CAUTION with metamizole [Novalgin, Novalminsulfon u.a.]

Metamizole, better known under the trade name “Novalgin”, belongs to the group of non-acidic non-opioid analgesics. The parent compound has no significant effect. Rather, the metabolization/cleavage of the sulfonate group and its methylene groups result in metabolites that have an analgesic effect.

Exactly how these metabolites work has not been clarified to this day, although the substance is not one of the newer drugs (“discovered” and put on the market in 1922).

Perhaps this ignorance is also a symptom of the fact that the substance is judged differently around the world. While in most German-speaking countries the drug can sometimes even be obtained without a prescription, in many other countries, such as the USA, Great Britain, etc., it has completely disappeared from the market. A major reason for the ban on the drug market in these countries is the increased incidence of fatal agranulocytosis.

In general, the substance seems to have a “preference” for blood-related side effects (aplastic anemia, porphyria, but also Lyell’s syndrome, anaphylaxis, bronchospasm, etc.).

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Pregnancy and lactation are among the absolute contraindications. Elderly patients and patients with impaired liver and/or kidney function should only take small doses of the substance. This should be done under close supervision. Patients with a medical history of the side effects listed above should not receive the substance. The same applies to children weighing less than 16 kg.

There are also a number of drug interactions such as anticoagulants, lithium, captopril and other antihypertensive drugs.

The list of countries that have taken the substance off the market or not approved it at all is not exactly short: Sweden, Norway, Denmark, Iceland, Greece, Great Britain, Ireland, Australia, Japan, USA and since 2013 India. The reason for these restrictive measures was the relatively high rate of agranulocytosis (often fatal).

Hoechst, the original manufacturer of the substance, undertook a “scientific” effort as early as 1986 to describe the risk of developing agranulocytosis with the medication:

The company’s study, which does not list authors (hardly a sign of the highest degree of scientific excellence, but Hoechst “science” at best), concluded that the incidence for this side effect is 1.1 in every 1 million uses per week.

In the meantime, this study is considered irrelevant, since it was supposed to conjure up a “scientific” Persil certificate for its own product with the correspondingly distorted methodological means. Epidemiological studies in Sweden identified a risk of 1 per 1439 prescriptions. The “Arzneimittelbrief” is interesting in this regard: How dangerous is metamizol?

However, the resistant handling in many countries and the refusal of approval in other countries does not prevent the industry from praising its own product with its own, typical “scientific” means and branding restrictions as bias and prejudice:

This time it is the Boehringer Ingelheim company, which, in conjunction with medical universities in Germany and the USA, comes to the conclusion that all studies that have come to a negative result for the substance are far too small and were led by economic(?) interests.

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Online guides such as Onmeda.de, on the other hand, praise the good effectiveness for pain (which was never doubted), but advises careful use of the substance:

“The active ingredient is often used as a reserve. That is, patients receive metamizol when other measures have not been successful.”

However, this is the case for patients who suffer from extremely severe pain after surgery or cancer. Fever, against which metamizole also works well, is by no means a primary indication for the substance. There are much more tolerable alternatives.

As to the question of whether children can be treated with metamizole, I had already given a “hint” above. The source is the “Information for professionals (summary of product characteristics) Novaminsulfon injekt 1000 mg Lichtenstein Novaminsulfon injekt 2500 mg Lichtenstein“ by the company Winthrop Arzneimittel GmbH, which is quoted in the English-language Wikipedia edition, but whose link is no longer active. According to this information, children with a body weight of less than 16 kg should not be treated with metamizole.

In 2009, the “Ärzteblatt” published an article that addressed the use of metamizol in children, but not very positively for the substance: Pain therapy in children and adolescents: advise against metamizol. This article by a professor of toxicology at the University of Wittenberg is a response to an article in the “Ärzteblatt” that was positive about metamizol and recommended intravenous metamizol for babies as young as 3 months old. When asked about conflicts of interest, the writer of the positive article turned out to be a well-paid “rental” from a number of pharmaceutical companies.

Conclusion

Metamizol is at best a third-line pain reliever when all else fails. The torn discussion about whether it’s safe or not is once again a prime example of how the pharmaceutical industry and its protagonists are trying to whitewash a top-selling product with lazy “science”.

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