Active Pharmaceutical Ingredients in AIDS Drugs: Using NMR Relaxation to Determine the Wetted Surface Area of Suspensions
Reducing the particle size of materials possessing poor solubility characteristics can be an avenue to substantially increasing the total surface area of the material. This concept can be illustrated when formulating drug products that contain active pharmaceutical ingredients (APIs). A larger surface area allows for much faster dissolution of APIs and, thereby, an increase in bioavailability, regardless of the route of administration. This is of obvious importance in manufacturing because low active bioavailability of drugs can lead to inefficient treatment and risk of toxic side effects. Any increase in efficacy can reduce the potential toxicity because less drug substance is needed, which also serves to reduce costs. There is also a growing body of evidence that, specifically with nanoparticulate API materials, it is the particle surface area and not particle size that is the defining metric that controls toxicological interaction. This explains the recent drive to develop reformulations based on nanotechnology.
So, what technique can make fast, reliable, direct measurements of wetted surface area in any suspension and, particularly, nanosize API dispersions? Nuclear magnetic resonance (NMR) relaxation, which is the basis for Mageleka’s MagnoMeter XRS™, can directly measure the wetted surface area of any particulate suspension.
