Opioids are chemicals that bind to opioid receptors which are located all throughout the brain & body. Opioids are often recognized by their use in painkilling medication such as morphine or oxycodone as well as in illegal drugs like opium or heroin. The main problem with opioids is that they are addictive & can lead people to become dependent on them. However research is being done on low-dose opioid drugs that may be of use to those with IBS.
Loperamide is a common anti-diarrheal medication which acts on the mu opioid receptors in the large intestine. It reduces contractions of the smooth wall muscle structure inside the large intestine, reducing diarrhea, cramping & urgency.
Naltrexone is a drug that has been studied for it’s uses on a wide array of problems such as alcohol dependance, sexual dysfunction, Crohn’s Disease & even IBS. While one of the studies that investigated it’s usefulness for IBS showed some promising results for the first two months, the positive results were not sustained into the third month of the study. Advocates of Low Dose Naltrexone(LDN) stated that the dosage was too small, at only 0.5mg. They suggested that a dosage of around 1.75mg should be investigated. There haven’t been any studies involving IBS & 1.75mg of Naltrexone.
Mu Delta is a drug being developed by Furiex. It is an opioid agonist that targets 2 of the 4 major opioid receptor subtypes, “Mu” & “Delta”, both of which are prominent in the digestive tract & nervous system. The design goal of Mu Delta is for most of the drug to remain within the gastrointestinal nervous system, helping to regulate it. It is not currently on the market, but is undergoing study trials.
Asimadoline is a drug being developed by Tioga Pharmaceuticals. Asimadoline is an opioid agonist that targets the kappa opioid receptors. The kappa opioid receptors are mainly located in the brain, spinal cord & peripheral nervous system. Asimadoline is designed not to cross the blood brain barrier & into the brain, which should reduce or eliminate psychoactive effects as well as reduce dependency problems. By targeting the peripheral nervous system, Asimadoline has been shown to help with pain & urgency associated with diarrhea predominant IBS. It is currently in Phase III trials with the FDA.