yikes, kristin, i'm so sorry she's having such an extreme reaction. I don't have experience with feline hypertension, but have taken BP meds myself. I spent a year on one that just knocked me out (a beta blocker - Calley's is a calcium channel blocker). The doc did want me to stay on it, but I never got used to it and eventually he switched me to another one.
I found this link to a pharmacy (which I don't know anything about) but thought I'd at least pass it on in case there is something useful for you:
Treating High Blood Pressure with Amylodipine (copying and pasting below):
I highlighted and bolded in red below the side effects that require a vet - if I were you, I would get an opinion from another vet. Or call the vet you're seeing and say you think this looks more like shock or a coma than lethargy, if that is what you think. I think lethargy means tired and not wanting to do anything but it doesn't mean unresponsive. Your descriptions sound very serious and scary.
Sending you and Calley all the best thoughts. Please keep us up to date on what's going on.
Amlodipine besylate is classified as a calcium channel blocker medication, and it is effectively used in veterinary medicine to treat hypertension, or high blood pressure, in cats and dogs. Compounded in an oral suspension, it is most commonly administered to cats that are also suffering from kidney disease.
How Does Amlodipine Work?
Amlodipine slows the rate at which calcium moves into the heart and blood vessel walls. This enables the blood vessels to relax, which ultimately results in better blood flow. The effects of Amlodipine also make it much easier for the heart to pump blood throughout the body, which lowers the pet’s blood pressure.
Administration of Amlodipine
When giving your cat or dog Amlodipine, it is important to follow the directions of your veterinarian. It is also very important that you not miss a dose as this can cause a sudden rise in the pet’s blood pressure. A sudden spike such as this can cause a pet to suffer seizures, kidney damage or blindness.
If you missed a dose, give your pet a dose immediately, or, if it is close in time to their next dose, use that dose to get back on schedule. Never give your pet 2 doses at the same time. In the case of an accidental overdose, please call your veterinarian immediately. Signs of overdose include a very slow heart rate, staggering, dizziness or collapse.
Possible Side Effects of Amlodipine
Side effects of Amlodipine are quite rare in
veterinary medicine, but in some cases, the cat or dog may exhibit lethargy, loss of appetite, weight loss, swelling of the gums or a slight increase in their heart rate. It they get a laceration, it may also take longer for it to clot.
If your pet exhibits an allergic reaction, call your veterinarian immediately. Signs of an allergic reaction to Amlodipine can include sudden onset diarrhea, swelling of the face, itching, vomiting, hives, pale gums, cold limbs or the symptoms of shock or coma.
Amlodipine Precautions
Amlodipine should not be administered to cats or dogs that have liver disease. Female pets that are pregnant or lactating should not be administered the medication. Male and female pets that are breeding should also not receive Amlodipine.
If your pet is already taking heart medication, diuretics, vitamin supplements, aspirin or other medications that can affect their blood pressure, please consult with your veterinarian before administering Amlodipine as interactions may occur.
In general, the
compounding pharmacy will recommend that Amlodipine be administered to patients with their food. Treatment should be completed as directed by the prescribing veterinarian in order to successfully treat the pet’s high blood pressure.