Researchers have developed a new method to measure the release of drugs over time, using a simple method.
OxyContin, containing the opiate oxycodone, was intended to offer 12-hour pain relief. Instead, in some patients it dissolved much more quickly, causing them to take it more frequently and ultimately become addicted. But assessing how a drug dissolves in the body is surprisingly tricky. Drug dissolution has to be measured under laboratory conditions that come as close as possible to mimicking what happens in the body.
Corresponding author William Grover, associate professor of bioengineering at the Marlan and Rosemary Bourns College of Engineering explains: “We directly measured dissolution profiles of single drug granules, which are the little spheres you see when you open up a capsule. We accomplished this using a vibrating tube sensor, which is just a piece of glass tubing bent in the shape of a tuning fork.”
Many factors influence the way a drug is dissolved in the body, such as the chemical composition and pH of the fluid, the patient’s sex and their metabolism. Meals taken also have a strong impact: taking a fatty meal increases the amount of oxycodone released from OxyContin by 25%.
Pharmaceutical companies simulate these conditions in test vessels to build a profile of how the drug works over time, but this has its drawbacks. The position of tablets in the vessels can affect dissolution rates; equipment can become clogged; the process is very time-consuming and they only provide brief snapshots over time.
The new approach takes a radically different approach, measuring the mass of a drug granule as it dissolves. This is accomplished by changes in the resonant frequency, which can be measured over time instead of being sampled.
Using the technique on three proton-pump inhibitors, the researchers found considerable variations between name-brand and generic formulations of the drugs, affecting the rate at which the drugs are absorbed by patients.
“Our technique is much cheaper and easier to perform than conventional methods, and that enables pharmaceutical companies to do more tests in a wider variety of conditions,” said Grover. “We can also easily see differences in dissolution between individual particles in a drug. That should help pharmaceutical companies improve and monitor the consistency of their manufacturing processes.”
Source: Medical Xpress
