Meptazinol is a unique opioid analgesic. Binding studies suggest a relative selectivity for mu-1 opioid receptor sites. Meptid is indicated for the treatment of moderate to severe pain, including post-operative pain, obstetric pain and the pain of renal colic. The most commonly reported adverse reactions after treatment with meptazinol are nausea, vomiting, dizziness, diarrhoea and increased sweating, constipation, abdominal pain, rash, vertigo, headache, drowsiness, somnolence and dyspepsia.

Dextromoramide is a synthetic strong-acting opioid and full mu-opioid receptor agonist. Dextromoramide is a Schedule I drug illegal to possess. The current indication for Palfium® (dextromoramide) is severe acute or chronic pain requiring opioids, such as post-operative pain, and pain associated with bone fractures, malignancies and acute renal/biliary colic attacks in adults.

Ketobemidone (Cliradon, Ketogan, Ketodur, Cymidon) is a strong opioid analgesic, structurally related to pethidine, which has been in clinical use for more than 50 years. In the Scandinavian countries ketobemidone is only available in combination with a spasmolytic substance N,N-dimethyl-3,3-diphenyl-I-methylallylamine (A29). Ketobemidone has been shown to be a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist. In spite of a relatively low mu-receptor affinity ketobemidone has a higher analgesic potency than morphine by systemic administration. It is probably due to its higher lipophilicity and consequently more easy penetration into the CNS. Ketobemidone is indicated for the treatment of all types of severe pain, such as postoperative, cancer, kidney stones and fractures.

Piritramide is a synthetic opioid that has been used formore than 30 years in parts of Europe as the analgesic of choice for the management of postoperative pain. Piritramide was discovered at Janssen Pharmaceutica in 1960 and is currently manufactured and distributed within continental Europe and some other places by Janssen-Cilag. Piritramide is not available in all countries. It is marketed under the brand name Dipidolor in Germany, Lithuania, Slovenia, Austria. Piritramide is most commonly prescribed i.m. or i.v. for postoperative analgesia. It is used successfully for patient-controlled analgesia in adults 14 and more recently in chil-dren. Piritramide has potency 0.65 to 0.75 times that of morphine. Upon administration, piritramide binds to and activates mu-opioid receptors in the central nervous system (CNS), thereby mimicking the effects of endogenous opioids and producing analgesic relief. The most common side effect of piritramide appears tobe a dose-related incidence of sedation. It is reported in many studies, but rarely accurately quantified. Diaphoresis, urinary retention, flushing, focal myopathy and thrombophlebitis have all been reported. Piritramide is a strong opioid and therefore is regulated much the same as morphine in all known jurisdictions. It was never introduced in the United States and is therefore a Schedule I/Narcotic controlled substance. It is listed under international treaties and other laws such as the German Betabungsmittelgesetz, the Austrian Suchtgiftmittelgesetz, the Opium Laws of various other European countries, Canadian controlled substances act, UK Misuse of Drugs Act of 1971, and equivalents elsewhere.

TILIDINE is a low to medium potency opioid analgesic. It is metabolized to its active metabolites, nortilidine and bisnortilidine. Its analgesic activity is largely exerted through nortilidine which is a potent agonist at Mu opioid receptors.

Hydromorphone (also known as dihydromorphinone and the brand name Dilaudid among others) is a more potent opioid analgesic than morphine and is used for moderate to severe pain. It can be administered by injection, by infusion, by mouth, and rectally. Oral bioavailability is low. The kidney excretes hydromorphone and its metabolites. Some metabolites may have greater analgesic activity than hydromorphone itself but are unlikely to contribute to the pharmacological activity of hydromorphone. With the exception of pruritus, sedation and nausea and vomiting, which may occur less after hydromorphone than after morphine, the side-effects of these drugs are similar. Hydromorphone interacts predominantly with the opioid mu-receptors. These mu-binding sites are discretely distributed in the human brain, with high densities in the posterior amygdala, hypothalamus, thalamus, nucleus caudatus, putamen, and certain cortical areas. It also binds with kappa and delta receptors which are thought to mediate spinal analgesia, miosis and sedation.

Morphine is one of the most important and widely used opioid for the treatment of chronic and acute pain: the very wide interindividual variability in the patients’ response to the drug may have genetic derivations. Sulphate salt of morphine sold under the many brand names, one of them, DURAMORPH, which is indicated for the management of pain severe enough to require use of an opioid analgesic by intravenous administration, and for which alternative treatments are not expected to be adequate. In addition for the epidural or intrathecal management of pain without attendant loss of motor, sensory, or sympathetic function. Morphine is a full opioid agonist and is relatively selective for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of morphine is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia with morphine. The precise mechanism of the analgesic action is unknown. However, specific CNS opioid receptors for endogenous compounds with opioid-like activity have been identified throughout the brain and spinal cord and are thought to play a role in the analgesic effects of this drug. Morphine has a high potential for addiction and abuse. Common side effects include drowsiness, vomiting, and constipation. Caution is advised when used during pregnancy or breast-feeding, as morphine will affect the baby.

Morphine is one of the most important and widely used opioid for the treatment of chronic and acute pain: the very wide interindividual variability in the patients’ response to the drug may have genetic derivations. Sulphate salt of morphine sold under the many brand names, one of them, DURAMORPH, which is indicated for the management of pain severe enough to require use of an opioid analgesic by intravenous administration, and for which alternative treatments are not expected to be adequate. In addition for the epidural or intrathecal management of pain without attendant loss of motor, sensory, or sympathetic function. Morphine is a full opioid agonist and is relatively selective for the mu-opioid receptor, although it can bind to other opioid receptors at higher doses. The principal therapeutic action of morphine is analgesia. Like all full opioid agonists, there is no ceiling effect for analgesia with morphine. The precise mechanism of the analgesic action is unknown. However, specific CNS opioid receptors for endogenous compounds with opioid-like activity have been identified throughout the brain and spinal cord and are thought to play a role in the analgesic effects of this drug. Morphine has a high potential for addiction and abuse. Common side effects include drowsiness, vomiting, and constipation. Caution is advised when used during pregnancy or breast-feeding, as morphine will affect the baby.

Codeine is an opiate used to manage mild to moderate pain severe enough to require an opioid. Codeine is a selective agonist for the mu opioid receptor and has an affinity to delta and kappa-opioid receptors. In some countries, this drug is regulated under various narcotic control laws, because its chronic use can cause physical dependence. In others, it is available without a medical prescription in combination with paracetamol.