Excipients are key ingredients in the pharmaceutical industry. Furthermore, the demand for controlled release formulations is expanding, considering the trend of greater comfort linked to the use of drugs. Extended-release products have reduced dosing frequencies, which are particularly beneficial for pediatric and geriatric patients, but are appreciated by most patients and in general lead to improved medication adherence. Reformulation of branded drugs in controlled-release formats is one of the most common methods for extending the product lifecycle. Generic drugs are also often formulated with controlled-release properties.
How controlled release is achieved?
Controlled-release “behavior” can be achieved by using polymeric coatings on solid dosage forms or by incorporating various types of polymer matrix systems, enzyme-activated systems, or systems that respond to changes in physical conditions within of the formulation. Mechanisms include dissolution, diffusion, osmotic pressure, maintenance of a hydrological or hydrodynamic equilibrium and ion exchange. Newer approaches based on nanotechnologies and new matrix technologies are currently under development and include administration of retarded controlled release drugs, floating systems and mucoadhesive systems for the regulated release of antiviral drugs.
The role of the excipients in controlled release
Excipients are key ingredients in controlled release formulations. They contribute to the formation of the matrix in the systems that use it and act as polymeric membranes for powders and multi-particulate systems in the forms of oral solid dosage (OSD). In oral liquid products, the excipients can also provide taste masking and protection for the gastric mucosa. In other specific cases, the excipients can be a deterrent to abuse and help to avoid alcohol-induced dumping. The excipients that provide controlled-release characteristics to oral solid dosage forms not only allow control of the API release rate, but also target the district where the release occurs.