ProductionThe complete process of coal tar production is shown in Figure 1. Coal tar is produced by carbonization of coal. In this process, coal is heated to 900-1100 ºC and the developed vapors are condensed to form a liquid, from which ammonia is removed to obtain a viscous, black raw coal tar. The composition of the tar thus obtained depends on the origin and composition of the starting material used, i.e. bituminous coal (soft), anthracite (hard) (Arnold 1997, Thami 2002). Raw coal tar can be further purified using various techniques, e.g. solvent extraction, fractional distillation or color chromatography. Extraction of raw coal tar with alcohol containing 5% w/w Tween 80 produces Liquor carbonis detergens (LCD). Similarly, the distillate and residue obtained after fractional distillation of CCT are known as coal tar creosotes and coal tar pitch, respectively. Creosotes consist of light oils (2-8%), medium oils (8-10%), heavy oils (8-10%), and anthracene oils (16-20%) (Gosselin et al. 1984). Pitch consists primarily of highly condensed aromatic hydrocarbons (Kershaw 1993). Medical pix lithantracis is a mixture of pitch (66.67%) and tar oils (33.33%) (Roelofzen 2007). Physical and chemical characteristicsRaw coal tar is a black, viscous liquid. It has an unpleasant odor similar to naphthalene and a pungent and burning taste (Gennaro1990). It is heavier than water. It is “practically insoluble” in water, while “all or almost all” dissolves in benzene or nitrobenzene (Budavari 1989). According to EPA 1994 and IARC 1985, CCT contains approximately 10,000 compounds made up of 48% hydrocarbons, 42% carbon and 10% water. The chemical composition of coal tar depends on the distillation temperature (IARC Monogr Eval C...... middle of paper ......rmulation in mice (Bhatia 2009, 2011). The therapeutic benefits of coal tar are the results of the synergistic or additive effects of its more than one thousand chemical constituents whose concentrations vary depending on the source and distillation conditions. Furthermore, there is no additional requirement that any coal tar sample must meet. There is no specific analytical technique capable of detecting changes in the constituents. The disadvantages associated with the currently used techniques, namely HPLC and GC, are the problem. Therefore, the development of a low-cost and highly sensitive analytical method capable of detecting the slightest alterations in the composition of coal tar will be useful. product control, ensuring uniform safety and efficacy of the drug product. Conclusion The safety and efficacy of coal tar in mild to moderate psoriasis are well documented.