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Ask Dr. Michael Salkin Your Own Question
Dr. Michael Salkin
Dr. Michael Salkin, Veterinarian
Category: Cat Veterinary
Satisfied Customers: 29793
Experience:  University of California at Davis graduate veterinarian with 45 years of experience.
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My vet is giving my cat injections of Crystiben, penicillin

Customer Question

My vet is giving my cat injections of Crystiben, penicillin combo antibiotic. I am reading the ingredients are the same as PEN BP 48, which must not be given to cats.
Can you tell me if Crystiben is supposed to be given to cats??
I do not understand
Submitted: 1 year ago.
Category: Cat Veterinary
Expert:  Dr. Michael Salkin replied 1 year ago.
Julie, I'm sorry that your question wasn't answered in a timely manner. Crystiben only contains procaine penicillin G. Please see here:
Expert:  Dr. Michael Salkin replied 1 year ago.
It's dosed as 20,000-40,000 units/kg IV or IM every 4-8 hours to cats. Please respond with further questions or concerns if you wish.
Customer: replied 1 year ago.
The Crystiben he gave my cat is Cristiben Injection 300,000u/ml. Subq, with another injection in 3-5 days. He told me it has two kinds of Penicillin in it, one short acting and one long acting. Which is what PEN BP 48 has in it.
Customer: replied 1 year ago.
Here is some info I found
Customer: replied 1 year ago.
Am I ever confused.
At the very least, this should not be given to my cat subq, correct?
Expert:  Dr. Michael Salkin replied 1 year ago.
I believe that he misspoke. There certainly are combination penicillins containing both procaine and benzathine penicillin but as you can see Cristiben only contains procaine. In any event, benzathine penicillin isn't toxic to cats; it just isn't appropriate because it doesn't reach effective serum levels. I give the procaine subcutaneously without harm. According to Plumb's Veterinary Drug Handbook, 8th Ed., Plumb, 2015, IM or SQ is acceptable. Please continue our conversation if you wish.
Customer: replied 1 year ago.
This link lists Crystiben as a combo penicillin.
Customer: replied 1 year ago.
To you know why the benzathine doesn't reach appropriate serum levels in cats, but is apparently okay in other animals?
I'm not meaning to argue, I'm just trying to figure out what to do for my cat!!
Expert:  Dr. Michael Salkin replied 1 year ago.
I can only imagine that Crystiben for goats isn't the same Crystiben for dogs and cats. Confusing to be sure. The pharmacokinetics of benzathine in cats reveal that it never reaches effective serum levels in that species. The pharmacokinetics in other species varies from the cat and makes benzathine appropriate in those species. The very long-acting benzathine is convenient when treating large animals I might only have one chance to capture and treat. If a vet only has the combo product it can be dosed to cats as per the procaine in it and accept that the benzathine isn't going to be helpful.
Customer: replied 1 year ago.
So in other words, there is no point in me getting my cat a second injection three days after the first injection.
Thank you for the information.
Expert:  Dr. Michael Salkin replied 1 year ago.
Correct. In fact, penicillin is rarely a first choice antibiotic in cats. What was it supposed to address, please?
Customer: replied 1 year ago.
UTI. Oral medications trigger her pancreatitis and she vomits and is in pain, she is also diabetic and the vomiting makes the diabetes more difficult. I don't know what to do! Find a new vet maybe.
Expert:  Dr. Michael Salkin replied 1 year ago.
Penicillin would be a poor choice for a UTI. The long acting injectable cefovecin (Convenia) is broad spectrum and makes more sense for such a patient.