The oral administration of drugs is a tried and true method that is widely favored by patients and healthcare providers alike. Despite the pros of oral drug administration, such as cost-effectiveness and patient compliance, it is not necessarily the most effective method of drug delivery. As such, scientists have attempted to develop more effective drug carriers for use in oral administration, including polymeric micelles. In their work, featured in the Journal of Polymer Science, Part A: Polymer Chemistry, Puja Das Karmakar and colleagues furthered the research that seeks to optimize these micelles for effective and efficient drug delivery while maintaining the convenience of oral administration.
(a) The in vitro cumulative drug release of NFD-loaded micelles with respect to time and (b) a schematic diagram of the drug release from the copolymeric micelles
Karmakar and colleagues chose nifedipine (NFD), a hydrophobic drug used to treat high blood pressure and angina, to test the novel polymeric micelle they synthesized. The team synthesized the pH-responsive supramolecular graft copolymeric micelle from dextran and poly (oleic acid) through a process called reversible addition fragmentation chain transfer (RAFT). Various copolymers with poly (oleic acid) have been studied before, but the combination of dextran is unique. Dextran was chosen by the team because of its hydrophilic and biocompatible nature, and conjugating it with the hydrophobic poly (oleic acid) results in the formation of copolymeric micelles that can encapsulate NFD.
Some drugs are hydrophobic and cannot reach their targeted sites through the gastrointestinal (GI) tract, a difficulty that influences both the effectiveness of the drug and the potential toxicity of the “free” drug. Using a delivery system such as polymeric micelles helps to overcome this issue by carrying the drug intact to the correct site for targeted release. Polymers that are stimuli-responsive, such as to pH, are good options for use in drug delivery systems since different areas of the body possess different pH values.
The team tested the nature of the polymerization, thermal stability, morphology, loading efficacy, and release characteristics of the novel copolymeric micelle they synthesized. They found that the copolymeric micelle studied here had good loading efficacy and demonstrated different rates of NFD release at the different pH values of gastric fluid and intestinal fluid. The synthesized copolymeric micelles allowed for more targeted delivery of the hydrophobic NFD to its intended site, thus reducing the chance of side effects.
The team hopes that, in the future, the copolymeric micelle they have synthesized can be used for the increased efficacy of other hydrophobic drugs administered orally.
