Since a change in the law a few months ago, doctors have been able to prescribe cannabis medicines on prescription in justified individual cases. This is intended, for example, for certain patients with multiple sclerosis, nerve injuries or rheumatism. In the run-up to the German Pain Congress (October 11-14, 2017), experts are now warning that the effective effectiveness of cannabis-based medicines has so far only been proven in a few diseases with chronic pain.
Cannabis law in force since March 2017
In March this year, the “Cannabis as Medicine” law came into force. This regulates the use of cannabis-based drugs as an alternative therapy. In certain individual cases, seriously ill patients can receive cannabis with a prescription if, for example, they suffer from chronic pain, multiple sclerosis or if they have anorexia due to AIDS or cancer. The prerequisite for such a prescription is that, in the opinion of the treating doctor, a positive impact on the course of the disease can be expected.
Experts advise against self-therapy
Six months after the change in law came into force, however, the German Pain Society e.V. and the German Migraine and Headache Society e. V. (DMKG) pointed out that a positive effect of cannabis medication was only proven in a fraction of the illnesses with chronic pain. As the German Pain Society e.V. explains in a current press release, the experts expressly advise against self-therapy with cannabis flowers. Since the dosages would be inaccurate, there could be undesirable adverse health effects.
"There is insufficient evidence that cannabis-based drugs are effective in the treatment of tumor pain, rheumatic and gastrointestinal pain or loss of appetite in cancer and AIDS," said Professor Winfried Häuser, medical director of the Psychosomatics Department at Saarbrücken Clinic, according to the announcement.
Efficacy only proven for neuropathic pain
Hauser and his colleagues came to this conclusion after evaluating eleven systematic overviews from a total of 750 identified studies on this topic, all of which were published between January 2009 and January 2017. The work published in the Deutsches Ärzteblatt shows that the benefits of cannabis-based drugs such as e.g. Dronabinol, nabilone, or THC / CBD spray for tumor pain, rheumatic and gastrointestinal pain could not be adequately demonstrated empirically. Likewise, according to the scientific evaluation, no positive effect in case of loss of appetite due to cancer and AIDS can be proven.
The only exception is the so-called nerve pain, which is caused by damage or diseases of the nervous system. "A sufficient quantity of evidence is only available for neuropathic pain," adds Häuser.
Expert warns of cannabis for headaches
"Cannabis as a pain reliever has been in vogue since the law was changed in March," said the President of the DMKG, Dr. Stefanie Förderreuther. As a result of the intensive media coverage of “cannabis on prescription” for chronic pain, patients would sometimes vehemently request a prescription from their doctor even for headaches, explains Förderreuther. But even in this area, the study situation would not be sufficient to recommend regular treatment with cannabis-based drugs.
“We need studies to prove that one or more cannabinoids are not only effective in treating defined headache syndromes, but above all they are safe. In contrast to all substances approved for the treatment of headache, the corresponding data is missing, ”emphasizes the senior physician at the Neurological Clinic at Ludwig Maximilians University. The expert therefore warns above all of a hasty prescription of a cannabis drug for headaches and migraines.
As the German Pain Society reports, the female hemp plant Cannabis sativa contains around 500 different components, including around 100 cannabinoids. The medical effects of two cannabinoids (tetrahydrocannbinol and cannabidiol) in relieving pain and inflammation have been proven in individual cases and by some clinical studies - the effects on the human body, however, are largely unexplored, according to the experts.
"First of all, randomized, placebo-controlled studies that are methodologically well-made must be available for each clinical picture, which demonstrate the desired effect of pain relief and record the type, severity and frequency of side effects such as confusion or psychosis," emphasizes Förderreuther.
14 types of cannabis flowers available
It is also important to differentiate between different forms of cannabis-based medication. In the currently 14 varieties of cannabis flowers available on prescription (“medicinal hemp”), the concentration of the tetrahydrocannabinol (THC) contained is between 1 and 22 percent and that of cannabidiol (CBD) is between 0.05 and 9 percent. This would make it more difficult that there are no dosage information for individual indications, the expert warns.
Warning of self therapy
Despite all the criticism and warnings, the German Pain Society still welcomes the new law. The change now regulates the reimbursement of costs for prescription and finished medicinal products containing cannabis. However, it is important that this “not as an isolated therapy method, but in combination with physiotherapy and
pain psychotherapeutic procedures are used, ”demand houses and Förderreuther. The experts, on the other hand, generally reject self-therapy due to unpredictable side effects due to inaccurate dosages. (No)