Methylnaltrexone
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Methylnaltrexone
Methylnaltrexone (MNTX, brand name Relistor), used in form of methylnaltrexone bromide ( INN, USAN, BAN), is a medication that acts as a peripherally acting μ-opioid receptor antagonist that acts to reverse some of the side effects of opioid drugs such as constipation without significantly affecting pain relief or precipitating withdrawals. Because MNTX is a quaternary ammonium cation, it cannot cross the blood–brain barrier, and so has antagonist effects throughout the body, counteracting effects such as itching and constipation, but without affecting opioid effects in the brain such as pain relief. However, since a significant fraction (up to 60%) of opioid analgesia can be mediated by opioid receptors on peripheral sensory neurons, particularly in inflammatory conditions such as arthritis, traumatic or surgical pain, MNTX may increase pain under such circumstances. Medical uses Methylnaltrexone is approved for the treatment of opioid-induced constipation in chronic non ...
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Peripherally Acting μ-opioid Receptor Antagonist
Peripherally acting μ-opioid receptor antagonists (PAMORAs) are a class of chemical compounds that are used to reverse adverse effects caused by opioids interacting with receptors outside the central nervous system (CNS), mainly those located in the gastrointestinal tract. PAMORAs are designed to specifically inhibit certain opioid receptors in the gastrointestinal tract and with limited ability to cross the blood–brain barrier. Therefore, PAMORAs do not affect the analgesic effects of opioids within the central nervous system. Discovery and development Opioid drugs are known to cause opioid-induced constipation (OIC) by inhibiting gastric emptying and decreasing peristaltic waves leading to delayed absorption of medications and more water absorption from the feces. That can result in hard and dry stool and constipation for some patients. OIC is one of the most common adverse effects caused by opioids, so the discovery of PAMORAs can prevent the effects that often compromise ...
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Opioid-induced Constipation
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, reversing opioid overdose, and suppressing cough. Extremely potent opioids such as carfentanil are approved only for veterinary use. Opioids are also frequently used non-medically for their euphoric effects or to prevent withdrawal. Opioids can cause death and have been used for executions in the United States. Side effects of opioids may include itchiness, sedation, nausea, respiratory depression, constipation, and euphoria. Long-term use can cause tolerance, meaning that increased doses are required to achieve the same effect, and physical dependence, meaning that abruptly discontinuing the drug leads to unpleasant withdrawal symptoms. The euphoria attracts recreational use, and frequent, escalating recreational use of opioi ...
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Opioid
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use disorder, reversing opioid overdose, and suppressing cough. Extremely potent opioids such as carfentanil are approved only for veterinary use. Opioids are also frequently used non-medically for their euphoric effects or to prevent withdrawal. Opioids can cause death and have been used for executions in the United States. Side effects of opioids may include itchiness, sedation, nausea, respiratory depression, constipation, and euphoria. Long-term use can cause tolerance, meaning that increased doses are required to achieve the same effect, and physical dependence, meaning that abruptly discontinuing the drug leads to unpleasant withdrawal symptoms. The euphoria attracts recreational use, and frequent, escalating recreational use of ...
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6β-Naltrexol
6β-Naltrexol, or 6β-hydroxynaltrexone (developmental code name AIKO-150), is a peripherally-selective opioid receptor antagonist related to naltrexone. It is a major active metabolite of naltrexone formed by hepatic dihydrodiol dehydrogenase enzymes. With naltrexone therapy, 6β-naltrexol is present at approximately 10- to 30-fold higher concentrations than naltrexone at steady state due to extensive first-pass metabolism of naltrexone into 6β-naltrexol. In addition to being an active metabolite of naltrexone, 6β-naltrexol was itself studied for the treatment of opioid-induced constipation. It was found to be effective and well-tolerated, and did not precipitate opioid withdrawal symptoms or interfere with opioid pain relief, but development was not further pursued. 6β-Naltrexol binds to the opioid receptors with affinity (Ki) values of 2.12 nM for the μ-opioid receptor (MOR), 7.24 nM for the κ-opioid receptor (KOR), and 213 nM for the δ-opioid receptor (DO ...
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(+)-Naloxone
(+)-Naloxone (dextro-naloxone) is a drug which is the opposite enantiomer of the opioid antagonist drug (−)- naloxone. Unlike (-)-naloxone, (+)-naloxone has no significant affinity for opioid receptors, but instead has been discovered to act as a selective antagonist of Toll-like receptor 4. This receptor is involved in immune system responses, and activation of TLR4 induces glial activation and release of inflammatory mediators such as TNF-α and Interleukin-1. Relation with opioids Both active and inactive enantiomers of various opioid analgesic drugs including morphine, meperidine, fentanyl, methadone and buprenorphine, as well as some otherwise inactive metabolites like morphine-3-glucuronide, have been found to act as agonists of TLR4, and chronic use of these drugs consequently causes constant low-level release of TNF-α and IL-1β as well as other downstream effects. This is thought to be involved in various adverse properties of opioid analgesic drugs, such as ...
