Hydroxyethylcellulose as a versatile viscosity modifier inthe development of sugar-free, elegant oral liquidformulations

Pharmaceutical formulations in liquid form for oral administration are commonly utilized for geriatric and pediatricpatients who have difficulty swallowing solid dosage forms. Rheology, texture, and stability are among the Critical Quality Attributes (CQAs) that must be addressed in the development of oral liquid dosage forms. The distribution of pharmaceutical components relies on the manipulation of rheological properties and stabilization within these forms. The utilization of thickening agents to increase the viscosity of the liquid vehicle serves to reduce particle settling. Historically, sugars such as sucrose were utilized for this purpose, as well as for masking the taste of activepharmaceutical ingredients (API). However, alternative thickening agents such as xanthan gum, tragacanth, carrageenan, and cellulose derivatives (such as sodium carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxypropylcellulose and hydroxyethylcellulose etc.) are increasingly employed asthey do not possess the same risks of glycogenic and cariogenic as sugars. Cellulose derivatives, due to their water binding and viscosity modifying properties, can be effectively utilized to enhance the rheological properties andstability of oral liquid dosage forms. The use of hydroxyethylcellulose, a highly water-soluble cellulose ether polymer, as a viscosity modifying agent, as well as its underlying polymer chemistry, is thoroughly examined in thisliterature review. Keywords: Cellulose Derivatives; hydroxyethylcellulose; oral Liquids; Natrosol™ 250 HEC, syrup