The supply of Zarontin (ethosuximide) capsules has been disrupted

From August 2022 until early 2023, supplies of Zarontin capsules will be disrupted and will be replaced by Ethosuximide Essential Generics capsules. Zarontin capsules contain the medicine ethosuximide which is used to control seizures, mainly in children. To maintain control of your or your child's epilepsy and prevent seizures, it's really important to continue taking ethosuximide.  

What is happening to Zarontin capsules and why?

From August 2022, supplies of Zarontin capsules will begin to be disrupted. The supplier experienced an issue with the shipment of Zarontin capsules, which was meant to arrive in July 2022. To ensure people can keep taking their medicine, the suppliers have secured an alternative brand of ethosuximide capsules called Ethosuximide Essential Generics.

This disruption is temporary – supplies of Zarontin capsules are expected in early 2023, when it will be available in New Zealand again.

Note: There are no supply issues with the Zarontin oral liquid.

Ethosuximide Essential Generics is the alternative brand

Ethosuximide Essential Generics is the replacement brand for ethosuximide capsules. Ethosuximide Essential Generics is made by the same manufacturer as Zarontin, but at a different manufacturing site.

While the active ingredients are the same, there are additional preservatives in the new medicine that you should talk to your GP, nurse or pharmacist about.

The Ethosuximide Essential Generics packaging and capsules look different. Each capsule has the same amount of ethosuximide as Zarontin capsules and works in your body in the same way.

Image credit: Pharmac

Ethosuximide Essential Generics is not Medsafe approved 

Ethosuximide Essential Generics is approved for use in the United Kingdom, but it has not been through the Medsafe approval process in New Zealand. Unapproved medicines may have acceptable quality, efficacy and safety, but approval to supply these medicines has not been sought in New Zealand. Being unapproved does not mean the medicine is ‘unsafe’. Your healthcare provider will discuss the benefits and risks of the medicine with you. Read more about unapproved medicines

What happens next?

Your doctor, nurse or pharmacist will talk to you about this temporary medicine change and get your consent. You will have a chance to ask questions and share any concerns about the brand change then.  


  1. Ethosuximide (Zarontin) 250 mg capsules: Supply issue Pharmac, NZ
  2. Ethosuximide Essential Generics 250 mg Capsules Datasheet
  3. Upfront: unapproved medicines and unapproved uses of medicines – keeping prescribers and patients safe BPAC, NZ, 2013