Stability of extemporaneously prepared clofazimine oral suspensions

Background

Clofazimine is recommended as a treatment for tuberculosis in infants. Extemporaneously prepared clofazimine oral suspensions are more appropriate dosage forms for infants than tablets, however no data exist to inform appropriate storage conditions.

Aim

To examine the physical and chemical stability of extemporaneously prepared clofazimine oral suspensions and determine appropriate storage conditions.

Method

An oral suspension of clofazimine 10 mg/mL was prepared by grinding six 100 mg clofazimine tablets to produce a fine powder. Ora-Blend SF (sugar free) was added to make a final volume of 60 mL. Six 10 mL aliquots were placed in amber plastic bottles with plastic bottle caps. Three bottles were stored at room temperature, and three bottles were refrigerated at 4°C. Following shaking, a 1 mL sample was taken from each bottle on days 0, 7, 14, 28, and 60. Samples were assayed using the high-performance liquid chromatography method. The samples were visually examined for colour change and separation at each time point. Stability was defined as the retention of at least 90% of the initial concentration. Ethics approval was not required for this research article as it was a stability study that did not involve human subjects.

Results

The clofazimine content remained >94% of the initial concentration throughout the 60-day period for samples that were kept at room temperature, and slightly <90% (87.4%) for samples that were kept refrigerated at 4°C. No separation or colour change was noted throughout the 60-day period for both preparations.

Conclusion

Extemporaneously prepared suspensions of clofazimine in Ora-Blend SF were chemically stable for at least 60 days when stored at room temperature. Clofazimine degraded slightly more rapidly at 4°C compared to room temperature.