Interview with Prof. Wolfgang Jost

In his presentation at the TOXINS 2019 convention in Copenhagen, Prof. Jost (Parkinson-Klinik Ortenau, Germany) covered the topic of hypersalivation. Last year, incobotulinum toxin A was the only botulinum toxin preparation in the USA to receive approval for sialorrhea without restrictions on the underlying cause.

Are neurotoxins the gold standard for treatment of patients with sialorrhea? Would you also recommend any other drug? Botulinum toxin injections are most likely the most efficacious and the least side effect-associated therapeutic option. Anticholinergics such as glycopyrrolate may also be used but are currently not approved and are, of course, associated with side effects due to their systemic effects.

Did it take long to enroll 184 patients when initiating the SIAXI trial or is sialorrhea a rather common phenomenon? Sialorrhea is a common symptom, particularly in patients with Parkinson’s disease. Recruiting patients was never a problem because the afflicted suffer tremendously. Due to the extraordinary therapeutic success, patients willingly participated, staying on to the end of the study.

How long does it take until one learns the injection technique? What is the greatest danger (worst side effect) of a poor injection technique? The injection technique is easy to learn. Thanks to ultrasound guidance, the salivary glands can be well identified. The main problem of poor injection technique would be a lack of efficacy. In case of targeting the submandibular gland, there would also be the potential danger of dysphagia. With ultrasound guidance, however, this shouldn't happen.

When targeting the submandibular gland, you recommended longer needles in older patients. What is the reason? The anatomy of the neck varies considerably. In people with slender and long necks as well as firm connective tissue, the submandibular gland lies very superficial. As time goes by and the patients get older, the distance between skin and gland might get wider, thus requiring a longer needle.

In the SIAXI study, both ultrasound guidance and anatomical landmark guidance revealed similar outcomes. Why do you personally prefer ultrasound? The fact that there were no differences between ultrasound and anatomical landmark guidance, confirms the safety of the method. It could, however, also be based on the fact that the clinicians were skilled. In general, I use ultrasound guidance when injecting to be sure that the injection ends up where it belongs. It is not all about avoiding side effects, but also about achieving an effect.

What happens in case of unilateral injections? Couldn't that be generally done to prevent side effects such as dry mouth? Or do you always have to inject bilaterally? I would generally suggest bilateral injections. Dry mouth was not an issue in the study and it is not in clinical practice. If less of an efficacy is desired, it is rather recommended to use a lower dosage, distributed into the four most important salivary glands.

There are several serotypes of botulinum toxins. Have other botulinum toxins ever been used to manage intractable sialorrhea? Other botulinum toxins are also used for treatment of sialorrhea, some in trials, too, however, not in controlled approval-relevant studies. The newest botulinum toxin has not yet been investigated in sialorrhea, it first has to prove superiority when used for the classical indications. Whether other botulinum toxins are superior to incobotulinum A remains to be determined and is subject to further investigations. However, there is no urgent need because the current neurotoxin is highly efficient with an efficacy that is sufficiently long lasting.

At this year's election, you became a member of the board of directors of the International Neurotoxin Association (INA). What will be your tasks in the next four years until your term ends in 2023? What are your personal goals you want to achieve as director? I am sure that we will see enormous dynamics in this sector in the next few years. Development of innovative toxins, modified botulinum toxins, respectively, will offer new possibilities. At the same time, we have to protect us against botulinum toxins of poor quality. Development in research provided us with many new insights which will eventually be internalised in our therapies. A huge problem seems to be the promotion and encouragement of new talent, of both young researches who are willing to work as scientists and of clinicians who are willing to treat the numerous patients who can benefit from botulinum neurotoxins.