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You can get a $100 60-day  credit on a new Linode account at linode.com/scishow. In the early 1990s, researchers in the UK began clinical trials using  a drug called sildenafil to treat chest pain.

It didn’t turn out to be particularly  promising for that purpose, but subjects reported an unexpected side effect that caught the researchers’ attention. They began focusing on that instead, and in 1998, the FDA approved sildenafil for sale under the brand name Viagra. This isn’t the only time that a drug has been repurposed because  of useful side effects.

In fact, it might be about to happen again, but this time, we may be honing in on a treatment for addiction. [intro song] Our star today is a medication called semaglutide, which you may be familiar with by its brand names, Ozempic and Wegovy. The two brands are the same active compound, but at different doses, and they also have different uses. Ozempic was originally approved by the FDA in 2017 to treat type 2 diabetes, and Wegovy was approved in 2021 for what doctors refer to as  “chronic weight management”.

After semaglutide was approved  for weight management, the drug skyrocketed in popularity. Which turned out to be kind of a problem, because people who’d been taking it for years to treat their diabetes were all of a sudden having trouble getting their hands on it, due to supply shortages. But as more people began taking semaglutide, some of them also began reporting  that once they started taking Ozempic, they were no longer all that  interested in drinking alcohol.

Even those who’d self-reported  addictive tendencies or unhealthy fixations on alcohol  suddenly felt cravings stop, just like that. And that isn’t quite as far  out of left field as it sounds, once you understand exactly how semaglutide works. Semaglutide mimics a naturally occurring hormone called glucagon-like peptide 1, or GLP-1, that’s released primarily in the gut after eating, and raises insulin levels to  stabilize your blood sugar.

Semaglutide is only one of many medications that mimic GLP-1, and the first of these drugs was approved in 2005. They work by binding with receptors in the pancreas to stimulate insulin production. Plus they can also slow down how  quickly your stomach empties, which leaves you feeling fuller for longer.

The entire class of drugs is actually named after those receptors the hormone binds with, not the hormone itself, so they’re called GLP-1 receptor agonists. It’s the insulin boosting effect  that GLP-1 receptor agonists capitalize on to treat diabetes. The increased feeling of fullness means less appetite and fewer  cravings for high-fat foods, which can result in weight loss.

Even though GLP is mostly released in the gut, there are GLP-1 receptors throughout the body including areas of the brain typically associated with reward and addiction. And so scientists have  studied various GLP-1 agonists to see how they might affect addictive behaviors. In mice, rats, and even non-human primates, giving an animal a GLP-1 agonist reduces how much alcohol they drink and decreases the rewarding  effects of drinking alcohol.

And in other animal studies, those GLP-1 agonists have also been shown to decrease cocaine consumption,  cocaine-related hyperactivity, and dopamine release in  reward-related areas of the brain. Rodent studies also show decreased  rewarding effects of nicotine, as well as decreased  nicotine-induced hyperactivity. by blunting the effects and  making them less rewarding. That’s different from the current treatments that make you feel sick when you take drugs or drink alcohol so you stop doing it.

These GLP-1 agonists appear  to actually be changing how much of a dopamine hit comes  from the addictive substance, although scientists don’t yet know exactly how they interact with that dopamine. But there still aren’t many human studies on GLP-1 and addiction that have been completed yet, and almost none involve semaglutide specifically. One of those few human studies found  that one GLP-1 receptor agonist reduced alcohol use in patients who were obese, but not in patients who weren’t.

As of June 2023, there have only been a  handful of studies published that specifically look at  semaglutide and addiction. Those studied rodents, and they suggested semaglutide  decreases alcohol intake and the activity of  reward-mechanisms in the brain, so they’re a really promising start. But the jury’s still out on  whether GLP-1 receptor agonists in general will work to reduce addictive behaviors in clinical trials on humans.

Semaglutide definitely seems  to have an effect in people, but right now we only have anecdotal  reports of reduced interest in drinking and other addictive behaviors. It’s possible that this only happens  in a small minority of people, it just feels like a lot right now because so many people have recently started taking it and we’re paying attention to those reports. Plus, a lot of the rodent testing  has focused on short-term effects after getting a GLP-1 receptor agonist injection.

That doesn’t really tell  us if a drug will continue to be effective for long-term treatment. And since substance use disorders  are long-term, chronic issues, that’s an important question to answer, too.   Really, just about any question about  addiction treatment is an important one. Addiction is incredibly difficult to treat.

There are only a few medications on the market to treat some substance use disorders,  and they don’t work for everyone. And while a few drugs show promise, there are currently no approved medications for cocaine or methamphetamine addiction, so finding and approving new drugs  could truly be a gamechanger. But we can’t do that without human studies looking at semaglutide and substance use, which are currently underway.

And if it does work, an added bonus is that drugs already approved by the FDA for another condition are approved more quickly than brand new drugs. New drugs take years of animal  and human safety testing to get the green light. With an already approved drug, the mechanism of how it works is already known, as are the side effects, which makes the whole process move faster.

It even happened with Viagra in 2005, when the active ingredient was finally approved for pulmonary hypertension, on a shorter timeline than  it took to get the first one. Hopefully, the clinical trials  of semaglutide are successful, and these anecdotal reports will be the first step toward more  effective treatment of addiction. It could save a lot of lives and a lot of pain, all because a new drug happened  to have very useful side effects.

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