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Long-Acting Drug Blocks Opioid Effects, Withdrawal

Pills in blister packs

(PublicDomainPictures, Pixabay)

22 June 2017. Findings from a clinical trial show a formulation of the drug buprenorphine given once a week blocks effects of subsequent opioid exposure and withdrawal symptoms. Results of the trial appear in today’s issue of the journal JAMA Psychiatry and were presented at a meeting of the College on Problems of Drug Dependence now underway in Montreal.

The intermediate-stage clinical trial is testing a drug code-named CAM2038 made by Braeburn Pharmaceuticals in Princeton, New Jersey, and Camurus AB in Lund, Sweden to treat opioid use disorder. Opioids work by reducing the intensity of pain signals to the brain, particularly regions of the brain controlling emotion, which reduces effects of the pain stimulus. Examples of leading opioid prescription pain medications are hydrocodone, oxycodon, morphine, and codeine. Heroin is also considered an opioid.

The U.S. Department of Health and Human Services says the country is in the midst of a “prescription opioid overdose epidemic.” In 2014, according to Centers for Disease Control and Prevention, more than 28,000 people died from opioid overdose, and at least half of those deaths involved a prescription opioid, with even more becoming addicted to prescription and illegal opioids. Heroin-related deaths also increased sharply, more than tripling since 2010, leading to more than 10,500 deaths.

CAM2038 is a formulation of the drug buprenorphine that acts on the same receptors in the brain as heroin and morphine, providing enough satisfaction of those receptors without producing the intense “high” or serious adverse effects of abused drugs. Camurus adapted its injection technology that the company calls FluidCrystal for CAM2038 that combines buprenorphine with a liquid lipid solution to form a gel that that can be injected, yet breaks down slowly in the body to allow for release over extended periods of time.

CAM2038 is designed for delivery via injections under the skin by clinicians, as part of anti-addiction therapy, and can be adjusted for the length of time buprenorphine needs to be released, in this case 1 week. The 47 participants, adults in treatment for moderate or severe opioid use disorder, were randomly assigned to receive injections of CAM2038 at doses of 24 or 38 milligrams on the first day of the trial, then once a week for the next 2 weeks.

During the first 3 days, participants also received injections of varying doses, 0 to 18 milligrams, of the opioid drug hydromorphone, given for chronic moderate to severe pain, then when receiving CAM2038 later on. Participants were asked to report on questionnaires at 4 different points during the test period on their desire to use opioids, liking of drugs, alertness and drowsiness, and experiences of drug highs, as well as good and bad drug effects. Individuals in the trial were also given physical exams that recorded their vital signs, heart functions with electrocardiograms, depression, and adverse effects from CAM2038 or other causes. In addition, participants provided blood samples before and after CAM2038 injections.

The results show participants receiving either dose of CAM2038 blocked the effects of hydromorphone, reported in the self-described desire for opioids and liking of drugs. Individuals in the trial also suppress withdrawal symptoms when empty (0 milligram) doses of hydromorphone were given. The effects were supported by blood tests showing continued concentrations of buprenorphine in the plasma of participants several days after the injections.

Most (81%) of participants experienced some adverse reactions during the trial, usually mild, including constipation, pain at the injection site, skin irritation, headache, and nausea. One individual had to discontinue participation and another developed hepatitis C, in both cases due to causes other than CAM2038.

CAM2038 is currently in a late-stage clinical trial and long-term safety study. Braeburn and Camurus expect the results of these studies will support regulatory approval in the U.S. and Europe.

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