Dose of meloxicam in guinea pigs

RE: Dose of meloxicam in guinea pigs

Charlotte Marshall — Fri, 17 Aug 2018 22:26:47 GMT

[quote user="Marie Kubiak"]

[/quote]

I have been using similar doses for the same reason. Though often only sid. I shall probably carry on as it seems to be well tolerated and effective.

RE: Dose of meloxicam in guinea pigs

Rob Loxley — Thu, 16 Aug 2018 16:32:07 GMT

[quote user="Charlotte Marshall"]What dose are others using?[/quote]

From the Metacam EMEA submission http://www.ema.europa.eu/docs/en_GB/document_library/EPAR_-_Assessment_Report_-_Variation/veterinary/000033/WC500252297.pdf :

No dose determination/confirmation studies have been performed by the applicant. The proposed oral dose of meloxicam (0.2 mg /kg body weight induction dose followed by a once daily dose of 0.1 mg/kg body weight for two additional days) was supported by expert opinions and published data from uncontrolled studies and case reports using doses ranging between 0.1 and 0.5 mg/kg administered once or twice daily. Safety and efficacy with respect to pain relief of meloxicam was not objectively evaluated in the [these] studies provided.

The efficacy of meloxicam when administered at the selected dose was evaluated in a single laboratory study... ...involving 30 male guinea pigs undergoing surgical castration

Interestingly, this study didn't actually measure pain but used feeding behaviour as a surrogate marker (and only just reached statistical significance). So I'm not convinced the Metacam data answers such questions about dose rate and frequency. The metacam work also had tolerance data with dosing at 3x their labelled dose for 3x as long if you are using higher doses, but these are now more 'off-label'.

The CVMP acknowledged that the data supporting the efficacy in the proposed indication for guinea pigs are rather limited; however, there are no recognised models to investigate this indication in the target species, and guinea pigs are considered a "minor species". In the absence of any alternative authorised treatment options for this indication, and in view of the wide safety margin of meloxicam at the recommended dose, the Committee considered that for animal welfare reasons, the limited data package would be acceptable

Whether welfare is well served by the lack of dose determination/confirmation studies, possibly leading to people reducing the dose they are otherwise giving based on just looking at the headline new datasheet dose, without understanding the caveats and limitations of the data to support such dose rate?

RE: Dose of meloxicam in guinea pigs

Marie Kubiak — Thu, 16 Aug 2018 13:49:43 GMT

[quote user="Charlotte Marshall"]

I just looked up the new license for metacam for use in guinea pigs. I was surprised to see it is an initial dose of 0.2 mg/kg followed by ongoing at 0.1mg/kg. I have always used rabbit doses for them especially as quoted doses for smaller rodents are even higher. What dose are others using?

There does not seem to be a specific dose for guinea pigs in the bsava formulary.

(Also why did they get a license for guinea pigs and not rabbits?)

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I am surprised by this too.

If rabbits require 0.3-1 mg/kg and smaller sciuromorph and myomorph rodents require 1-2mg/kg generally (based on published pharmacokinetics) then I don't understand why a guinea pig would need a lower dose in the absence of any pharmakokinetic/pharmacodynamic studies. I tended to opt for 0.5-1 mg/kg bid as an best guess by extrapolating rabbit doses I used given the similar GIT physiology with a slight increase based on allometric scaling. This seemed to give reasonable analgesia compared to more cautious doses (0.2mg/kg sid/bid) used before rabbit studies came out. I monitored renal values in some on long-term meloxicam and never had any concerns about renal side-effects. Maybe they have just copied cat doses to be cautious?? Or they have some data from trials that is being withheld which would seem odd if it supports use of their product.

I also don't get why rabbits are not included on the licence when there is much more published data on rabbits (albeit small scale studies) and the potential market is more lucrative... Though saying that I'm not sure anyone uses a different NSAID for rabbit patients so they have cornered the exotics market already.

Marie

RE: Dose of meloxicam in guinea pigs

David Mills — Mon, 13 Aug 2018 22:22:23 GMT

We use the guidance from labs for anaesthesia in small furries. The US universities have lots of free material, and meloxicam in GPs is 0.2mg/kg sq then 0.1mg/kg po. Its possibly based on this?