Pentazocine

Pentazocine
Clinical data
AHFS/Drugs.com	Monograph (hydrochloride); Monograph (lactate)
Pregnancy; category	AU: C;
Routes of; administration	By mouth, intramuscular, intravenous
Drug class	Opioid
ATC code	N02AD01 (WHO) ;
Legal status
Legal status	AU: S8 (Controlled drug); BR: Class B1 (Psychoactive drugs); 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
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 ;
PubChem CID	441278;
IUPHAR/BPS	1606;
DrugBank	DB00652 ;
ChemSpider	390041 ;
UNII	RP4A60D26L;
KEGG	D00498 ;
ChEMBL	ChEMBL560 ;
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 ; Key:VOKSWYLNZZRQPF-GDIGMMSISA-N ;
	(verify)

Pentazocine, sold under the brand name Talwin among others, is an analgesic medication 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 no more pain relief is obtained by increasing the dose any further.

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. 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 as it has no oral bioavailability, whereas intravenous or intramuscular administration does).