This article discusses the development of highly structured membranes for constant release of therapeutics over a broad range of molecular sizes, at release rates relevant for medical applications. In the experimental study, the constant release was achieved with small molecules such as leuprolide, a common treatment for prostate cancer, as well as with large molecules such as bevacizumab, widely used in the treatment of metastatic colon cancer. Such an approach could be applied to achieve the goal of metronomic delivery of chemotherapeutics, a constant low-dose administration of drugs over a long period of time. By exploiting nanochannels in passive systems, researchers were to achieve a controlled and constant delivery for extended periods of time, mimicking the basal and continuous flow of molecules from natural glands. This functionality cannot be attained at the macro- or microscale without the use of complex pumping devices and other moving components, because the diffusion of molecules is Fickian, meaning that the release rate is dictated by the gradient of molecular concentration.
Intravaginal rings for continuous low-dose administration of cervical ripening agents