Meperidine

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 B 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
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 is in Schedule II of the Controlled Substances Act 1970 of the United States as a Narcotic with ACSCN 9230 with a 6250 kilo aggregate manufacturing quota as of 2014. The free base conversion ratio for salts includes 0.87 for the hydrochloride and 0.84 for the hydrobromide. The A, B, and C intermediates in production of pethidine are also controlled, with ACSCN being 9232 for A (with a 6 gramme quota) and 9233 being B (quota of 11 grammes) and 9234 being C (6 gramme quota). It is listed under the Single Convention for the Control of Narcotic Substances 1961 and is controlled in most countries in the same fashion as is morphine.