Renger Witkamp: “Cannabis is constantly making fun of us”

Biologist and pharmacologist Renger Witkamp is a professor of Nutritional Biology at Wageningen University & Research (WUR). Since 2005, he has also been professionally interested in the (im)possibilities of cannabis as a medicine. He has been involved in research into the medicinal effect of cannabis for over twenty years and also chairs the Institute for Medicinal Cannabis (IMC) in the Netherlands since spring 2021. As he notes, “the development and sharing of scientific knowledge about cannabis is a priority.”

Food and pharmaceuticals

Renger Witkamp constantly balances his work at the intersection of food and pharmaceuticals. He once described his field as ‘the field of science concerned with studying the effects of biologically active substances in food, with the aim of achieving a health-promoting or curative effect.’ According to Witkamp, ​​the key to a good and healthy life is a ‘healthy lifestyle’ and it is now generally known that nutrition plays a crucial role in this. But sometimes adjustments are necessary and pharmacology can offer a solution. And Witkamp and his team look further than just regular medication, because the department also focuses on herbs with a proven or alleged medicinal effect. Cannabis is one of them.

No panacea

Witkamp’s interest in the medicinal use of cannabis does not come out of the blue. “I was trained as a pharmacist, I studied biology, and I have always been interested in medicinal herbs. Precisely because the medicinal use of some herbs has been known worldwide for centuries, but often no scientific explanation has yet been found. Cannabis is definitely one of the most interesting plants, especially when you look back in history. The plant has been used for medicinal purposes for centuries and since the late last century, when the endocannabinoid system (“ECS”) was discovered, interest has been rekindled – and rightly so. But cannabis is certainly not a panacea and we still need a lot of scientific evidence to make well-founded statements about how it works.

The problem is that cannabis – with all its different substances – is not an easy ‘product’ to research scientifically. The plant is constantly making fun of us. Cannabis is full of all kinds of substances, of which we only know a small part of what they do. And if we want to conduct research, which condition should we choose? In addition, we are not yet sure which formulation, which dosage form, and which dosage is best. In short, there is still a lot of scientific work to be done.”

Scientific research

Witkamp has certainly contributed to scientific research. Since 2005, when he worked at TNO Pharma, he was involved in the analysis of THC in preparations and research into cannabinoids as a painkiller and appetite-stimulating or – inversely –inhibiting substance. “We already knew that there are cannabinoids (phytocannabinoids) in the plant, but now we also knew that similar substances (endocannabinoids) exist in the human body. Incidentally, also in many other organisms; we even found them in worms…

Like other researchers, we want to know how these phytocannabinoids affect the ECS. I remember that around 2006 all eyes were on the function of CB1 receptors in the body, which are involved in, amongst other things, the regulation of appetite and the development of diabetes. Many researchers – including Big Pharma – went in search of a suitable new CB1 blocker in cannabis, because that would mean a breakthrough in the search for the ‘new generation of drugs’. The idea behind such a synthetic blocker of the CB1 receptor was that it seemed to not only inhibit appetite, but such drugs also seemed to work in other ways against diabetes and its associated complications (collectively referred to as ‘metabolic syndrome’).

Ultimately, this was not successful, because such substances turned out to have serious side effects, precisely because the ECS is so complex and plays a role in so many processes in the body. Interestingly, the cannabis plant also contains a CB1 blocker, in amounts depending on the variety, which may seem more interesting in this regard. This is THCV. Big Pharma subsequently dropped out, but the indications that the ECS offers in the field of appetite and pain and other disorders are still there. Meanwhile, research in the field of phytocannabinoids in many different disorders continues, so that has not stopped. We are also continuing research at WUR, as we recently started in collaboration with the National MS Fund. Together with them, and a number of other parties, we will investigate what CBD can do for MS patients with sleeping problems. But we also see interesting research programs in, for example, Leiden (chronic pain, replacement of supplemental opioids) and Groningen (liver cancer).”

Dutch medicinal cannabis program

Renger Witkamp also witnessed first-hand the introduction of the Dutch medicinal cannabis programme, which, from 2003, has provided patients with medical prescription cannabis that has been standardised and produced to pharmaceutical grade. “That was an important step, which has also been taken in several other countries. Especially because strict demands were placed on the product from the start. In addition, the way in which patients can obtain it is well regulated. The route via prescriber and pharmacy is the most appropriate for patients, because both the doctor and pharmacist are watching, while the quality of the medicinal cannabis is guaranteed. This brings me to another important point of attention, and that is pharmacovigilance. It is extremely important that any side effects are documented, because we now know that cannabis is not necessarily harmless. For top fit people that may not matter that much, but for people with a reduced resistance – patients, that is – vigilance is required. In addition, priority will have to be given to smart formulations of cannabis-based medicines and, as mentioned, we must continue with scientific research.”

Cannabis is not necessarily harmless

In the past plus twenty years, Witkamp has seen the world of medicinal cannabis constantly change, but in 2021 he can draw up a balance. “Cannabis is still loaded. Governments are cautious, and so are prescribers. There is still a lot of activism and often the dividing line between medicinal and recreational use is razor thin. All kinds of things are said about the plant, without there being any evidence for it. That’s fine, because traditionally a lot of knowledge comes from the ‘recreational’ angle. But sometimes things are said that could be dangerous for patients, because cannabis, as I said, is not necessarily harmless. I want patients to choose the right route; that they do not start ‘doing’ themselves, but get information and help in the right place; with their doctor, specialist, and pharmacist. But I also want to focus on prescribers because we know that knowledge about medicinal cannabis is sometimes lacking and patients are referred to the coffee shop.”

Share knowledge

With that in mind, Witkamp said ‘yes’ earlier this year when he was asked to become chairman of the IMC, a Dutch foundation that combines all scientific, medical, and production technical knowledge and experience in the field of medicinal cannabis. The foundation, which officially started on 1 March, consists of various organisations, including pharmacists, scientific institutions, universities, and manufacturers. And all affiliated organizations have a common DNA, according to Witkamp: “We are all legally active with medicinal cannabis. All participating organizations have an exemption to work with or conduct research on medicinal cannabis. In addition, we put the patient and the prescriber at the center of all our activities. Combining and expanding the knowledge about medicinal cannabis, and good scientifically based information and discussion about it are matters that are close to my heart and that is exactly what we want to do with the IMC.”