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Naloxegol
Naloxegol (INN; PEGylated naloxol; trade names Movantik and Moventig) is a peripherally acting μ-opioid receptor antagonist developed by AstraZeneca, licensed from Nektar Therapeutics, for the treatment of opioid-induced constipation. It was approved in 2014 in adult patients with chronic, non-cancer pain. Doses of 25 mg were found safe and well tolerated for 52 weeks. When given concomitantly with opioid analgesics, naloxegol reduced constipation-related side effects, while maintaining comparable levels of analgesia. The most common side effects are abdominal pain, diarrhea, nausea, flatulence, vomiting and headache. Patients often describe the above side effects to be similar to an instant withdrawal state brought on quickly rather than the 24 hours it may take to occur naturally. As a pure opioid antagonist Naloxegol has no potential for abuse. Naloxegol was previously a Schedule II drug in the United States because of its chemical similarity to opium alkaloids. It was ...
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Loperamide
Loperamide, sold under the brand name Imodium, among others,Drugs.co Page accessed September 4, 2015 is a medication used to decrease the frequency of diarrhea. It is often used for this purpose in inflammatory bowel disease and short bowel syndrome. It is not recommended for those with blood in the stool, mucus in the stool, or fevers. The medication is taken by mouth. Common side effects include abdominal pain, constipation, sleepiness, vomiting, and a dry mouth. It may increase the risk of toxic megacolon. Loperamide's safety in pregnancy is unclear, but no evidence of harm has been found. It appears to be safe in breastfeeding. It is an opioid with no significant absorption from the gut and does not cross the blood–brain barrier when used at normal doses. It works by slowing the contractions of the intestines. Loperamide was first made in 1969 and used medically in 1976. It is on the World Health Organization's List of Essential Medicines. Loperamide is available as a ge ...
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Loperamide
Loperamide, sold under the brand name Imodium, among others,Drugs.co Page accessed September 4, 2015 is a medication used to decrease the frequency of diarrhea. It is often used for this purpose in inflammatory bowel disease and short bowel syndrome. It is not recommended for those with blood in the stool, mucus in the stool, or fevers. The medication is taken by mouth. Common side effects include abdominal pain, constipation, sleepiness, vomiting, and a dry mouth. It may increase the risk of toxic megacolon. Loperamide's safety in pregnancy is unclear, but no evidence of harm has been found. It appears to be safe in breastfeeding. It is an opioid with no significant absorption from the gut and does not cross the blood–brain barrier when used at normal doses. It works by slowing the contractions of the intestines. Loperamide was first made in 1969 and used medically in 1976. It is on the World Health Organization's List of Essential Medicines. Loperamide is available as a ge ...
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Drug Withdrawal
Drug withdrawal, drug withdrawal syndrome, or substance withdrawal syndrome, is the group of symptoms that occur upon the abrupt discontinuation or decrease in the intake of pharmaceutical or recreational drugs. In order for the symptoms of withdrawal to occur, one must have first developed a form of drug dependence. This may occur as physical dependence, psychological dependence or both. Drug dependence develops from consuming one or more substances over a period of time. Dependence arises in a dose-dependent manner and produces withdrawal symptoms that vary with the type of drug that is consumed. For example, prolonged use of an antidepressant medication is likely to cause a rather different reaction when discontinued compared to discontinuation of an opioid, such as heroin. Withdrawal symptoms from opiates include anxiety, sweating, vomiting, and diarrhea. Alcohol withdrawal symptoms include irritability, fatigue, shaking, sweating, and nausea. Withdrawal from nicotine can ...
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Biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells,Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function.Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.As ...
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United States Adopted Name
A United States Adopted Name (USAN) is a unique nonproprietary name assigned to a medication marketed in the United States. Each name is assigned by the USAN Council, which is co-sponsored by the American Medical Association (AMA), the United States Pharmacopeial Convention (USP), and the American Pharmacists Association (APhA). The USAN Program states that its goal is to select simple, informative, and unique nonproprietary names (also called generic names) for drugs by establishing logical nomenclature classifications based on pharmacological or chemical relationships. In addition to drugs, the USAN Council names agents for gene therapy and cell therapy, List of soft contact lens materials, contact lens polymers, surgical materials, diagnostics, carriers, and substances used as an excipient. The USAN Council works in conjunction with the World Health Organization (WHO) international nonproprietary name (INN) Expert Committee and national nomenclature groups to standardize drug ...
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British Approved Name
A British Approved Name (BAN) is the official, non-proprietary, or generic name given to a pharmaceutical substance, as defined in the British Pharmacopoeia (BP). The BAN is also the official name used in some countries around the world, because starting in 1953, proposed new names were evaluated by a panel of experts from WHO in conjunction with the BP commission to ensure naming consistency worldwide (an effort leading to the International Nonproprietary Name system). There is also a British Approved Name (Modified) (BANM). Combination preparations BANs are unique in that names are assigned for combination preparations as well as single-drug preparations. For example, the BAN Co-amoxiclav is assigned to preparations containing amoxicillin and clavulanic acid. Most other pharmacopoeias simply refer to combination products by both ingredients in the preparation, in this example "amoxicillin with clavulanic acid". The prefix of "co-" is used for many combination drugs, including ...
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