Her discoveries facilitate smoother drug intake

Lipids are fats, and fats are found everywhere in the body; the active substance in a drug can mix with the lipid and thus create a drug depot inside the body if the drug is injected under the skin. Through diffusion or breakdown, the body then releases the substance naturally over a longer period of time.

“So instead of taking a tablet every day, you can have an injection and then let the body distribute the substance in a steady flow. Another advantage is that it reduces the side effects of the drug, as it avoids peaks and troughs in the supply to the body,” explains Engstedt.

According to Engstedt, there are already drugs on the market that are released in this way. One example is the active substance buprenorphine, which is used to treat heroin addiction.

Benefit to patients and end-users

"It is a drug that is classified as a narcotic, so instead of going to the health centre every day, you can now get an injection every month and avoid the logistics and distribution.

In the first phase of her thesis, Engstedt focused on the different structures that lipids can form. An interesting discovery was that even very small adjustments to the lipid composition led to major changes in the structure and its properties.

"The lipid consists of a main group and a tail. The tail is hydrophobic (water-repellent), and the main group is hydrophilic, which means that the lipid has an amphiphilic property, that is, it both likes and dislikes water. So, when the lipid comes into contact with water, the tail wants to protect itself from the water. Depending on what the lipid looks like, whether it is cone-shaped or cylindrical, it will try to form a new and specific structure to achieve a lower energy state. We saw that these are very sensitive systems that are easy to adjust. You just need to know which way to do it!”

But according to Engstedt, the most interesting discovery is that the lipid depot is not homogeneous when injected.

“The lipids will move around in the depot itself. So, the centre of the depot will not look the same as the outer layer, which leads to a difference in concentration inside the depot. This is an important discovery for understanding how the platform works.”

Future use

“We now know how it works in vitro; the next step is to put it into practice in vivo. And to be able to regulate the lipid composition there depending on how you want the drug to be released. It also helps Camurus to better understand the formulation and why some compositions work better than others.