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Zarontin (ethosuximide) is an anticonvulsant succinimide, chemically designated as alpha-ethyl-alpha-methyl-succinimide, with the following structural formula:
Each Zarontin capsule contains 250 mg ethosuximide, USP. Also contains: polyethylene glycol 400, NF. The capsule contains D&C yellow No. 10; FD&C red No. 3; gelatin, NF; glycerin, USP; and sorbitol.
To report an adverse event related to Pfizer-BioNTech COVID-19 Vaccine (also known as COMIRNATY®, COVID-19 mRNA, Vaccine BNT162b2 or BNT162) or Pfizer COVID-19 Treatment (also known as PAXLOVID™ (nirmatrelvir tablets; ritonavir tablets)), and you are not part of a clinical trial* for this product, click the link below to submit your information:
*If you are involved in a clinical trial for either product, adverse events should be reported to your coordinating study site.
If you cannot use the above website or would like to report an adverse event related to a different Pfizer product, please call Pfizer Safety at