The NCL has just added a new protocol to our Assay Cascade Protocols page to measure drug release from nanomedicines. The protocol, PHA-2, is based off of the recent Journal of Controlled Release publication, Stable isotope method to measure drug release from nanomedicines. Since its publication in late 2015, this assay has gained a lot of attention and has been in high demand at the NCL, particularly in regards to bioequivalence analysis of follow-on/generic nanomedicines. The unique features of this assay include:
- Can be done in biological matrix, either in vitro or using samples from an in vivo study
- Can determine encapsulated, protein-bound, and free unbound drug concentrations
- Utilizes a stable isotope of the drug, many of which are commercially available
- No requirement for radioactivity (like NCL protocol PHA-1)
The protocol uses a stable isotopically labeled version of the drug (D*) and a simple ultrafiltration technique. When spiked into plasma or other matrix, D* equilibrates with protein (Pro) and nanomedicine (NM) identical to the unlabeled, normoisotopic drug (D). Therefore, the ultrafiltrate fraction of the isotopically labeled drug represents a reliable measurement of the free drug fraction. The plasma protein bound, unencapsulated and encapsulated nanomedicine fractions can then be easily calculated.
Have questions on the protocol? Let us know. Dr. Stephan Stern, developer of the technique, will be happy to address questions.