Phenazocine
Encyclopedia
Phenazocine is an opioid
analgesic
drug
, which is related to pentazocine
and has a similar profile of effects.
Effects of phenazocine include analgesia and euphoria
, also may include dysphoria
and hallucinations at high doses, most likely due to action at κ-opioid
and σ receptors
.
Phenazocine appears to be a much stronger analgesic with fewer side effects than pentazocine, probably due to a more favorable μ
/κ binding ratio.
Phenazocine is a much more potent analgesic than pentazocine and other drugs in the benzomorphan series, most probably due to the presence of an N-phenethyl substitution, which is known to boost μ-opioid activity in many classes of opioid analgesics.
Consequently phenazocine is some 4x the potency of morphine
as an analgesic. Also it does not cause spasm of the sphincter of Oddi
, making it more suitable than morphine for the treatment of biliary or pancreatic pain.
opioids (including pentazocine
, dezocine
, and cyclazocine
) developed in the search for non-addictive strong analgesics.
Phenazocine was once widely used, and was mainly supplied as 5mg tablets of the hydrobromide salt for sublingual use (Narphen, Prinadol and other names), but its use was discontinued in the United Kingdom
in 2001.
Phenazocine was briefly used in the United States but fell out of favour for the above-mentioned reasons; it remains a Schedule II substance under the Comprehensive Drug Abuse Control & Prevention Act (aka Controlled Substances Act) of 1970 (CSA) but is not manufactured; other Schedule II narcotics not in use in the United States include bezitramide
and metopon
.
Opioid
An opioid is a psychoactive chemical that works by binding to opioid receptors, which are found principally in the central and peripheral nervous system and the gastrointestinal tract...
analgesic
Analgesic
An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....
drug
Drug
A drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
, which is related to pentazocine
Pentazocine
Pentazocine is a synthetically prepared prototypical mixed agonist-antagonist narcotic drug of the benzomorphan class of opioids used to treat moderate to moderately severe pain...
and has a similar profile of effects.
Effects of phenazocine include analgesia and euphoria
Euphoria
Euphoria is an emotional and mental state defined as a sense of great elation and well being.Euphoria may also refer to:* Euphoria , a genus of scarab beetles* Euphoria, a genus name previously used for the longan and other trees...
, also may include dysphoria
Dysphoria
Dysphoria is medically recognized as a mental and emotional condition in which a person experiences intense feelings of depression, discontent and indifference to the world around them.Mood disorders can induce dysphoria, often with a heightened risk of suicide, especially in...
and hallucinations at high doses, most likely due to action at κ-opioid
Kappa Opioid receptor
The κ-opioid receptor is a protein that in humans is encoded by the OPRK1 gene. The κ-opioid receptor is one of five related receptors that bind opium-like compounds in the brain and are responsible for mediating the effects of these compounds...
and σ receptors
Sigma receptor
The sigma receptors σ1 and σ2 bind to ligands such as 4-PPBP, SA 4503, ditolylguanidine, dimethyltryptamine and siramesine.- Classification :...
.
Phenazocine appears to be a much stronger analgesic with fewer side effects than pentazocine, probably due to a more favorable μ
Mu Opioid receptor
The μ-opioid receptors are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ refers to morphine...
/κ binding ratio.
Phenazocine is a much more potent analgesic than pentazocine and other drugs in the benzomorphan series, most probably due to the presence of an N-phenethyl substitution, which is known to boost μ-opioid activity in many classes of opioid analgesics.
Consequently phenazocine is some 4x the potency of morphine
Morphine
Morphine is a potent opiate analgesic medication and is considered to be the prototypical opioid. It was first isolated in 1804 by Friedrich Sertürner, first distributed by same in 1817, and first commercially sold by Merck in 1827, which at the time was a single small chemists' shop. It was more...
as an analgesic. Also it does not cause spasm of the sphincter of Oddi
Sphincter of Oddi
The sphincter of ampulla or sphincter of Oddi is a muscular valve that controls the flow of digestive juices through the ampulla of Vater into the second part of the duodenum. It is named after Ruggero Oddi...
, making it more suitable than morphine for the treatment of biliary or pancreatic pain.
History
Phenazocine was invented in the 1950s. It was one of a number of benzomorphanBenzomorphan
Benzomorphan is a chemical compound.It is the base for a series of drugs which variably act on the opioid and sigma receptors, including, but not limited to, the following compounds:...
opioids (including pentazocine
Pentazocine
Pentazocine is a synthetically prepared prototypical mixed agonist-antagonist narcotic drug of the benzomorphan class of opioids used to treat moderate to moderately severe pain...
, dezocine
Dezocine
Dezocine was developed by American Home Products and is an opioid analgesic related to pentazocine, with a similar profile of effects that include analgesic action and euphoria at low doses, but produces dysphoria and hallucinations at high doses, most likely due to action at κ-opioid...
, and cyclazocine
Cyclazocine
Cyclazocine is a mixed opioid agonist/antagonist related to dezocine, pentazocine and phenazocine. This family of opioid drugs is called the benzomorphans or benzazocines.- Use :...
) developed in the search for non-addictive strong analgesics.
Phenazocine was once widely used, and was mainly supplied as 5mg tablets of the hydrobromide salt for sublingual use (Narphen, Prinadol and other names), but its use was discontinued in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
in 2001.
Phenazocine was briefly used in the United States but fell out of favour for the above-mentioned reasons; it remains a Schedule II substance under the Comprehensive Drug Abuse Control & Prevention Act (aka Controlled Substances Act) of 1970 (CSA) but is not manufactured; other Schedule II narcotics not in use in the United States include bezitramide
Bezitramide
Bezitramide is a narcotic analgesic. Bezitramide itself is a prodrug which is readily hydrolyzed in the gastrointestinal tract to its main metabolite, despropionyl-bezitramide. Bezitramide was discovered at Janssen Pharmaceutica in 1961...
and metopon
Metopon
Metopon is an opiate analogue that is a methylated derivative of hydromorphone which was invented in 1948 as an analgesic....
.