Biology Question #2347

Gillian, a 17 year old female from Haliburton asks on November 3, 2004,

What effect do pain killers have on the human brain? How exactly do they work? What about drugs like Ritalin or Prozac?

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The answer

Barry Shell answered on November 3, 2004

Different pain killers and drugs work in different ways. The brain has a lot things going on. There are millions of chemical reactions that happen in between nerve cells connecting one cell to the next. Drugs get involved in this chemistry and that is how they work. In some ways, scientists do not know for sure exactly how these things work. Each one is different. Each drug works in a different way and sometimes in multiple ways. Scientists know about how some of it works, but not all of it. You should use to look up each one. For the pain killer Tylenol which is acetaminophen you would type in: how acetaminophen works.

The top hit is about researchers at Vanderbilt University Medical Center who just recently (2002) explained that it works by blocking a brain enzyme whose short name is COX. The entire explanation goes like this:

"Boutaud and colleagues Dr. David M. Aronoff, instructor in Medicine, and Dr. John A. Oates, Thomas F. Frist Professor of Medicine, set out to determine how acetaminophen works. They confirmed what the scientific community assumed was true — acetaminophen works, like aspirin and other non-steroidal anti-inflammatory drugs, by blocking the activity of the cyclooxygenase (COX) enzyme.

But acetaminophen works a little differently to block COX activity. Aspirin, ibuprofen, indomethacin, and other NSAIDs insert into the COX active site — like the wrong key being stuck into a lock. Because they are in the way, the COX enzyme cannot do its normal job of producing prostaglandins.

Acetaminophen doesn’t fit into the lock. Instead, it disrupts the activation of COX by another enzyme activity, a peroxidase, within the same protein. Because this activation is necessary for COX activity, the end effect of acetaminophen and other NSAIDs is the same.

Chemicals called peroxides, though, drive the activation of COX and can overcome the effect of acetaminophen. Because platelets and immune cells generate high levels of peroxides, Boutaud said, acetaminophen doesn’t work well in these cell types. Brain and endothelial cells that participate in fever and pain do not have high levels of peroxides, and acetaminophen is effective in these cells."

You can look up other drugs like ritalin and prozac in the same way. You might have to first determine what the actual chemical is in ritalin or prozac first by googling: ritalin chemical name. And same for prozac.

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