners don't want to have any more blood tests, so it should be interesting!

I agree with Martin, I prefer Felimazole as there are a lot more dosage options and it can be crushed (off licence) so long as you warn of risks especially if the owners are female and of child-bearing age. I think I131 is a great treatment, the Feline Hyperthryoid centre in Wetherby has got its isolation time down to 1 week now.

Incidentally, how are people getting on with y/d?

Re: Transdermal Methimazole

Thomas Johnson — Fri, 19 Sep 2014 15:36:27 GMT

[quote user="Martin Atkinson"]

However (don't ask me for the reference) someone apparently put some dye with the gel and the dye ended up all over the cat's coat. The implication of this is that the cat was grooming itself and absorption consequently was likely as much oral as transdermal. If this is the case then there seems to be no reason why you shouldn't put it anywhere on the cat's skin and it will do the rest for you. Obviously monitor T4 and adjust dose accordingly. Its not cheap though.

[/quote]

The question I would ask of that trial is whether it was possible for the blue dye to be absorbed through the skin? If not then it's inevitable that it will eventually end up all over the cat. Whereas if the methimazole is well absorbed through the skin most of it may end up absorbed and in circulation before the cat has a chance to spread it over the rest of its coat.

Re: Transdermal Methimazole

Martin Atkinson — Fri, 19 Sep 2014 14:23:08 GMT

One of my clients was using it and she found it impossible to find enough surface area on the pinna to give the required dose and the cat was eventually referred for radio-iodine therapy.

Another possibility is to crush Felimazole tablets in the food, clearly warn the client it is at their own risk but as these are elderly it shouldn't be as much of an issue, the implication is health and safety rather than efficacy due to reduced pharmacoavailability as is the case with crushing carbimazole. Just don't say I told you!

Re: Transdermal Methimazole

Hannah May — Fri, 19 Sep 2014 10:34:27 GMT

woops looks like we were writing at the same time!

Re: Transdermal Methimazole

Hannah May — Fri, 19 Sep 2014 10:33:34 GMT

Hi!

There are a couple of discussions on the forum about this which I found useful when I was looking into it. They are: http://www.vetsurgeon.org/forums/p/12343/68846.aspx#68846 and http://www.vetsurgeon.org/forums/p/16418/97954.aspx#97954

Available from Summit Pharmaceuticals: http://www.svprx.co.uk/

I found them very helpful on the phone. I think they sent a list of safety/ handling precautions with the syringes, it comes in a pack of three 1 ml syringes (I think) which was around a months worth at starting dose (I think... haven't got the notes in front of me).

Hope that helps!

Re: Transdermal Methimazole

Busybee — Fri, 19 Sep 2014 10:30:00 GMT

Oh and just make sure the owner protects themselves from the drug during application!

Re: Transdermal Methimazole

Busybee — Fri, 19 Sep 2014 10:28:56 GMT

Summit Veterinary Pharmaceuticals. Comes in 3x1ml syringes to give a dose of 0.1ml/day onto the inside of the ear pinna so a box does ~1mo. I have one cat on it at present and it's working really well so far (pre-treatment T4 >129, after 3mo of treatment, T4 44).

Be aware though, they have no vets and not much information if you have any questions regarding the product, especially if you want to change the dose!