Pravadoline (WIN 48,098) is an antinflammatory and

analgesic An analgesic drug, also called simply an analgesic (American English), analgaesic (British English), pain reliever, or painkiller, is any member of the group of drugs used to achieve relief from pain (that is, analgesia or pain management). It ...

drug with an IC₅₀ of 4.9 μM and a ''K''_i of 2511 nM at CB₁, related in structure to

nonsteroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

s (NSAIDs) such as

indometacin Indometacin, also known as indomethacin, is a nonsteroidal anti-inflammatory drug (NSAID) commonly used as a prescription medication to reduce fever, pain, stiffness Stiffness is the extent to which an object resists deformation in response t ...

. It was developed in the 1980s as a new antiinflammatory and

prostaglandin The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derive ...

synthesis inhibitor, acting through inhibition of the enzyme

cyclooxygenase Cyclooxygenase (COX), officially known as prostaglandin-endoperoxide synthase (PTGS), is an enzyme (specifically, a family of isozymes, ) that is responsible for formation of prostanoids, including thromboxane and prostaglandins such as prosta ...

(COX). However, pravadoline was found to exhibit unexpectedly strong analgesic effects, which appeared at doses ten times smaller than the effective anti-inflammatory dose and so could not be explained by its action as a COX inhibitor. These effects were not blocked by opioid

antagonists An antagonist is a character in a story who is presented as the chief foe of the protagonist. Etymology The English word antagonist comes from the Greek ἀνταγωνιστής – ''antagonistēs'', "opponent, competitor, villain, enemy, riv ...

such as

naloxone Naloxone, sold under the brand names Narcan (4 mg) and Kloxxado (8 mg) among others, is a medication used to reverse or reduce the effects of opioids. It is commonly used to counter decreased breathing in opioid overdose. Effects begin within ...

, and it was eventually discovered that pravadoline represented the first compound from a novel class of

cannabinoid Cannabinoids () are several structural classes of compounds found in the cannabis plant primarily and most animal organisms (although insects lack such receptors) or as synthetic compounds. The most notable cannabinoid is the phytocannabinoid tet ...

agonist 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 ago ...

s, the aminoalkylindoles. Pravadoline was never developed for use as an analgesic, partly due to toxicity concerns (although these were later shown to be a result of the salt form that the drug had been prepared in rather than from the pravadoline itself), however the discovery of cannabinoid activity in this structurally novel family of drugs led to the discovery of several new cannabinoid agonists, including the drug

WIN 55,212-2 WIN 55,212-2 is a chemical described as an aminoalkylindole derivative, which produces effects similar to those of cannabinoids such as tetrahydrocannabinol (THC) but has an entirely different chemical structure. WIN 55,212-2 is a potent cannab ...

, which is now widely used in scientific research.

Animal studies

Administration of pravadoline on rats showed: * Prolonged the response latency induced by tail immersion in hot water at a temperature of 55 °C (minimum effective dose 100 mg/kg s.c.) * Prevented

hyperalgesia Hyperalgesia ( or ; 'hyper' from Greek ὑπέρ (huper, “over”), '-algesia' from Greek algos, ἄλγος (pain)) is an abnormally increased sensitivity to pain, which may be caused by damage to nociceptors or peripheral nerves and can ...

in rats with

brewer's yeast Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom. The first yeast originated hundreds of millions of years ago, and at least 1,500 species are currently recognized. They are estimated to constitu ...

injections during ( Randall-Selitto test) (minimum effective dose 1 mg/kg, p.o.) * Prevented the

nociceptive Nociception (also nocioception, from Latin ''nocere'' 'to harm or hurt') is the Somatosensory system, sensory nervous system's process of encoding Noxious stimulus, noxious stimuli. It deals with a series of events and processes required for an org ...

response induced by paw flexion in the

adjuvant In pharmacology, an adjuvant is a drug or other substance, or a combination of substances, that is used to increase the efficacy or potency of certain drugs. Specifically, the term can refer to: * Adjuvant therapy in cancer management * Analgesic ...

-arthritic rat (ED₅₀ 41 mg/kg, p.o.) * Prevented the nociceptive response of

bradykinin Bradykinin (BK) (Greek brady-, slow; -kinin, kīn(eîn) to move) is a peptide that promotes inflammation. It causes arterioles to dilate (enlarge) via the release of prostacyclin, nitric oxide, and endothelium-derived hyperpolarizing factor and ...

-induced head and forepaw flexion (ED₅₀ 78 mg/kg, p.o.) The antinociceptive activity of pravadoline cannot be explained by an opioid mechanism, because pravadoline-induced antinociception was not antagonized by naloxone (1 mg/kg, s.c.) and pravadoline did not bind to the

opioid receptor Opioid receptors are a group of inhibitory G protein-coupled receptors with opioids as ligands. The endogenous opioids are dynorphins, enkephalins, endorphins, endomorphins and nociceptin. The opioid receptors are ~40% identical to somatostatin r ...

s at concentrations up to 10 μM.

References

{{Cannabinoid receptor modulators Aminoalkylindoles Benzoylindoles 4-Morpholinyl compunds WIN compounds Phenol ethers

Animal studies

See also

References