An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist.
Opioids are a class of drugs that derive from, or mimic, natural substances found in the opium poppy plant. Opioids work in the brain to produce a variety of effects, including pain relief. As a class of substances, they act on opioid receptors to produce morphine-like effects.
Mitragyna speciosa is a tropical evergreen tree in the coffee family native to Southeast Asia. It is indigenous to Thailand, Indonesia, Malaysia, Myanmar, and Papua New Guinea, where it has been used in herbal medicine since at least the 19th century. It has also historically been used for chewing, smoking, and tea. Kratom has opiate properties and some stimulant-like effects.
Nalbuphine, sold under the brand names Nubain among others, is an opioid analgesic which is used in the treatment of pain. It is given by injection into a vein, muscle, or fat.
Tianeptine, sold under the brand names Stablon, Tatinol, and Coaxil among others, is an atypical tricyclic antidepressant which is used mainly in the treatment of major depressive disorder, although it may also be used to treat anxiety, asthma, and irritable bowel syndrome.
An analeptic, in medicine, is a central nervous system stimulant. The term "analeptic" typically refers to respiratory analeptics. Analeptics are central nervous system (CNS) stimulants that include a wide variety of medications used to treat depression, attention deficit hyperactivity disorder (ADHD), and respiratory depression. Analeptics can also be used as convulsants, with low doses causing patients to experience heightened awareness, restlessness, and rapid breathing. The primary medical use of these drugs is as an anesthetic recovery tool or to treat emergency respiratory depression. Other drugs of this category are prethcamide, pentylenetetrazole, and nikethamide. Nikethamide is now withdrawn due to risk of convulsions. Analeptics have recently been used to better understand the treatment of a barbiturate overdose. Through the use of agents, researchers were able to treat obtundation and respiratory depression.
BIMU-8 is a drug which acts as a 5-HT4 receptor selective agonist. BIMU-8 was one of the first compounds of this class. The main action of BIMU-8 is to increase the rate of respiration by activating an area of the brain stem known as the pre-Botzinger complex.
The μ-opioid receptors (MOR) are a class of opioid receptors with a high affinity for enkephalins and beta-endorphin, but a low affinity for dynorphins. They are also referred to as μ(mu)-opioid peptide (MOP) receptors. The prototypical μ-opioid receptor agonist is morphine, the primary psychoactive alkaloid in opium and for which the receptor was named, with mu being the first letter of Morpheus, the compound's namesake in the original Greek. It is an inhibitory G-protein coupled receptor that activates the Gi alpha subunit, inhibiting adenylate cyclase activity, lowering cAMP levels.
Trefentanil (A-3665) is an opioid analgesic that is an analogue of fentanyl and was developed in 1992.
CX-546 is an ampakine drug developed by Cortex Pharmaceuticals.
RWJ-394674 is a drug that is used in scientific research. It is a potent, orally active analgesic drug that produces little respiratory depression. RWJ-394674 itself is a potent and selective agonist for δ-opioid receptors, with a Ki of 0.24 nM at δ and 72 nM at μ. However once inside the body, RWJ-394674 is dealkylated to its monodesethyl metabolite RWJ-413216, which is a potent agonist at the μ-opioid receptor and has less affinity for δ. The effect of RWJ-394674 when administered in vivo thus produces potent agonist effects at both μ and δ receptors through the combined actions of the parent drug and its active metabolite, with the δ-agonist effects counteracting the respiratory depression from the μ-opioid effects, and the only prominent side-effect being sedation.
Potassium channel blockers are agents which interfere with conduction through potassium channels.
Amiphenazole (Daptazile) is a respiratory stimulant traditionally used as an antidote for barbiturate or opiate overdose, usually in combination with bemegride, as well as poisoning from other sedative drugs and treatment of respiratory failure from other causes. It was considered particularly useful as it could counteract the sedation and respiratory depression produced by morphine but with less effect on analgesia. It is still rarely used in medicine in some countries, although it has largely been replaced by more effective respiratory stimulants such as doxapram and specific opioid antagonists such as naloxone.
An opioid overdose is toxicity due to excessive consumption of opioids, such as morphine, codeine, heroin, fentanyl, tramadol, and methadone. This preventable pathology can be fatal if it leads to respiratory depression, a lethal condition that can cause hypoxia from slow and shallow breathing. Other symptoms include small pupils, and unconsciousness, however its onset can depend on the method of ingestion, the dosage and individual risk factors. Although there were over 110,000 deaths in 2017 due to opioids, individuals who survived also faced adverse complications, including permanent brain damage.
3-Hydroxymorphinan (3-HM), or morphinan-3-ol, is a psychoactive drug of the morphinan family. It is the racemic counterpart to norlevorphanol.
IBNtxA, or 3-iodobenzoyl naltrexamine, is an atypical opioid analgesic drug derived from naltrexone. In animal studies it produces potent analgesic effects that are blocked by levallorphan and so appear to be μ-opioid mediated, but it fails to produce constipation or respiratory depression, and is neither rewarding or aversive in conditioned place preference protocols. These unusual properties are thought to result from agonist action at a splice variant or heterodimer of the μ-opioid receptor, rather than at the classical full length form targeted by conventional opioid drugs.
Samidorphan is an opioid antagonist that in the form of olanzapine/samidorphan is used in the treatment of schizophrenia and bipolar disorder. Samidorphan reduces the weight gain associated with olanzapine. Samidorphan is taken by mouth.
Trenbolone enanthate, known by the nickname Trenabol, is a synthetic and injected anabolic–androgenic steroid (AAS) and a derivative of nandrolone which was never marketed. It is the C17β enanthate ester and a long-acting prodrug of trenbolone. Trenbolone enanthate was never approved for medical or veterinary use but is used in scientific research and has been sold on the internet black market as a designer steroid for bodybuilders and athletes.
Nalodeine, also known more commonly as N-allylnorcodeine, is an opioid antagonist that was never marketed but is notable as the first opioid antagonist to be discovered. It was first reported in 1915 and was found to block the effects of morphine in animals. This was followed by the clinical introduction of nalorphine (N-allylnormorphine) in 1954, naloxone (N-allyloxymorphone) in 1960, and naltrexone (N-methylcyclopropyloxymorphone) in 1963. Nalmefene (6-desoxy-6-methylene-naltrexone), another structurally related opioid antagonist derivative, was also subsequently introduced, in 1996. In animals, nalodeine both reverses morphine- and heroin-induced respiratory depression and acts as a respiratory stimulant in its own right. Similarly to nalorphine, nalodeine has also been found to act as an agonist of the κ-opioid receptor.
Prescription drug addiction is the chronic, repeated use of a prescription drug in ways other than prescribed for, including using someone else’s prescription. A prescription drug is a pharmaceutical drug that may not be dispensed without a legal medical prescription. Drugs in this category are supervised due to their potential for misuse and substance use disorder. The classes of medications most commonly abused are opioids, central nervous system (CNS) depressants and central nervous stimulants. In particular, prescription opioid is most commonly abused in the form of prescription analgesics.
