SC V C. Bioequivalence of Oral Liquids

Patients receiving medicines with a low therapeutic index may require their blood levels to be monitored to ensure they remain within the required therapeutic range. This therapeutic drug monitoring is essential for substances such as those used for anticoagulant or neuroleptic therapy, because of the potential for non-bioequivalence between different products, and is particularly important in the case of unlicensed oral suspensions.

Where the medicinal products are licensed, appropriate information will be provided in the Summary of Product Characteristics (SmPC) and/or in the Patient Information Leaflet (PIL). No such information will be provided, however, for unlicensed medicines.

It is possible that different formulations of oral suspensions may not be bioequivalent, particularly if the particle size of the active ingredient in the formulations is significantly different. Differences may occur between batches of the same product from a single source or between formulations from different sources.

For unlicensed oral solutions and suspensions of pharmaceutical substances where bioequivalence is a concern and therapeutic drug monitoring is a routine practice, the following statement has been included in relevant British Pharmacopoeia monographs:

“Patients should be monitored in accordance with appropriate clinical guidelines.”