Doses - PRIMIDONE

Dogs:

a) 15 - 20 mg/kg per day divided bid-tid initially; some dogs require 50 mg/kg/day(Morgan 1988)
b) 11 - 22 mg/kg tid (Kay and Aucoin 1985)
c) Initially, 15 mg/kg divided bid; up to 80 mg/kg divided bid (Bunch 1986)
d) 55 mg/kg PO once daily (Kirk 1986)
e) 55 mg/kg PO daily; if seizures are frequent, divide daily dose. Reduce dosage gradually, never discontinue abruptly. (Package Insert; Mylepsin® - Fort Dodge)

Cats:

a) 11 - 22 mg/kg tid (Davis 1985b)
b) 20 mg/kg PO q12h (Neff-Davis 1985)
Monitoring Parameters -

1) Anticonvulsant efficacy

2) Adverse effects (CNS related, PU/PD, weight gain)

3) Serum phenobarbital levels if lack of efficacy or adverse reactions noted. Although thereis some disagreement, therapeutic serum levels in dogs are thought to mirror those inpeople at 15-40 micrograms/ml.

4) If used chronically, routine CBC's and liver enzymes at least every 6 months
Client Information - Compliance with therapy must be stressed to clients for successful epilepsytreatment. Encourage to give daily doses at same time each day. Veterinarian should be contacted ifanimal develops significant adverse reactions (including symptoms of anemia and/or liver disease)or if seizure control is unacceptable.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times - Veterinary-Approved Products:
Primidone 250 mg Tablets; Neurosyn® (Techamerica), generic; (Rx) Approved for use in dogs.

Human-Approved Products:

Primidone 50 mg, 250 mg Tablets; Mysoline® (Wyeth-Ayerst); (Rx); generic (Rx)Primidone Oral Suspension 50 mg/ml in 8 oz. bottles ; Mysoline® (Wyeth-Ayerst); (Rx)
Additional names and trade names include: Myidone® (Major), and Primaclone.