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This is a list of investigational analgesics , or analgesics that are currently under development for clinical use but are not yet approved. Chemical/generic names are listed first, with developmental code names, synonyms, and brand names in parentheses.
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.
Rimonabant (also known as SR141716; trade names Acomplia, Zimulti) is an anorectic antiobesity drug approved in Europe in 2006 but was withdrawn worldwide in 2008 due to serious psychiatric side effects; it was never approved in the United States. Rimonabant is an inverse agonist for the cannabinoid receptor CB1 and was first-in-class for clinical development.
An opioid antagonist, or opioid receptor antagonist, is a receptor antagonist that acts on one or more of the opioid receptors.
Cannabinoid receptor 1 (CB1), is a G protein-coupled cannabinoid receptor that in humans is encoded by the CNR1 gene. The human CB1 receptor is expressed in the peripheral nervous system and central nervous system. It is activated by endocannabinoids, a group of retrograde neurotransmitters that include anandamide and 2-arachidonoylglycerol (2-AG); plant phytocannabinoids, such as docosatetraenoylethanolamide found in wild daga, the compound THC which is an active constituent of the psychoactive drug cannabis; and synthetic analogs of THC. CB1 is antagonized by the phytocannabinoid tetrahydrocannabivarin (THCV).
In pharmacology the term agonist-antagonist or mixed agonist/antagonist is used to refer to a drug which under some conditions behaves as an agonist while under other conditions, behaves as an antagonist.
A cannabinoid receptor antagonist, also known simply as a cannabinoid antagonist or as an anticannabinoid, is a type of cannabinoidergic drug that binds to cannabinoid receptors (CBR) and prevents their activation by endocannabinoids. They include antagonists, inverse agonists, and antibodies of CBRs. The discovery of the endocannabinoid system led to the development of CB1 receptor antagonists. The first CBR inverse agonist, rimonabant, was described in 1994. Rimonabant blocks the CB1 receptor selectively and has been shown to decrease food intake and regulate body-weight gain. The prevalence of obesity worldwide is increasing dramatically and has a great impact on public health. The lack of efficient and well-tolerated drugs to cure obesity has led to an increased interest in research and development of CBR antagonists. Cannabidiol (CBD), a naturally occurring cannabinoid and a non-competitive CB1/CB2 receptor antagonist, as well as Δ9-tetrahydrocannabivarin (THCV), a naturally occurring cannabinoid, modulate the effects of THC via direct blockade of cannabinoid CB1 receptors, thus behaving like first-generation CB1 receptor inverse agonists, such as rimonabant. CBD is a very low-affinity CB1 ligand, that can nevertheless affect CB1 receptor activity in vivo in an indirect manner, while THCV is a high-affinity CB1 receptor ligand and potent antagonist in vitro and yet only occasionally produces effects in vivo resulting from CB1 receptor antagonism. THCV has also high affinity for CB2 receptors and signals as a partial agonist, differing from both CBD and rimonabant.
An opioidergic agent is a chemical which functions to directly modulate the opioid neuropeptide systems in the body or brain. Examples include opioid analgesics such as morphine and opioid antagonists such as naloxone. Opioidergics also comprise allosteric modulators and enzyme affecting agents like enkephalinase inhibitors.
Coronaridine, also known as 18-carbomethoxyibogamine, is an alkaloid found in Tabernanthe iboga and related species, including Tabernaemontana divaricata for which it was named.
SR144528 is a drug that acts as a potent and highly selective CB2 receptor inverse agonist, with a Ki of 0.6 nM at CB2 and 400 nM at the related CB1 receptor. It is used in scientific research for investigating the function of the CB2 receptor, as well as for studying the effects of CB1 receptors in isolation, as few CB1 agonists that do not also show significant activity as CB2 agonists are available. It has also been found to be an inhibitor of sterol O-acyltransferase, an effect that appears to be independent from its action on CB2 receptors.
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.
A receptor modulator, or receptor ligand, is a general term for a substance, endogenous or exogenous, that binds to and regulates the activity of chemical receptors. They are ligands that can act on different parts of receptors and regulate activity in a positive, negative, or neutral direction with varying degrees of efficacy. Categories of these modulators include receptor agonists and receptor antagonists, as well as receptor partial agonists, inverse agonists, orthosteric modulators, and allosteric modulators, Examples of receptor modulators in modern medicine include CFTR modulators, selective androgen receptor modulators (SARMs), and muscarinic ACh receptor modulators.
Peripherally selective drugs have their primary mechanism of action outside of the central nervous system (CNS), usually because they are excluded from the CNS by the blood–brain barrier. By being excluded from the CNS, drugs may act on the rest of the body without producing side-effects related to their effects on the brain or spinal cord. For example, most opioids cause sedation when given at a sufficiently high dose, but peripherally selective opioids can act on the rest of the body without entering the brain and are less likely to cause sedation. These peripherally selective opioids can be used as antidiarrheals, for instance loperamide (Imodium).
RQ-00202730 is a benzimidazole derived drug that acts as a potent and highly selective agonist for the CB2 cannabinoid receptor, with a Ki value of 19nM at CB2 and more than 4000x selectivity over CB1, though it also shows some activity as an antagonist of the unrelated 5-HT2B serotonin receptor. It has analgesic and antiinflammatory effects in animal studies, and was developed for the treatment of irritable bowel syndrome, but was ultimately discontinued from development following disappointing results in Phase II clinical trials.
Phlotoxin is a neurotoxin from the venom of the tarantula Phlogiellus that targets mostly voltage-sensitive sodium channels and mainly Nav1.7. The only non-sodium voltage-sensitive channel that is inhibited by Phlotoxin is Kv3.4. Nav1.4 and Nav1.6 seem to be Phlotoxin-1-sensitive to some extent as well.
{{cite book}}: |work= ignored (help){{cite book}}: |work= ignored (help)Vertex Pharmaceuticals Incorporated (Nasdaq: VRTX) today announced that it has begun a Phase 2 proof-of-concept (POC) study in acute pain following bunionectomy surgery with the selective NaV1.8 inhibitor VX-548 and that it expects to commence a second Phase 2 study in acute pain following abdominoplasty surgery in the coming weeks.
"There is an enormous need for novel non-opioid analgesics with no abuse liability," and Vertex's results are an "important advance," said Dr. Clifford J. Woolf, director of the F.M. Kirby Neurobiology Center and Boston Children's Hospital. It will be important for Vertex to determine whether the drug also works for patients with chronic pain, such as diabetic neuropathy and low back pain, "where the clinical need is highest," he added.