Physicochemical Evaluation of Compounded Oral Preparations for Respiratory Illnesses, also known as Mezclitas

Compounded oral solutions for respiratory illnesses such as the common cold and cough are commonly prepared and dispensed by licensed pharmacists in the United States and Puerto Rico (PR). Standard protocols for their preparation and quality assessment and for patient counseling are available for most of the prescribed compounded solutions. However, in PR there is a common prescription approach colloquially referred to as "mezclitas": mixtures of antitussives, expectorants, decongestants, and other active ingredients available in commercial solutions for which there are no science-driven compounding guidelines for local pharmacists.

This study evaluated the physicochemical stability of a commonly dispensed compounded preparation (containing guaifenesin, dextromethorphan, and dexamethasone) that is used for the treatment of respiratory illnesses in PR. The stability indicators tested included clarity, odor, pH, and viscosity. Changes in stability indicators were evaluated for different storage conditions (ambient temperature and refrigerated) over a period of 6 months.

The samples exhibited small changes in color, odor, and viscosity. Although the observed changes were small, they may be indicative of chemical and/or physical transformations that occurred over time. A survey of local pharmacists also evidenced the absence of standardized protocols for the preparation and dispensation of the mezclitas in PR.

In spite of the absence of protocols for compounding oral solutions for respiratory illnesses, our study suggests that the stability of such solutions is not heavily compromised. However further chemical and physical testing is needed and the findings of such testing used to develop standardized protocols for the compounding of oral solutions for respiratory illnesses.