Stability of acetazolamide in suspension compounded from tablets

Area of Science:

• Pharmaceutical Sciences
• Drug Stability
• Formulation Development

Background:

• Acetazolamide is a carbonic anhydrase inhibitor used to treat various conditions.
• Extemporaneous compounding of oral suspensions is crucial for pediatric and geriatric patients or those with swallowing difficulties.
• Assessing the stability of compounded medications ensures therapeutic efficacy and patient safety.

Purpose of the Study:

• To evaluate the stability of an extemporaneously compounded acetazolamide oral suspension (25 mg/mL) prepared from 250-mg tablets.
• To determine the optimal storage conditions and predict the shelf life of the compounded suspension.

Main Methods:

• Acetazolamide suspension was prepared using comminuted tablets, sorbitol solution, and a vehicle containing magnesium aluminum silicate and carboxymethylcellulose sodium.
• The suspension was stored in amber glass bottles at various temperatures (5°C, 22°C, 30°C, 40°C, 50°C).
• Stability was assessed using stability-indicating high-performance liquid chromatography (HPLC) over 79 days.

Main Results:

• Acetazolamide concentration remained stable for 79 days at 5°C, 22°C, and 30°C.
• At 40°C and 50°C, concentrations fell below 90% of the initial value after 79 and 32 days, respectively.
• An Arrhenius plot predicted a room temperature shelf life of 371 days.

Conclusions:

• The extemporaneous acetazolamide oral suspension (25 mg/mL) is stable for at least 79 days when stored at temperatures between 5°C and 30°C.
• The formulation should be maintained at pH 4-5 and protected from light by storing in amber glass bottles.
• This study supports the use of this compounded suspension for short-term storage at controlled room temperatures.