Topiramate 20 mg/mL Oral Suspension

US Pharm. 2017;42(5):46-47.

Method of Preparation: Calculate the quantity of each ingredient for the amount to be prepared. Accurately weigh or measure each ingredient. If tablets are used, pulverize them to a fine powder. Mix the powder with about 10 mL of Ora-Plus to form a smooth, uniform paste. Geometrically, incorporate the remainder of the Ora-Plus and mix well. Add the Ora-Sweet to final volume and mix thoroughly. Package and label.

Use: Topiramate is used as an anticonvulsant and for preventing migraine headaches.

Packaging: Package in tight, light-resistant containers. Store at controlled room temperature or in a refrigerator.

Labeling: Keep out of the reach of children. Store at either room temperature or refrigerated temperature. Shake well. Discard after ____ [time period].

Stability: A beyond-use date of up to 90 days stored at either room temperature or refrigerated temperature may be used for this preparation.¹ It should be noted that the beyond-use date is the same for either storage temperature.

Quality Control: Quality-control assessment can include weight/volume, pH (3.9-4.9), specific gravity, active drug assay, color, rheologic properties/pourability, physical observation, and physical stability (discoloration, foreign materials, gas formation, mold growth).²

Discussion: Topiramate 20 mg/mL oral suspension is used for treating seizures in certain patients, and it may be used alone or with other medications. Topiramate is also used to prevent migraine headaches. In addition, topiramate may be used for other conditions, as determined by the physician. Topiramate works by acting on several chemicals in the brain that help reduce seizure activity and prevent migraine headaches from occurring.³ Topiramate 20 mg/mL Oral Suspension USP is an official, monographed compounded preparation.

Topiramate (Topamax, C₁₂H₂₁NO₈S, MW 339.36) occurs as a white to off-white powder with a bitter taste. It is most soluble in alkaline solutions containing sodium hydroxide or sodium phosphate and having a pH of 9 to 10. Topiramate is freely soluble in acetone, chloroform, dimethylsulfoxide, and ethanol. Its solubility in water is 9.8 mg/mL, its saturated solution has a pH of 6.3, and it contains not more than 0.5% water. The powder should be preserved in tight, light-resistant containers and stored at controlled room temperature.^1,3

Topiramate products are available from several manufacturers. Commercially manufactured topiramate products include sprinkle capsules (15 mg and 25 mg) and tablets containing 25 mg, 50 mg, 100 mg, or 200 mg of topiramate USP. Because of the bitter taste, tablets should not be broken. Topiramate tablets may be taken without regard to meals. No oral liquid dosage form is commercially manufactured, however.

Topiramate tablets contain the inactive ingredients lactose monohydrate; microcrystalline cellulose; pregelatinized starch (maize); sodium starch glycolate; magnesium stearate; and Opadry white (titanium dioxide, hypromellose 3cp, hypromellose 6cp, polyethylene glycol 400, polysorbate 80) for the 25-mg tablets, Opadry yellow (titanium dioxide, hypromellose 3cp, hypromellose 6cp, polyethylene glycol 400, polysorbate 80, iron oxide yellow) for the 50-mg tablets, Opadry yellow (hypromellose 3cp, hypromellose 6cp, titanium dioxide, polyethylene glycol 400, iron oxide yellow, polysorbate 80, iron oxide red) for the 100-mg tablets, and Opadry pink (titanium dioxide, hypromellose 6cp, polyethylene glycol 400, iron oxide red) for the 200-mg tablets.³

Ora-Plus is an oral suspending vehicle that accepts dilution of up to 50% or more with water, flavoring agents, or syrups and still retains its suspending properties. It has a pH of approximately 4.2 and an osmolality of about 230 mOsm/kg. Ora-Plus is a thixotropic vehicle with a viscosity of approximately 1,000 cps at 25°C. It contains purified water, microcrystalline cellulose, sodium carboxymethylcellulose, xanthan gum, carrageenan, sodium phosphate, and citric acid as buffering agents; simethicone as an antifoaming agent; and potassium sorbate and methylparaben as preservatives.⁴

Ora-Sweet syrup vehicle is a flavoring vehicle for oral extemporaneous preparations. It is flavored with a citrus-berry flavor blend and contains glycerin and sorbitol to prevent cap lock, a problem associated with many syrups. Ora-Sweet is buffered to a pH of about 4.2 and has an osmolality of about 3,240 mOsm/kg. It contains purified water, sucrose, glycerin, sorbitol (5%), flavoring, sodium phosphate, and citric acid as buffering agents and potassium sorbate and methylparaben as preservatives.⁵

REFERENCES

1. U.S. Pharmacopeia/National Formulary [current revision]. Rockville, MD: U.S. Pharmacopeial Convention, Inc; April 2017.
2. Allen LV Jr. Standard operating procedure for performing physical quality assessment of oral and topical liquids. IJPC. 1999;3:146-147.
3. Drugs.com. Topiramate. www.drugs.com/pro/topiramate.html. Accessed March 29, 2017.
4. Ora-Plus product information. Allegan, MI: Perrigo; 2014.
5. Ora-Sweet product information. Allegan, MI: Perrigo; 2014.

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