Have you ever read the back of your medicine bottle? I have, and honestly it is terrifying. A lot of medicines that I’ve taken have a massive list of potential side effects. I’ve been sick for the past few weeks, so I got put on an antibiotic, doxycycline. It’s been working great for me, but it has a ton of side effects. I’ve had to drink a full glass of water along with my medication and avoid laying down for at least half an hour. If I don’t follow these instructions, I run the risk of getting horrible stomach aches. I have been feeling sick to my stomach at times throughout the week because of my medication. To be fair, I am a hypochondriac, so half the time this was probably all in my head, but still. When I was younger, I used to think, What is the point of taking medication that could potentially make me feel sicker? Why can’t pharmaceutical companies get their act together and create medication that won’t make people sick?
This semester, I learned that it’s not that simple. Most of the time, side effects are caused when the active ingredient is released at the wrong time or at the wrong target. It’s the job of the drug delivery system to regulate when this active ingredient is released. And this isn’t easy. It is difficult to specifically target one organ or cell type in the human body.
In my English Writing course, I looked at liposomal drug delivery systems. These drug delivery systems are pretty much a phospholipid bilayer with some sort of surface modification that will ideally bind to only a specific cell type. Once this binding occurs, the delivery system releases the active ingredient to the proper cells. While the liposome protects the patient from unwanted side effects, it decreases the drug’s effectiveness. In addition, it cannot prevent all side effects.
For my technical report, I analyzed liposomal doxorubicin, also known as Doxil, which is a chemotherapy drug for a third-line treatment of ovarian cancer. The liposome prevented a lot of the cardiac complications that had occurred in patients receiving in straight doxorubicin, but it had a ton of nasty side effects. For example, when the liposomes leaked into capillaries in the hands and feet, it caused severe skin irritation in the patients. To make matters worse, the drug could only extend the life of the patients by a few months!
Through this project, I learned about how difficult it is to design an effective drug delivery system. There are a ton of different surface modification options for liposomal drug delivery systems, but it is difficult to predict how they will perform in vivo. For example, you can attach a target moiety to the surface that will increase the liposome’s specificity. I remember reading one study about scientists who tried to attach a target moiety to a liposomal drug delivery system for a different chemotherapy drug to make sure that the system attached to the proper cells. The target moiety better protected the patient’s healthy cells, but the long chemical groups sticking out of the liposome made it impossible for the liposome to penetrate the tumor.
I learned that when looking at drug delivery systems, there is a ton of compromise involved. And unfortunately, for the drug to actually work, some patients will inevitably experience some side effects. While side effects should be limited as much as reasonably possible, they will always be a necessary evil when it comes to medications.