Pain Experts Say New Opioid Has ‘Enormous’ Potential

Pain Experts Say New Opioid Has ‘Enormous’ Potential

An experimental opioid drug designed to alleviate acute pain without the risk of abuse or addiction has “enormous” potential to treat some types of chronic pain, according to pain management experts.

“There’s a great opportunity for drugs like that. We really need to find something that doesn’t have rewarding properties that doesn’t lead to addiction,” said Lynn Webster, MD, past president of the American Academy of Pain Medicine, who was the lead investigator in initial studies of the drug.

Image courtesy of Cara Therapeutics.

Image courtesy of Cara Therapeutics.

The injectable analgesic – which for now has clunky name CR845 – was developed by Cara Therapeutics (NASDAQ: CARA), a Connecticut biopharmaceutical company. The company recently released the results of human abuse liability studies of CR845 on recreational drug users — who gave it very low scores for drug “liking” and making them feel “high.”

“The results are especially encouraging because CR845 was administered by rapid intravenous injection, which provides the fastest delivery of the highest level of drug into the bloodstream, a critical determinant of abuse liability,” said Derek Chalmers, PhD, President and CEO of Cara Therapeutics.

Unlike other narcotics, CR845 doesn’t act on opioid receptors in the brain and central nervous system – which can cause side effects such as respiratory depression, nausea, vomiting, and the euphoria that can lead to abuse and addiction. Instead, CR845 acts on receptors in nerve endings – in what is known as the peripheral nervous system.

“It doesn’t enter the brain very well, if at all. It has minimal brain entry. So it works peripherally as an analgesic. And as a result it didn’t demonstrate any rewarding properties. That means it wasn’t liked, it doesn’t have any liking effect, and it does not have any significant abuse potential,” Webster told National Pain Report.

Cara Therapeutics hopes to begin Phase III clinical studies on CR845 in early 2015. If those efficacy studies are successful and it gets FDA approval – which could take years – the drug is most likely to be used as an injectable analgesic to treat acute pain caused by injuries or surgery.

But someday it could also become available in pill form to treat chronic pain.

“I think it can be. I don’t see any reason why eventually it couldn’t become an oral medication,” says Webster. “Initially this is going to be hospital based, for emergency rooms or acute care. But if it is effective as an analgesic, because of the low abuse potential this would be an enormous opportunity to (use) a safer, more effective analgesic that would avoid some of the rewarding properties of the current opioids. I would hope they would develop it.”

But because CR845 primarily works on the peripheral nervous system, Webster and other experts say it most likely won’t be effective treating spinal pain or other types of chronic pain that originate in the central nervous system.

“You may see it being useful for something like arthritis, where there is constant pressure and inflammation of joints that create the pain. But it’s not likely to be effective for other types of central nervous system pain, like fibromyalgia. It’s probably not going to work for that,” said Bob Twillman, PhD, Deputy Executive Director of Policy and Advocacy for the American Academy of Pain Management.

“I think there’s a huge need for it. I think the potential is fantastic. What this is most likely to replace is a lot of the short acting medications that we use for acute pain. It may have some applications for chronic pain, but for the most part this is going to be an acute pain medication. “

But even if CR845 is only approved for acute pain, Twillman says it could be a major step forward in reducing the risk of opioid addiction.

“All of the people who first get exposed to opioids in the context of some sort of injury or having their wisdom teeth pulled, surgery or whatever; those folks get this medication instead and never have that first exposure to an opioid that could eventually lead them to a substance abuse problem.”

Authored by: Pat Anson, Editor

There are 7 comments for this article
  1. Barbara Hamm at 6:52 am

    I have debilitating pain that has been chronic for 20yrs now, after taking opiates our bodies become immune to their effectiveness therefore becoming a vicious cycle of higher doses which is dangerous to our bodies. I live in a medical marijuana state and can tell you from experience that Cannabis in all forms (smoking, creams, tinctures, oils, edibles ect) have been the most effective pain reliever I have tried without harmful side effects. We have pharmaceutical marijuana-Marinol, which is synthetic and not the same as the natural whole plant of Cannabis. Cannabis in oil form CBD is a Non lethal treatment for cancer, epilepsy and many others. It’s antibacterial-antifungal (Cancer) antianxiety-antiviral properties in CBD oil is Amazing! A plant that was put here, used for ththousands of years as one of the best healing herbs available. Pharmaceutical Companies along with Government started the Reefer madness and made this plant illegal as well as putting it in the class of drugs with Cocaine-Heroin ect. They did this because they knew of its healing abilities and would loose trillions in pharmaceuticals. I personally prefer Cannabis for chronic pain, seizures, sleep, appetite as opposed to man made synthetic drugs full of toxic fillers and a high likelyhood of death from these RX`s. Cannabis has 0 death rate and promotes healing….

