Fortum (ceftazidime) dosage rates

[DaveB]

A friend is experiencing problems with his koi and a swab has been sent off to Paula Reynolds and after testing for the best antibiotic, she has recommended Fortum.10 grams per 1 kg of fish.Every other day for 3 injections. Because we could not work out how to mix the powder with the water to be able to use 1ml injections if you get my meaning, A very reputable local dealer who has used Fortum before has instructed to mix 500mg of Fortum to 5ml of water and inject 0.5ml of the mixture per kg of koi once per week also for 3 injections. Unless my maths is incorrect this is a huge difference in the amounts. The latter being 50mg of Fortum per Kg of koi(5 times the prescibed amount) although the interval between each injection is longer.Your thoughts would be much appreciated especially if I am looking at this the wrong way. Best Regards Dave

[Manky Sanke]

Dave,

If you meant that Paula recommended 10 mg per kilo compared with the dealer's recommendation then the arithmetic would be correct - the dealer is saying 5 times more but less frequently.

But 10 gm per kilo is 200 times what the dealer is saying, and it's more frequent.

I have to talk to her on another matter tommorow, I'll ask her to clarify.

[DaveB]

Sid Your input is much appreciated & I look forward to any further clarification after you have talked to Paula. Best Regards Dave

[Manky Sanke]

Dave,

I phoned Paula and, as I thought, it was 10 milligrams that she recommended not 10 grams (that's the dose for a small Minky Whale).

She also said that her dose was the correct one to administer and that the report said that in case of queries you should contact her so don't think you would be imposing, she's happy to help.

[DaveB]

Cheers Sid.
Much \appreciated. Just for the record it is now my intention to mix 25 ml of surgical water with 500mg bottle of Fortum then give 0.5 ml injection with for every 1 kg of fish. Suppose the koi wieghs 4 kg then the koi in question would require 2 x 1ml injection,giving a total of 40mg of fortum per treatment.I know this is not exactly right but wonder if it would suffice. I will try and give Paula a call to see what she has to say. Thanks once again Best Regards Dave

[Manky Sanke]

Dave,

Unless I've misunderstood, I don't see the flaw in your arithmetic or why you think your plan might not be exactly right.

If you start with a 25 ml solution and inject 0.5 ml of it then you will have divided the solute (the stuff you mixed in) by 50.

If the solute was 500 mg then one fiftieth of that is 10 mg so you will have injected 10 mg (per kilo) which is what Paula said.

A 4 kg fish will require four times that dose which is 4 x 0.5 ml which equals 2 ml and will deliver 40 mg (4 x 10 mg).

To double check, another way to look at that is to say that if you start with a 25 ml solution and take 2 ml of it then you have divided the solute by 12.5

500 mg divided by 12.5 equals 40 mg which is the correct dose for a 4 kg fish at 10 mg per kilo.

The two different ways come out the same.

[DaveB]

Sid
Glad to hear that you agree with me and for once my arithmetic is correct. Best Regards Dave

[Duncan]

Dave, For your information i routinley use fortum at 25 mg per kilo EOD for three doses and have had no problems at all. i mention this should you wish to upgrade the dose, you know it to be safe to do so as long as you do not go mental with it

dunc

[DaveB]

Dave, For your information i routinley use fortum at 25 mg per kilo EOD for three doses and have had no problems at all. i mention this should you wish to upgrade the dose, you know it to be safe to do so as long as you do not go mental with it

dunc

Thanks Duncan, Your timely input is much appreciated and duely noted. I plan to try it out next week. paula did mention to my friend something about higher doeses can fry the kidneys and therefore wonder what is the best way forward regarding the type of injection. As there are 3 injections in all. I was thinking of 1 in each peck and then the final one being underneath which I believe to be an IP injection. At your higher dosage I would be interested to know in which injection sights you would use to avoid any kidney damage. Your thoughts on this would be much appreciated.
Also could you confirm for a 4 kg koi , I would need to mix 500mg of Fortum with 5ml of water and inject 1ml giving a total of 100mg of Fortum. Best Regards Dave

[Duncan]

Dave,

Let me first say I personally know of no other dose for fortum other than the 25mg per kilo which I mentioned, that’s not to say Paula is in error with her dose, It’s just there is very little data for fortum as used in piscine medicine. Further with antibiotics, it does not always follow that more will do the job better, the correct dose is exactly that, the correct dose and to add more is, A) not only a waste as it will be filtered out by the kidney, B) as Paula says more can do permanent damage. And I trust Paula and her dose rate, I only mention the higher dose that I use to show if you cannot get the dose accuracy needed you have got a margin of error you can employ.

Next, injection sites, I always inject IP which as you say is underneath the koi. This has the advantage of getting a free circuit around the koi by-passing the kidney on the first circuit, in short you get one circuit before the kidney starts filtering.

If you don’t have the confidence to do IP under the koi you can actually do this by the pec muscle, instead of injecting into the muscle look for the crease line between the body of the muscle and the koi’s flank and inject into this crease line, this put’s the injection into the peritoneal cavity

And last, yes if you want to inject at 25mg per kilo add 500 mg to 5 ml of sterile water that will give you a 10% solution or 100 mg per ml, and inject your 4kg koi at 1ml per injection dose, but having heard what Paula has to say I would be inclined to go at 0.5ml which would be 12.5mg per kilo (50 mg per 4 kilo), and be more manageable and closer to Paul’s recommended dose

Also if you make the full 5 ml up split it in five separate syringes what you don’t use freeze, a flaw with fortum is it does not keep but will keep for a year or more if frozen

[DaveB]

Hi Duncan and thanks for clearing things up for me and offering even more information, especially about freezing after mixing.
Best Regards Dave