Treatment of Drug Resistant Seizures with Zonisamide

By James Wiernas, Pharm D.

While most dogs respond very well to Phenobarbital and/or Potassium bromide, there are some that will continue to have a high seizure frequency despite having adequate serum levels of these medications and are called “refractory”. For these dogs newer anticonvulsants may be of help. One example of these newer anticonvulsants used in cases of refractory epilepsy is Zonisamide.

What is Zonisamide

Zonisamide is an antiseizure medication that can be quite useful in adjunctive therapy. In 2004 study reviewing 12 poorly controlled idiopathic epileptic dogs, 58% responded favorably with a mean reduction in seizures by 81.3% (Dewey, 2004). Another study from 2007, showed 9 out of 11 dogs received a median reduction of 70% in seizure frequency (von Klopmann, 2007).

Compounding Zonisamide

Zonisamide is currently on the NIOSH list, which evaluates a drug’s potential to affect personnel compounding with the respective medication. Zonisamide is classified as a Group 3, which focuses on reproductive risk potential. The reason this is particularly important is that Pharmacy Solutions has completed an extensive renovation to the pharmacy. This extension includes a brand-new laboratory devoted solely to compounding hazardous products in compliance with <USP 800>.

We are committed to providing excellent services and quality in the safest manner possible.

Dosing

Refractory Epilepsy in Dogs: 10mg/kg PO Q12hrs

References

1. Dewey CW, Guiliano R, Boothe DM, et al. (2004). Zonisamide therapy for refractory idiopathic epilepsy in dogs. J Am Anim Hosp Assoc. 40(4):285‐291. doi:10.5326/0400285.
2. Von Klopmann T, Rambeck B, Tipold A. (2007). Prospective study of zonisamide therapy for refractory idiopathic epilepsy in dogs. J Small Anim Pract. 48(3):134‐138. doi:10.1111/j.1748-5827.2006.00290.x.