Oral pharmaceutical composition comprising zonisamide and process of preparation thereof

A liquid oral pharmaceutical suspension, comprising:

• zonisamide in an amount of about 20 mg/mL;
• a suspending agent comprising about 2 mg/mL to about 3.5 mg/mL xanthan gum and about 20 mg/mL of a combination of microcrystalline cellulose and sodium carboxymethylcellulose;
• one or more buffering agents;
• and
• one or more pharmaceutically acceptable excipients, wherein the one or more pharmaceutically acceptable excipients comprise a preservative;
• wherein the liquid oral pharmaceutical suspension has a pH of 3.5 to 5.0, wherein the composition is stable for at least 6 months when stored at 40° C. and 25% relative humidity.