  2. Mark Bouquet at 9:43 am

    I live in horiffic pain 24/7 and no longer know what to do. I have a pain pump but even that doesn’t work. What am I supposed to do? I can’t take it anymore. I prefer death to living like this. If I was sure I wouldn’t go to hell, I would have committed suicide 20 years ago. I cannot believe in this day and age we still haven’t figured this out. I don’t know how long I will make it but I hope this is realized soon because if it isn’t, suicide is a risk I will just have to take.

  3. Stephen S. Rodrigues, MD at 2:41 pm

    Just as a few reminders:

    We already have great pain meds or ways to relieve acute pain, but the more pain meds the more the brain is affected. That is ok in the hospital or for acute problems.

    Finding the perfect pain medication for “long-term pain” will be a challenge. One that stops pain without altering your wellbeing, sense of awareness or productivity, will not accumulate to toxic levels affecting the kidneys or liver and will not with not induce tolerance or withdrawals.

    We truly do not know where pain is generated, it’s triggers, how it travels and where it is perceived. Pain is an electrical impulse perceived as an alert; I use and like the simpler terms, danger pain or need pain

    Danger pain means go to the hospital get help or you will die. These hit you hard and have set characteristics base on centuries of evidence. Appendix, gallstones, aneurysm, acute infections MI etc.

    Need pain is a “request” to do something to assist your body and its functioning. Again simple concepts, ie a thirst means water; #1 or #2 pain means you gotta go; hunger means food; sleepy means sleep; muscle strain means heat, rest and massage; ankle sprain means rest and wait and broken bone means brace and wait.

    The longer you put off a “need pain” the more intense the signal. Your body will grace you for a period and then it will shut you down, drive you crazy or you will be very embarrassed.

    IMO, muscles will collect stress and give you nudges like a ache, tightness, spasm, soreness. The request is always to heat, stretch, massage and rest + repeat. Ignore the warning signs and your body will shut you down. The pain signals will be so overwhelming you will vomit. This does not mean “danger pain,” it is just your body yelling at you for help. Like thirst a need pain may not be able to be completely relieved at that moment and it may take some time. Muscles will collect “microscars” until they reach a critical level then they will wreak havoc on your soul. The longer you wait before therapy, the longer it may take for the muscles to fully recover. I have patients who needed therapy for years to whittle down the “microscars” until the “need pain” signs were no more.
    (Microscars is used instead of myofascial trigger points or tender points)

  4. Veronica Clark at 1:19 pm

    I will never, ever, use ANY drug that has to be injected like I am a junkie!! Even tho I am in pain 24/7 due to several ‘factual’ medical problems, and fibro myalgia, I would rather suffer than have needles in my house. If they can’t figure out a pill form, then in my opinion, they haven’t done anything, nor have they tried too hard for those of us that do suffer every single day. You may call that a ‘breakthrough’, but I call it bull.

  5. Kurt W.G. Matthies at 11:25 am

    I have mixed feelings about this medication.

    First, for the acute pain generated from peripheral nervous system trauma, sounds like CR845 is a good idea, but only if it is effective. Unfortunately today, we’re more interested in anti-abuse forumlations than effective pain medication.

    However, it’s long been held that chronic pain syndrome is a disease of the central nervous system. Since CR845 has no effect on the opioid receptors of the spine and brain, it will likely be ineffective against chronic pain.

    I hope that people affected by acute pain will soon have an effective choice of medication, other than a strong NSAID like Toradol. But people in chronic pain conditions remain lacking a politically acceptable answer to their suffering.

  6. Stephen S. Rodrigues, MD at 9:26 am

    Mr Anson, your researching and reports are invaluable, thanks.

    “But someday it could also become available in pill form to treat chronic pain.”

    This is great for the distant future of medicine! What about now?

    Everyone is searching for future “miracle” cure or thingy. Like most snake oil salesmen, they have to get you to believe that there is not one already available. Or. They have to get you to believe that theirs is better.

    Do you really think that the people who got us in the situation will get us out?

    For many in the world outside of Conventional Medicine, the miracle was never forgotten, hidden or lost. For those of us who understand that the many old school treatments for long-term pain and dysfunction are still working just fine. They are a gift from Mother Nature.

    I don’t know how else to say it, “don’t get stuck without options and alternatives.”

  7. mark maginn at 6:18 am

    This looks like a real possibility for surgical and acute pain. I wonder if it can be developed for long term chronic pain. My only negative reaction is that the premise of this medicine suggest that because it is difficult of this med to cross over into the brain thus lessening and “liking” of it by the patient it has little possibility for abuse by a person with pain. This plays into the wrongheaded notion that pain patients become addicted to their opioid medicines and thus become not only a medical but also a society problem. Yes, there are a very small # of pain patients who become addicted and then require other services, but on the whole, this doesn’t happen.