Clemizole

Originator

Allercur,Roerig,US,1960

Definition

ChEBI: A member of the class of benzimidazoles that is 1H-benzimidazole substituted by a pyrrolidin-1-ylmethyl and a 4-chlorobenzyl groups at positions 2 and 1 respectively.

Manufacturing Process

From 13.1 g of N-p-chlorobenzyl-2-nitroaniline (MP 110°C, obtained in the form of orange-red needles, from o-nitrochlorobenzene and pchlorobenzylamine by reaction for 3 hours at 150°C) by reduction with Raneynickel and hydrogen, in which reaction the substance may be suspended in methanol or dissolved in methanol-ethyl acetate at normal pressure and at about 40°C with combination of the theoretical quantity of hydrogen, 12.2 g are obtained of o-amino-N-p-chlorobenzylaniline, which after recrystallization from aqueous methanol has a MP of 90°C.
8 g of o-amino-N-p-chlorobenzylaniline and 2.8 g of pyridine are dissolved in dry ether and reacted with an ethereal solution of 3.9 g of chloracetyl chloride with cooling in a mixture of ice and common salt. 8 g of N-p-chlorobenzyl-N'- chloracetyl-o-phenylene diamine are obtained which can be worked up in the form of the crude product and, in the slightly colored form, has a MP of 130°C.
7.6 g of this compound are boiled with 3.9 g of pyrrolidine in 70 cc of toluene for some hours under reflux. After extraction by shaking with water and treatment with hydrochloric acid the hydrochloride is produced of N-pchlorobenzyl-N'-pyrrolidylacetyl-o-phenylene diamine together with some 1-pchlorobenzyl-2-N-pyrrolidylmethyl-benzimidazole. The former, after recrystallization from butanol, melts with foaming at 205°C, the latter, after recrystallization from butanol melts at 239°C to 241°C, and is in the form of white microscopic rods. Boiling in nitrobenzene converts the former compound into the latter.

Therapeutic Function

Antihistaminic

Biological Activity

the ns4b protein is a key player in hcv replication. disrupting ns4b function thus represents an attractive new anti-hcv strategy. combining clemizole with other anti-hcv agents could increase the antiviral effect achieved with 1 active drug alone and decrease emergence of viral resistance.

in vitro

although significant, clemizole’s antiviral effect was moderate (50% effective concentration of 8 mm against a hcv genotype 2a clone). clemizole’s antiviral effect was highly synergistic with the hcv protease inhibitors vx950 and sch503034, without toxicity. in contrast, clemizole combinations with either interferon, ribavirin, or the nucleoside (nm283) and nonnucleoside (hcv796) hcv polymerase inhibitors were additive [1].

in vivo

clemizole had an unexpectedly short plasma half-life; it was very rapidly biotransformed into a glucuronide (m14) and a dealkylated metabolite (m12) and into a variety of lesser metabolites in c57bl/6j mice [2].

References

[1] einav s, sobol hd, gehrig e, glenn js. the hepatitis c virus (hcv) ns4b rna binding inhibitor clemizole is highly synergistic with hcv protease inhibitors. j infect dis. 2010;202(1):65-74.
[2] nishimura t, hu y, wu m, pham e, suemizu h, elazar m, liu m, idilman r, yurdaydin c, angus p, stedman c, murphy b, glenn j, nakamura m, nomura t, chen y, zheng m, fitch wl, peltz g. using chimeric mice with humanized livers to predict human drug metabolism and a drug-drug interaction. j pharmacol exp ther. 2013;344(2):388-96. doi: 10.1124/jpet.112.198697. epub 2012 nov 8.