The Ministry of Health has issued a serious warning about the misuse of metamizole -An analgesic whose best known trademark is Nolotil- for the risks entailed by its most dangerous side effect: agranulocytosis. This disorder, which can be deadly, it consists in a sudden fall of the defenses that, in addition, "appears in a random way, that is to say, it does not depend on the dose and in each person the reaction is different", explains Pedro J. Ibor, coordinator of the pain group of the Spanish Society of Primary Care Physicians (Semergen).
The most affected are the elderly and those with a depressed immune system. Although there are no studies that endorse it conclusively, many physicians from Spain and northern Europe suspect that people from these countries have a greater sensitivity to metamizol than Spaniards.
British media reported last weekend that a dozen UK citizens have died after taking metamizol in Spain. This analgesic, one of the most consumed in Spain and Latin America, is not sold in other European countries because of its adverse effects.
The Spanish Agency of Medicines and Health Products (Aemps) issued a note last 30 in which he recalled that metamizol is a drug that can only be sold with a prescription, something that contrasts with the usual practice in most Spanish pharmacies, which sell without it.
The Aemps insists that the drug should only be taken in "short-term treatments, seven days maximum" and that "if a longer treatment is necessary, [es necesario] perform regular blood tests "to monitor the level of white blood cells, which is why the agency recommends" not using metamizole in patients in whom it is possible to perform these controls ", like tourists.
The note also urges "to take special precaution in case of elderly patients," adds the information note. "The elderly are patients who already tend to have lower defenses than the general population, so we have to be very careful with them," Ibor explains.
For more than a decade, the scientific literature has included descriptive studies on cases of agranulocytosis in tourists from northern Europe who have taken the drug in Spain or Latin America. The oldest one that this newspaper has had access to dates from 2002 and analyzes the adverse effects suffered by Swedish citizens – countries in which the drug was withdrawn from the market in 1974 – in Brazil.
In Spain, in 2009, professionals from the Costa del Sol Hospital in Marbella published another study. About 30% of the activity of the center is to citizens of northern Europe due to tourism and the residence of many foreigners in the area.
"We came across it by chance," explains Vicente Faus, co-author of the work and who was then head of the Costa del Sol pharmacy. "The hospital had a computer system that allowed us to investigate the cases of agranulocytosis that we had attended. We wanted to see the real incidence related to metamizol, and our surprise was discovering that among foreigners it was almost triple that among Spaniards, "recalls Faus.
The study concluded that "agranulocytosis by metamizole is an adverse effect that occurs more frequently in the British, so its use should be avoided." Faus points out that "it was a first recommendation pending more studies on the phenomenon."
The Aemps states in its recommendation that "although a greater susceptibility has been discussed for years" among the "population of northern Europe and certain genetic factors have been studied, with the available information can not rule out or confirm a higher risk in populations with specific ethnic characteristics. "
A spokesperson for Boehringer Ingelheim, manufacturer of Nolotil – although there are many generic presentations – explains that "agranulocytosis is a rare adverse effect that only occurs in one in 1,000 to 10,000 patients." "We are working closely with the Aemps to report the effectiveness and safety of the drug," adds this spokesman.