Nalorphine () (brand names Lethidrone, Nalline), also known as ''N''-allylnormorphine, is a mixed
opioid
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid us ...
agonist–antagonist
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 (a substance that fully activates the receptor that it binds to) while under other conditions, beh ...
with
opioid antagonist
An opioid antagonist, or opioid receptor antagonist, is a receptor antagonist that acts on one or more of the opioid receptors.
Naloxone and naltrexone are commonly used opioid antagonist drugs which are competitive antagonists that bind to the o ...
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 ...
properties.
It was introduced in 1954
and was used as an
antidote
An antidote is a substance that can counteract a form of poisoning. The term ultimately derives from the Greek term φάρμακον ἀντίδοτον ''(pharmakon) antidoton'', "(medicine) given as a remedy". Antidotes for anticoagulants are s ...
to reverse
opioid overdose
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 ca ...
and in a challenge test to determine
opioid dependence
Opioid use disorder (OUD) is a substance use disorder characterized by cravings for opioids, continued use despite physical and/or psychological deterioration, increased tolerance with use, and withdrawal symptoms after discontinuing opioids. Op ...
.
Nalorphine was the second opioid antagonist to be introduced, preceded by
nalodeine
Nalodeine, also known more commonly as N-allylnorcodeine, is an opioid antagonist (specifically, an antagonist of the μ-opioid receptor) that was never marketed but is notable as the first opioid antagonist to be discovered. It was first reporte ...
(''N''-allylnorcodeine) in 1915 and followed by
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 ...
in 1960 and
naltrexone
Naltrexone, sold under the brand name Revia among others, is a medication primarily used to manage alcohol or opioid use disorder by reducing cravings and feelings of euphoria associated with substance use disorder. It has also been found t ...
in 1963.
Due to potent activation of the
κ-opioid receptor
The κ-opioid receptor or kappa opioid receptor, abbreviated KOR or KOP, is a G protein-coupled receptor that in humans is encoded by the ''OPRK1'' gene. The KOR is coupled to the G protein Gi/G0 and is one of four related receptors that bind op ...
, nalorphine produces
side effect
In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequence ...
s such as
dysphoria
Dysphoria (; ) is a profound state of unease or dissatisfaction. It is the semantic opposite of euphoria. In a psychiatric context, dysphoria may accompany depression, anxiety, or agitation.
In psychiatry
Intense states of distress and unea ...
,
anxiety
Anxiety is an emotion which is characterized by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different than fear in that the former is defined as the anticipation of a future threat wh ...
,
confusion
In medicine, confusion is the quality or state of being bewildered or unclear. The term "acute mental confusion" , and
hallucination
A hallucination is a perception in the absence of an external stimulus that has the qualities of a real perception. Hallucinations are vivid, substantial, and are perceived to be located in external objective space. Hallucination is a combinatio ...
s, and for this reason, is no longer used medically.
Pharmacology
Pharmacodynamics
Nalorphine acts at two
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 — the
μ-opioid receptor
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 ...
(MOR) where it has
antagonist
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 ...
ic effects, and at the
κ-opioid receptor
The κ-opioid receptor or kappa opioid receptor, abbreviated KOR or KOP, is a G protein-coupled receptor that in humans is encoded by the ''OPRK1'' gene. The KOR is coupled to the G protein Gi/G0 and is one of four related receptors that bind op ...
(KOR) (K
i = 1.6 nM;
EC50 = 483 nM;
Emax = 95%) where it exerts high-
efficacy
Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as ''effectiveness'', and it has often been used synonymously, although in pharmacology a pragmatic clinical trial#Efficacy versu ...
partial agonist
In pharmacology, partial agonists are drugs that bind to and activate a given receptor, but have only partial efficacy at the receptor relative to a full agonist. They may also be considered ligands which display both agonistic and antagonistic e ...
/near-
full 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 ...
characteristics.
Chemistry
Analogues
Nalorphine has a number of
analogues including
niconalorphine
Nalorphine dinicotinate (trade name Nimelan), also known as ''N''-allylnormorphine dinicotinate, dinicotinoylnalorphine, or niconalorphine, is a semisynthetic, mixed opioid agonist-antagonist which is described as a narcotic antagonist but may pr ...
(the
nicomorphine
Nicomorphine (Vilan, Subellan, Gevilan, MorZet) is the 3,6-dinicotinate ester of morphine. It is a strong opioid agonist analgesic two to three times as potent as morphine with a side effect profile similar to that of dihydromorphine, morphine, a ...
analogue),
diacetylnalorphine
Diacetylnalorphine (BAN), also known as ''O''3,''O''6-diacetyl-''N''-allyl-normorphine, is an opioid drug described as an analgesic and antidote which was never marketed. It is the 3,6-diacetyl ester of nalorphine, and therefore the heroin analog ...
(
heroin
Heroin, also known as diacetylmorphine and diamorphine among other names, is a potent opioid mainly used as a recreational drug for its euphoric effects. Medical grade diamorphine is used as a pure hydrochloride salt. Various white and brow ...
analogue),
dihydronalorphine (dihydromorphine), and a number of others as well as a number of
codeine
Codeine is an opiate and prodrug of morphine mainly used to treat pain, coughing, and diarrhea. It is also commonly used as a recreational drug. It is found naturally in the sap of the opium poppy, ''Papaver somniferum''. It is typically use ...
-based analogues.
Synthesis
![Nalorphine synthesis](https://upload.wikimedia.org/wikipedia/commons/a/a2/Nalorphine_synthesis.png)
More recently, it has become much more commonplace to use
ethyl chloroformate
Ethyl chloroformate is the ethyl ester of chloroformic acid. It is a reagent used in organic synthesis for the introduction of the ethyl carbamate protecting group and for the formation of carboxylic anhydrides.
Preparation
Ethyl chloroforma ...
instead of
cyanogen bromide
Cyanogen bromide is the inorganic compound with the formula (CN)Br or BrCN. It is a colorless solid that is widely used to modify biopolymers, fragment proteins and peptides (cuts the C-terminus of methionine), and synthesize other compounds. ...
for the
Von Braun degradation demethylation step. See for example the
list of phenyltropanes or the synthesis of
paroxetine
Paroxetine, sold under the brand names Paxil and Seroxat among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. It is used to treat major depressive disorder, obsessive-compulsive disorder, panic disorder ...
for further examples of this.
See also
*
Diacetylnalorphine
Diacetylnalorphine (BAN), also known as ''O''3,''O''6-diacetyl-''N''-allyl-normorphine, is an opioid drug described as an analgesic and antidote which was never marketed. It is the 3,6-diacetyl ester of nalorphine, and therefore the heroin analog ...
*
Levallorphan
Levallorphan ( INN, BAN) (brand names Lorfan, Naloxifan, Naloxiphan), also known as levallorphan tartrate (USAN), is an opioid modulator of the morphinan family used as an opioid analgesic and opioid antagonist/antidote. It acts as an antagonist ...
*
Nalbuphine
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.
Side effects of nalbuphine include sedation, sweatiness, clammin ...
*
Nalorphine dinicotinate
Nalorphine dinicotinate (trade name Nimelan), also known as ''N''-allylnormorphine dinicotinate, dinicotinoylnalorphine, or niconalorphine, is a semisynthetic, mixed opioid agonist- antagonist which is described as a narcotic antagonist but may ...
References
Abandoned drugs
Allyl compounds
Antidotes
Cyclohexenes
Dissociative drugs
4,5-Epoxymorphinans
Kappa-opioid receptor agonists
Mu-opioid receptor antagonists
Phenols
Secondary alcohols
Semisynthetic opioids
{{Analgesic-stub