Professor Wunder, what options are available when it comes to administering drugs to patients these days?

In general, we doctors have a vast range of options at our disposal – almost all the pathways into the human body can be used. There’s the skin, of course, through which active agents can be absorbed. We can apply patches which allow substances to be administered continually over a lengthy period. Intramuscular injections are also used to administer drugs – the majority of vaccinations are delivered in this fashion. The entire digestive system, from the nose and mouth via the esophagus all the way to the gastrointestinal tract, is a particularly popular pathway for medication: every pill swallowed enters the body this way. We anesthetists are used to puncturing blood vessels in order to establish vascular access and deliver drugs directly into the bloodstream. Then there are also inhalers for the lungs, special needles for epidural anesthesia in the spinal cord area, suppositories for rectal use, and vaginal drug administration. Special drug delivery systems exist for all of these pathways.

What determines which pathway and delivery system you use?

On the one hand, the nature of the drug itself has a crucial role to play. What are its molecular properties? How is it metabolized? Is it supposed to take effect gradually or immediately? Specific drugs for specific indications have to be injected directly into a vein, while others can be administered in the form of a tablet. But another factor is increasingly taking center stage when it comes to determining the choice of delivery system: patient freedom.

So, it’s a question of whether patients can administer the drug themselves?

Yes, and it’s a very important point. Patients who are independent and healthy enough should not need us to help administer their medication in the long term. This objective is shared by us all – doctors and patients alike – and is the reason why most of the developments in the field of drug delivery systems are tending in this direction. The idea is to combine active agents with other carrier substances in a way that allows medication that could previously only be administered by injection to be delivered orally as well. Tablets, for instance, are now frequently made in wafer form, enabling the active agent to be absorbed quickly through the particularly permeable oral mucosa.

What about active agents that cannot be administered orally as yet?

In the case of some active agents, systems are now available that increasingly render injections – even if that merely involves puncturing the subcutaneous adipose tissue – superfluous. I’m thinking about implantable insulin pumps, for example. These tiny high-tech portable works of art dispense insulin around the clock to make people’s lives easier. That brings us to another important direction that is the subject of research: enhancing patient convenience. The simpler and less unpleasant the form of administration, the better. What’s more, increasing the level of personal patient responsibility is resulting in greater independence. Hospital patients suffering pain once had to call a nurse every time they required a dose of opioids. Now they are given a pump and can administer the drugs themselves, as and when they need them.

Where do freedom and individual responsibility come up against their limits?

The biggest risk is that a patient will administer too high or too low a dose by mistake. When it comes to new drug delivery systems, the issue of safety is therefore always a prime consideration. There are pill boxes with compartments that only open at the right time of day, applicators that only allow as many pills to be popped in the mouth as are required at the time, and morphine pumps that do not release another dose for a defined period once a certain amount has been dispensed. The question of safety, by the way, is not restricted to drug delivery systems for self-administration: it also applies to medication administered by doctors.

What attempts are being made to increase safety in this area?

Epidural catheters, for instance, which require much lower doses than venous catheters, have their own attachments that don’t fit onto venous catheters. This makes it much harder to confuse the two. And of course, the increasing use of networking and digitalization makes for greater safety and enhanced administration control: these days, many administration systems are linked directly to the hospital’s data management system, enabling drug delivery to be recorded automatically in a patient’s digital medical records. It’s a real boon, as it saves us having to deal with the documentation and reduces the error rate.

So, further developments in drug delivery systems make doctors’ work easier and provide greater safety for patients.

That’s one way of summing it up. But nevertheless, all progress is ultimately guided and determined by one question: how do I get a specific concentration of a specific active agent to the target site in the body as directly as possible and without any side-effects?