Methadone

Methadone
	Skeletal formula of methadone's enantiomers. (S) corresponds to the D-enantiomer, and (R) corresponds to the L-enantiomer.
Clinical data
Trade names	Dolophine, Methadose, Methatab, others
AHFS/Drugs.com	Monograph
MedlinePlus	a682134
License data	US DailyMed: Methadone;
Pregnancy; category	AU: C;
Addiction; liability	High
Routes of; administration	By mouth, intravenous, insufflation, sublingual, rectal
Drug class	Opioid
ATC code	N02AC52 (WHO) N07BC02 (WHO) QN02AC90 (WHO);
Legal status
Legal status	AU: S8 (Controlled drug); BR: Class A1 (Narcotic drugs); CA: Schedule I; DE: Anlage III (Special prescription form required); NZ: Class B; UK: Class A; US: Schedule II;
Pharmacokinetic data
Bioavailability	Rectal: 76% SC: 79% ; Oral: 41–99% IV/IM: 100%
Protein binding	85–90%
Metabolism	Liver (CYP3A4, CYP2B6 and CYP2D6-mediated)
Onset of action	Rapid
Elimination half-life	15–55 hours
Duration of action	Single dose: 4–8 h; Prolonged use:; • Withdrawal prevention: 1–2 days; • Pain relief: 8–12 hours
Excretion	Urine, faeces
Identifiers
	IUPAC name (RS)-6-(dimethylamino)-4,4-diphenylheptan-3-one;
CAS Number	76-99-3 ;
PubChem CID	4095;
IUPHAR/BPS	5458;
DrugBank	DB00333 ;
ChemSpider	3953 ;
UNII	UC6VBE7V1Z;
KEGG	D08195 ;
ChEBI	CHEBI:6807 ;
ChEMBL	ChEMBL651 ;
CompTox Dashboard (EPA)	DTXSID7023273 ;
ECHA InfoCard	100.000.907
Chemical and physical data
Formula	C21H27NO
Molar mass	309.453 g·mol−1
3D model (JSmol)	Interactive image;
	SMILES CCC(C(C1=CC=CC=C1)(C2=CC=CC=C2)CC(N(C)C)C)=O;
	InChI InChI=1S/C21H27NO/c1-5-20(23)21(16-17(2)22(3)4,18-12-8-6-9-13-18)19-14-10-7-11-15-19/h6-15,17H,5,16H2,1-4H3 ; Key:USSIQXCVUWKGNF-UHFFFAOYSA-N ;
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Methadone, sold under the brand names Dolophine and Methadose among others, is a synthetic opioid used medically to treat chronic pain and opioid use disorder. Prescribed for daily use, the medicine relieves cravings and opioid withdrawal symptoms. Withdrawal management using methadone can be accomplished in less than a month, or it may be done gradually over a longer period of time, or simply maintained for the rest of the patient's life. While a single dose has a rapid effect, maximum effect can take up to five days of use. After long-term use, in people with normal liver function, effects last 8 to 36 hours. Methadone is usually taken by mouth and rarely by injection into a muscle or vein.

Side effects are similar to those of other opioids. These frequently include dizziness, sleepiness, nausea, vomiting, and sweating. Serious risks include opioid abuse and respiratory depression. Abnormal heart rhythms may also occur due to a prolonged QT interval. The number of deaths in the United States involving methadone poisoning declined from 4,418 in 2011 to 3,300 in 2015. Risks are greater with higher doses. Methadone is made by chemical synthesis and acts on opioid receptors.

Methadone was developed in Germany in the late 1930s by Gustav Ehrhart and Max Bockmühl. It was approved for use as an analgesic in the United States in 1947, and has been used in the treatment of addiction since the 1960s. It is on the World Health Organization's List of Essential Medicines.