In the process of confirming this with my vet, but for those of you treating crf (chronic
renal failure) kitties, I need to relate this experience as a note of caution on a possible
drug interaction.

Both my two cats have been on blood pressure medication, Norvasc (generic name Amlodipine), one-quarter
of a 2.5 mg tablet, for over a year for high blood pressure as a result of renal failure.

One cat's dosage was about two weeks ago increased to one-half of a 2.5 mg tablet of Amlodipine, and the
cat seemed fine with this dosage increase and was behaving normally.

Periactin (Cyproheptadine hydrochloride aka Cypro) is used as an appetite stimulant for crf kitties whose
appetites go down. The usual vet recommended dosage is often one-half daily of a 4mg Periactin (Cypro) tablet
to start and see if this brings about increased eating without some well known but usually harmless side effects.

About day three of this combination of blood pressure med and appetite stimulant, my cat was just flat. Eating
and no vomitting or diarrhea, but just laying there really lethargic and with a definite personality change to just
too quiet, no personality, and a little bit disoriented.

Called vet, who said to check for femoral pulse. I could not get one. That apparently means the blood pressure
is probably too low.

Therefore, the conclusion seems to be that if your crf cat is on blood pressure medicine and is using Periactin (Cypro)
to pick up appetite, be sure the vet thinks about the combination effects of the two medications. Stopped Cypro, lowered dosage
 of blood pressure med, and cat behavior returned to normal by the next day. This is a perhaps not often considered complication
you can run into and one to keep in mind should your cats be taking both medications. Much human side effect information
on the internet mentions possible lower blood pressure from Periactin/Cypro, but most of the feline information does not say much
about it. Scary, though, and just something to keep in mind based on this pet parent's experience.

Did not have a problem with Periactin/Cypro when both my cats were on the one-quarter 2.5 mg tablet blood pressure medicine dose. But the one that has gone up to one-half of a 2.5 mg tablet amount sure did. Just be careful and ask your vet. Hopefully it won't
happen, but the first vet I talked to was not even aware that Periactin/Cypro could lower blood pressure.

Just got off the phone with my regular vet who confirms that Periactin/Cypro can cause
lowered blood pressure, and the combo of Norvasc/Amlodipine and Periactin/Cypro could
result in too low of a blood pressure. Does not do this always, but is possible, especially
in kitties treated for chronic renal failure with high blood pressure. So it's another thing
to put in the information you collect and keep in mind on chronic renal failure with high
blood pressure pet parent file.

Ask your vet how to feel for a femoral pulse before you need it, too. A little tricky ...

I'm glad for the bounce back, too. My little girls are on life eight and something, and
I wouldn't give up one lovable minute intentionally. Their behavior seems to be the
best guide on what questions to ask.

Thanks so much for sharing this, 3cat. KD is on a blood pressure med (benazepril aka Fortekor) for her CRF and also gets Periactin for appetite. She's been on this combo for a year with no apparent ill effects, but I'll be sure to ask the vet at our next visit what I should be looking out for. But her reaction to Periactin is a little backwards - it causes sedation in most cats but agitation in her - so hopefully she's dodged this bullet.

3Cat, Im sorry to hear about this but am glad you and the vet figured it out.   This is another thing that makes me very angry about the toxic pet food.  PFC's if you are reading this, see the results of your 2007 pet food recalls?   

I think Norvasc is a different class of medication than Fortekor. I did a quick search on the generic names, and it looks like they work in totally different ways. So it may only be an issue for certain blood pressure medications.

KD gets a lower dose of Periactin. She started on half a 4 mg tablet as needed, but she had too many side effects so I cut it down to a quarter tablet.