Why strong analgesics can make our pain worse


You may never have heard of it, but there is a phenomenon that leaves scientists perplexed, opiate-induced hyperalgesia. It is nothing more than an exaggerated sensitivity to pain, specifically in people who take drugs derived from opium and whose function is precisely to diminish or eliminate pain (among the substances are morphine, methadone, oxycodone, codeine, heroin, etc.).

Some studies around the world try to understand what is going on in the human body to generate this reaction, as the Science website showed.

In a study carried out in Australia, where the person used in the experiment should dipping his hand in ice water, he was able to leave his arm dipped for two minutes. Patients who took methadone, on average, lasted about 15 seconds. At high doses, opioid analgesics increase pain by changing the signals emitted to the central nervous system.

“Imagine if all medications for diabetic patients increased blood sugar instead of decreasing it”, explained Jianren Mao, a pain researcher at Massachusetts General Hospital.

The relationship made by Mao, who studies hyperalgesia in humans and rodents for more than 20 years, is the same as that of opiates. The scientist is one of the few interested in studying the phenomenon, an epidemic of opiate use, much discussed in countries like the United States.

At bottom, extreme sensitivity to pain makes sense, at least for some experts, the human body has the need to feel pain and it must be preserved, as anesthesiologist and pharmacologist Martin Angst of Stanford University explains. After all, for him, nature did not invent pain just to torture us.

His biology attacks back and states that “I’m blindfolded because of all these chemicals. I need to be able to feel pain again”.

This Angst argument makes sense, the pain serves to pull back from a hot stove nozzle or do not move an injured leg while it recovers. In times when it is crucial that we do not feel pain, for example, when our lives are at stake and we need to get out of a situation, the human body itself has a way of recovering by itself, releasing its own opiates that block pain.

Dr. Jianren Mao, MD, was one of the first to investigate hyperalgesia in 1994, and has already identified that the sensitivity in rats was altered depending on the dose of substances they took. In the 2000s, with doctors considering it safe to prescribe and administer opiate medicines for chronic pain, Mao went on to pay special attention to the growing patient population.

Over the past two decades, the number of deaths from opioids prescribed in the United States has quadrupled to 21,000 in 2014, overdoses have increased as well as revenues, and there are still those who use recreational substances such as heroin in high doses. Opiates can kill, especially when combined with alcohol or other drugs.

“I do not know if you can consider yourself exemplary, a doctor who is doing worse to humans than we have achieved with the liberal way of prescribing opiates,” said David Clark, an anesthesiologist at Stanford.

The hyperalgesia investigated by Mao can be guilty of these deaths. People may look for larger doses as their pain worsens, and the doctor increases the dose, when the correct dose should be to decrease it.

The number of people who have opiate-induced hyperalgesia and the dose taken from this medicine are still uncertain. By involving tolerances, the phenomenon is difficult to diagnose and control.