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New Process Boosts Injectable Drug Purity, Safety

Drug particles in suspension

Drug particles in suspension, with excess surfactants removed (Jonathan Lovell, University at Buffalo)

20 May 2016. A team of engineers and chemists developed a process for enhancing the purity and safety of drugs given with injections by removing excess additives, while keeping the drugs easy to inject. Researchers from University at Buffalo in New York, led by biomedical engineering professor Jonathan Lovell, describe their process in yesterday’s issue of the journal Nature Communications.

Lovell’s group is seeking an answer to a long-standing need of formulating hydrophobic, or water-repelling drugs for injection, which means suspending minute compound particles in liquids for delivery. In many cases, drug manufacturers use surface active agents, or surfactants, that break down the connection between water, oils, and particles enabling particles to float, or suspend, in the liquid. Some surfactants, however, can cause allergic reactions in some patients, such as blood clots and anaphylactic shock.

Finding alternatives to surfactants up to now meant milling drug particles to nanoscale dimensions, which the authors say works for oral compounds, but for many injectable drugs, particles are still too large or risk contamination from microbes. Other approaches taken by scientists are to start from scratch with entirely new formulations of drugs, which can be time consuming, or use additives other than surfactants to suspend drug particles in liquids that could also induce adverse effects in recipients.

The researchers sought to keep the current process of employing surfactants with injectable drugs, but sharply reduced the amount of surfactant needed, thus creating a safer form of the drug that can still be injected. Their method combines current drug formulations with poloxamer, a biocompatible polymer marketed as Pluronic, used as a dispersant or wetting agent, and approved for pharmaceuticals. The process then chills the drug/Pluronic solution to 4 degrees Celsius (39.2 F). At this temperature, most of the surfactants can be filtered out of the solution through a membrane, leaving frozen drug molecules called micelles with minimal surfactant content, from 100 to 1,000 times less.

The team tested their process with a collection of compounds and biologic treatments given with injections, including common drugs such as cabazitaxel given in chemotherapy, the immunosuppressive drug cyclosporine to prevent organ rejection after transplants, the blood clotting drug phylloquinone also known as vitamin K1, and the male hormone testosterone undecanoate.

Resulting micelle particles ranged from 39 to 165 nanometers; 1 nanometer equals 1 billionth of a meter. In some cases a saline solution was added to prevent the particles from aggregating. The researchers also tested the purified drugs in lab mice for efficacy and dosage levels.

“Essentially, it’s a new way to package drugs,” says Lovell in a university statement. “For the drugs we looked at, this is as close as anyone has gotten to introducing pure, injectable medicine into the body.”

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