Azithromycin dosege (human variety) for rats, help needed

[Little_Lovelies]

Hi guys,

I've been meaning to get back here for months and have never quite got that far sorry! I hope you're all well

Our vet is fantastically knowledgeable about rats and has prescribed Azithromycin for our 650g male ratty who has been on and off antibiotics for respy things ever since we adopted him. Our vet was unable to get a hold of the normal one from their supplier and so very kindly managed to get us a human one instead. (No idea if there's some kind of a difference in the strength etc. for that reason?)

The label reads ~
200mg/5ml Powder for Oral Suspension
Powder to prepare 15ml (600mg) suspension.

Like I said he's absolutely brilliant with ratties but the doesage seems so high compared to everything that I've read online, and the vets is closed for today so I wanted to run it past you guys in case there's been a mix-up.
I've be asked to add 8ml of water to the powder, the bottle and leaflet also say this so that's all good. But I've been told to give my little fella 0.8ml twice a day for a minimum of 10 days. 0.8ml seems massive compared to any other antibiotics he's had before, and I keep reading online that they should have 8mg of this medicine so I'm wondering if there could have been some kind of confusion with ml Vs. mg? Or is there a difference between the human one & the standard one and that's why the dose is so high compared to others that I've read about? I know you give different doses for different issues but after a few hours looking I still haven't read about one this high.

Have any of you guys ever given 0.8ml or more of Azithromycin to any of your guys and gals?

Thank you so much! L.L.

[[cub]]

The BSAVA dosage of azithromycin for rats is 50mg/kg twice daily. 0.8mL of a 200mg/5mL solution contains 0.8*(200/5)=32mg, and 32mg/0.65kg=49mg/kg, which is actually a shade lower than the formulary dosage for a 650g rat, so yes, the dosage is not too high.

You can sometimes mix these powders for suspension with less water than indicated to produce a more concentrated suspension, just so you don't have to get as large a volume into the rat for the same dosage, but whether or not you can do that and to what degree you can do that depends a lot on the properties of the powder. Your vet can ask the manufacturer about the possibilities, if the volume of the dose is a concern.

I really don't know what these online sources you cite think that an 8mg dosage is meant to do in a rat, other than encourage antibiotic resistance.

[Little_Lovelies]

Hi Cub,

Thanks SO much for your reply! I was looking on http://ratguide.com/meds/antimicrobial_ ... omycin.php
and clearly getting the maths all wrong! I get so confused with the mg Vs. ml thing that I loose the plot a little! I can see now that it says 8mg per pound. I still don't really get the '15 mg/kg to 30 mg/kg, PO, q24hrs' bit though, is that just wrong do you think as I think what you're saying is that in giving him 0.8ml twice a day I'm giving him 32mg twice a day? And I think the above means 15-30 once a day? Again I might well just be being dim here though!!

He absolutely loves it thankfully, it smelt like a lovely milkshake to me so I had everything crossed and he actually drank it?! It's the first thing we haven't had to hide in food for him so let's hope he continues to like it

Thanks again SO much for your help and especially for explaining the calculations, that's really kind of you.

[[cub]]

I was looking on http://ratguide.com/meds/antimicrobial_ ... omycin.php
and clearly getting the maths all wrong! I get so confused with the mg Vs. ml thing that I loose the plot a little! I can see now that it says 8mg per pound. I still don't really get the '15 mg/kg to 30 mg/kg, PO, q24hrs' bit though, is that just wrong do you think as I think what you're saying is that in giving him 0.8ml twice a day I'm giving him 32mg twice a day? And I think the above means 15-30 once a day? Again I might well just be being dim here though!!

Rat Guide's dosages come from a variety of sources of ... varying quality. Their 4-8mg/lb twice daily dosage comes from the Rat and Mouse Club of America's medication chart, the quality of which I can't speak to but I wouldn't necessarily want to trust, especially not over an actual professional formulary. That chart is was also last revised in 2000 so it's really quite out of date by now. Rat Guide's 15-30mg/kg once daily dosage comes from Carpenter's 4th edition, which whilst a proper formulary is now out of date. It's also a general rodent dosage, vaguely applicable to everything from guinea pigs to hamsters. Carpenter's 5th edition now quotes the BSAVA's rat/mouse-specific dosage which as you can see is rather higher and also twice rather than once daily.

q24h does mean once a day yes; qNh in general means every N hours. BID means twice a day, TID three times a day. PO just means dosing orally.

You're lucky he's keen on the stuff; not everyone finds the banana flavour convincing. If he does get tetchy (which he might do if he starts getting side effects) you may have to syringe it, which is not fun with 0.8mL but doable. But hopefully he'll just keep thinking it's a delicious treat.

[Little_Lovelies]

Wow I can't believe how much has changed since that was written! What a shame the page isn't kept up-to-date. He's been pretty good about taking it most days, seems to depend what mood he's in! lol.

Thanks so much for explaining all of that, it's really interesting to know more about this stuff