Pecazine

Mepazine
INN: Pecazine

Clinical data
Trade names	Pacatal, Pacatol, Paxital, Lacumin, Nothiazine
Routes of administration	Oral, parenteral
ATC code	None
Legal status
Legal status	BR: Class C1 (Other controlled substances) US: ℞-only (withdrawn, 21 CFR 216.24)
Identifiers
IUPAC name 10-[(1-methylpiperidin-3-yl)methyl]phenothiazine
CAS Number	60-89-9 2975-36-2 (HCl)
PubChem CID	6075
IUPHAR/BPS	9782
ChemSpider	5850
UNII	PH34873A38
KEGG	D02607
ChEBI	CHEBI:135324
ChEMBL	ChEMBL395110
CompTox Dashboard (EPA)	DTXSID2046177
ECHA InfoCard	100.000.446
Chemical and physical data
Formula	C19H22N2S
Molar mass	310.46 g·mol−1
3D model (JSmol)	Interactive image
SMILES CN1CCCC(C1)CN2C3=CC=CC=C3SC4=CC=CC=C42
InChI InChI=1S/C19H22N2S/c1-20-12-6-7-15(13-20)14-21-16-8-2-4-10-18(16)22-19-11-5-3-9-17(19)21/h2-5,8-11,15H,6-7,12-14H2,1H3 Key:CBHCDHNUZWWAPP-UHFFFAOYSA-N

Pecazine (INN), also known as mepazine (trade name Pacatal), is a phenothiazine formerly used as a neuroleptic drug or major tranquilizer.

Pecazine was first synthesized in 1953 by Wilhelm Schuler and Otto Nieschulz and was quickly incorporated into psychiatric practice as an ataractic, i.e., a true tranquilizer rather than a hypnotic or depressant. It was considered interchangeable with chlorpromazine, albeit with a different side effect profile, which included less sedation and a lower risk of extrapyramidal symptoms due to its potent parasympatholytic and anticholinergic effect.

As early as 1958, however, studies reported inferiority to other phenothiazines in the treatment of schizophrenia and questioned its place in the clinic; in 1960, a double-blind, randomized controlled trial found pecazine to be no more effective than placebo. Subsequent research found that, like the structurally related promethazine, pecazine is essentially devoid of antipsychotic activity.

Pecazine was implicated in a number of cases of agranulocytosis and was subsequently withdrawn from the market. More recently, it has become a subject of research interest as a MALT1 and RANKL inhibitor.