What's the difference between 15 mg and 16.2 mg phenobarbital?

shandycat

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My cat has been on 15 mg pheno twice a day for years with great success. Today when I went in to pick up his new Rx, I noticed it was now 16.2. The tech could only tell me they were the same dosages, but...if they're the same, then why do manufacturers make both 15 and 16.2 mg? It doesn't sound like a big difference to me, but I don't know enough about it. I don't want to overdose him! Any help/advice would be much appreciated. Thanks!
 

di and bob

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Definitely call your vet and ask them, 1.2 mg. COULD be a huge difference in some meds, that much in insulin could kill someone. Only your vet would know if it is acceptable,  or call another pharmacist and ask them. Good luck and please let us know!
 
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shandycat

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I'm still waiting to hear back from my vet, but from the research I've done online it seems that they're interchangeable dosages. Seems weird to me because, as you say, even a small difference in dosages can cause big problems with some medications. What I did find out was that 15 mg can be hard for some pharmacies to source--all the ones I called yesterday said they'd have to order it. But when I asked about the 16.2, most had that readily in stock.  I'll post an update once I hear from my vet, hopefully today!
 

di and bob

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It could be that maybe your vet was unaware that the 16.2 dose is the 'common' one. Anything different, like your 15mg. dose would mean they would have to order it in or somehow make the 16.2 dose into 15mg. All of that requires extra work, so it most likely costs more too. Just like the uncommon 3 foot flourescent  light bulb is twice as much as the common 4 footer. I would just feel better having it explained by the vet! Good luck!
 
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