Potassium Bromid & Falbatrol

To Whom It May Concern, I would like to know if I would be able to purchase the above mentioned prescription drugs (potassium bromide & falbatrol). My Lhasa Apso has constant seizures. My vet is still trying to figure out what is causing these seizures. The prescription drugs my dog needs is starting to get very expensive. The Falbatrol I purchase through my Pharmacy each month. The cost each month is $52.00. My vet believes my dog may have Cushings disease (I have agreed with my vet not to put him on the drugs for the Cushings Disease. The medication would be to drastic for him). He does have the extended belly. Would the Cushings cause the constant seizures. Thank you. Louise Bistany