Controlled Drug Release Technology of Drugs

The concentration of medications released from polymeric matrices should be within the therapeutic window with little variation in blood lev...

The concentration of medications released from polymeric matrices should be within the therapeutic window with little variation in blood levels over extended periods of time at the targeted site of action in order to accomplish effective disease management.

Diffusion, erosion, osmotic-mediated processes, or mixtures of these mechanisms may be used to regulate the release of a medication. In most cases, a triphasic release pattern is seen, with the first phase primarily attributable to drug precipitates at the particle surface and surface pores in the polymer, as well as to osmotic forces in formulations of highly water-soluble peptides, followed by a lag phase depending on the molecular weight and polymer end-capping, and finally erosion-accelerated release.

When release rate control is taken into account, a smaller particle (one with a greater specific surface area) leads to a higher release. Additionally, bigger inner surfaces caused by increased porosity in the particles can enhance the inflow of the release medium into the particles and speed up the rate of drug diffusion. The drug release rate will also be greatly influenced by the unique characteristics of the polymer matrix, such as the chain length, flexibility, and swelling behavior, as well as any potential interactions between the polymer and the drug. Therefore, changing to a polymer with an end group cap or a different molecular weight, as well as using block copolymers, will affect the diffusion and drug release rate.

A mix of fast- and slow-releasing particles or the usage of copolymers are potential alternative advanced ways for achieving zero-order release kinetics indicative of uniform release with regard to time, which is sought for the majority of applications. By co-injecting a bolus of soluble medication as a loading dose and zero-order releasing microspheres as a maintenance dosage, a single dose may be administered.