quantities; humans, dogs, and most other species produce the R(+) enantiomer more (with the human AUC ratio being 80:20). Compared to the S(-) enantiomer, the R(+) has greater pharmacological activity, lasts longer in the bloodstream, is found in higher concentrations in the infected host tissues, and is found in higher concentrations within the parasites themselves. Some albendazole is also converted to hydroxyalbendazole, mainly by CYP2J2. For systemic parasites, albendazole acts as a prodrug, while albendazole sulfoxide reaches systemic circulation and acts as the real antihelminthic. Albendazole sulfoxide is able to cross the blood–brain barrier and enter the cerebrospinal fluid at 43% of plasma concentrations; its ability to enter the central nervous system allows it to treat neurocysticercosis. Albendazole sulfoxide is converted to the inactive albendazole sulfone by cytochrome P450 oxidases, thought to include CYP3A4 or CYP2C. Other inactive metabolites include: 2-aminosulfone, ω-hydroxysulfone, and β-hydroxysulfone. The major final metabolites that are excreted by humans are: methyl [5-(propylsulfonyl-1H-benzimidazol-2-yl)] carbamate, methyl [6-hydroxy 5-(n-propylsulfonyl)-1H-benzimidazole-2-yl)] carbamate, methyl [5-(n-propylsulfinyl)-1H-benzimidazole-2-yl)] carbamate, 5-(n-propylsulfonyl)-1H-benzimidazole-2-yl amine, and 5-(n-propysulfinyl)-1H-benzimidazole-2-yl amine. There are also some minor hydroxylated sulfated or glucuronidated derivatives. No unchanged albendazole is excreted, as it is metabolized too quickly. In humans, the metabolites are excreted mostly in bile, with only a small amount being excreted in urine (less than 1%) and feces. In ruminants, 60–70% of the metabolites are excreted in urine. Like all benzimidazoles, albendazole has no residual effect, and thus protects poorly against reinfestations. History Albendazole, patented in 1975, was invented by Robert J. Gyurik and Vassilios J. Theodorides and assigned to SmithKline Corporation. It was introduced in 1977 as an antihelminthic for sheep in Australia, and was registered for human use in 1982. Society and culture Brand names Brand names include: Albenza, Alworm, Andazol, Eskazole, Noworm, Zentel, Alben-G, ABZ, Cidazole, Wormnil etc. Economics The pharmaceutical company Amedra increased the price after purchasing the rights to the drug, instead of lowering it as generics are predicted to do, drawing criticism from patients' rights advocates. In 2013, GlaxoSmithKline donated 763 million albendazole tablets for the treatment and prevention of parasitic infections in developing countries, bringing the total to over 4 billion tablets donated since 1998. Research Albendazole and related compounds or metabolites like albendazole sulfone (ALB-SO2) exhibit antibacterial effects via an unknown, possibly FtsZ-related, mechanism. It inhibits division of Wolbachia and Mycobacterium tuberculosis, turning them into a long "filament" shape as they grow and fail to divide. Since