Pentazocine

Pentazocine

Clinical data
AHFS/Drugs.com	Monograph (hydrochloride) Monograph (lactate)
Pregnancy category	AU: C
Routes of administration	Oral, IV, IM
ATC code	N02AD01 (WHO)
Legal status
Legal status	AU: S8 (Controlled drug) BR: Class B1 (Psychoactive drugs)[1] CA: Schedule I DE: Anlage III (Special prescription form required) UK: Class B US: Schedule IV UN: Psychotropic Schedule III
Pharmacokinetic data
Bioavailability	~20% orally
Metabolism	Hepatic
Onset of action	15 min[2]
Elimination half-life	2 to 3 hours
Excretion	Renal
Identifiers
IUPAC name (2RS,6RS,11RS)-6,11-dimethyl-3-(3-methylbut-2-en-1-yl)-1,2,3,4,5,6-hexahydro-2,6-methano-3-benzazocin-8-ol or 2-dimethylallyl-5,9-dimethyl-2'-hydroxybenzomorphan
CAS Number	359-83-1 Y
PubChem CID	441278
IUPHAR/BPS	1606
DrugBank	DB00652 Y
ChemSpider	390041 Y
UNII	RP4A60D26L
KEGG	D00498 Y
ChEMBL	ChEMBL560 Y
CompTox Dashboard (EPA)	DTXSID7023433
ECHA InfoCard	100.006.032
Chemical and physical data
Formula	C19H27NO
Molar mass	285.431 g·mol−1
3D model (JSmol)	Interactive image
SMILES Oc1ccc3c(c1)[C@]2([C@H]([C@H](N(CC2)C\C=C(/C)C)C3)C)C
InChI InChI=1S/C19H27NO/c1-13(2)7-9-20-10-8-19(4)14(3)18(20)11-15-5-6-16(21)12-17(15)19/h5-7,12,14,18,21H,8-11H2,1-4H3/t14-,18+,19+/m0/s1 Y Key:VOKSWYLNZZRQPF-GDIGMMSISA-N Y
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Pentazocine,^[3] sold under the brand name Talwin among others, is a painkiller used to treat moderate to severe pain. It is believed to work by activating (agonizing) κ-opioid receptors (KOR) and μ-opioid receptors (MOR). As such it is called an opioid as it delivers its effects on pain by interacting with the opioid receptors. It shares many of the side effects of other opioids like constipation, nausea, itching, drowsiness and respiratory depression, but unlike most other opioids it fairly frequently causes hallucinations, nightmares and delusions. It is also, unlike most other opioids, subject to a ceiling effect, which is when at a certain dose (which differs from person-to-person) no more pain relief, or side effects, is obtained by increasing the dose any further.^[4]

Chemically it is classed as a benzomorphan and it comes in two enantiomers, which are molecules that are exact (non-superimposable) mirror images of one another.

It was patented in 1960 and approved for medical use in 1964.^[5] Usually, in its oral formulations, it is combined with naloxone so as to prevent people from crushing the tablets, dissolving them in a solvent (like water) and injecting them for a high (as orally administered naloxone produces no opioid-negating effects, whereas intravenous or intramuscular administration does).^[4]