Pethidine

Pethidine

Clinical data
Trade names	Demerol
Pregnancy category	AU: C US: C (Risk not ruled out)
Dependence liability	High
Routes of administration	oral, intravenous, intramuscular, subcutaneous
ATC code	N02AB02 (WHO)
Legal status
Legal status	AU: S8 (Controlled) CA: Schedule I DE: Anlage III (Prescription only) NZ: Class B3 UK: Class A US: Schedule II UN: Narcotic Schedule I
Pharmacokinetic data
Bioavailability	50–60% (Oral), 80-90% (Oral, in cases of hepatic impairment)
Protein binding	65-75%
Metabolism	Liver
Biological half-life	2.5-4 hours, 7-11 hours (liver disease)
Excretion	Renal
Identifiers
IUPAC name Ethyl 1-methyl-4-phenylpiperidine-4-carboxylate
Synonyms	meperidine
CAS Number	57-42-1 Y
PubChem (CID)	4058
IUPHAR/BPS	7221
DrugBank	DB00454 Y
ChemSpider	3918 Y
UNII	9E338QE28F Y
KEGG	D08343 Y
ChEMBL	CHEMBL607 Y
ECHA InfoCard	100.000.299
Chemical and physical data
Formula	C15H21NO2
Molar mass	247.33g/mol
3D model (Jmol)	Interactive image
SMILES O=C(C1(CCN(CC1)C)C2=CC=CC=C2)OCC
InChI InChI=1S/C15H21NO2/c1-3-18-14(17)15(9-11-16(2)12-10-15)13-7-5-4-6-8-13/h4-8H,3,9-12H2,1-2H3 Y= Key:XADCESSVHJOZHK-UHFFFAOYSA-N Y=

Pethidine, also known as meperidine and Demerol, is a synthetic opioid pain medication of the phenylpiperidine class. Synthesized in 1939 as a potential anticholinergic agent by the German chemist Otto Eisleb, its analgesic properties were first recognized by Otto Schaumann while working for IG Farben, Germany. Pethidine was the first wholly synthetic opioid developed and is the prototype of a large family of analgesics including the pethidine 4-phenylpiperidines (pethidine, piminodine, anileridine and others), the prodines (alphaprodine, MPPP, etc.), bemidones (ketobemidone, etc.) and others more distant, including diphenoxylate and analogues.

Pethidine is indicated for the treatment of moderate to severe pain, and is delivered as a hydrochloride salt in tablets, as a syrup, or by intramuscular, subcutaneous, or intravenous injection. For much of the 20th century, pethidine was the opioid of choice for many physicians; in 1975, 60% of doctors prescribed it for acute pain and 22% for chronic severe pain.

Compared with morphine, pethidine was thought to be safer, carry a lower risk of addiction, and to be superior in treating the pain associated with biliary spasm or renal colic due to its putative anticholinergic effects. These were later discovered to be all myths, as it carries an equal risk of addiction, possesses no advantageous effects on biliary spasm or renal colic compared to other opioids, and due to its toxic metabolite norpethidine is more toxic than other opioids - especially during long-term use. The norpethidine metabolite was found to have serotonergic effects, so pethidine could, unlike most opioids, contribute to serotonin syndrome.

Pethidine can be produced in a two-step synthesis. The first step is starting from benzyl cyanide and bis (chloroethyl) methylamine in the presence of sodium amide cyclization to piperidine. After the formation of the ester of the nitrile function.