ProductionThe complete process of coal tar production is shown in Figure 1. Coal tar is produced by carbonization of coal. In this process, the coal is heated to 900-1,100ºC and the vapors released are condensed to form a liquid, from which the ammonia is removed to obtain a black, viscous raw coal tar. The composition of the tar thus obtained depends on the origin and composition of the raw material used, viz. bituminous coal (soft), anthracite (hard) (Arnold 1997, Thami 2002). Raw coal tar can be further purified using various techniques viz. solvent extraction, fractional distillation or column chromatography. Extraction of raw coal tar with alcohol containing 5% w/w Tween 80 produces Liquor carbonis detergents (LCD). Similarly, the distillate and residue obtained after fractional distillation of CCT are called coal tar creosotes and coal tar pitch, respectively. Creosotes consist of light oils (2 to 8%), medium oils (8 to 10%), heavy oils (8 to 10%), and anthracene oils (16 to 20%) (Gosselin et al. Pitch is primarily composed 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 characteristics Raw coal tar is a black, viscous liquid. It has a foul, naphthalene-like odor and a pungent, burning taste (Gennaro, 1990). It's heavier than water. It is “practically insoluble” in water, whereas “almost all” dissolves in benzene or nitrobenzene (Budavari 1989). According to EPA 1994 and IARC 1985, CCT contains approximately 10,000 compounds consisting 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 article ......rmulation in mice (Bhatia 2009, 2011). The therapeutic benefits of coal tar coal tar are as follows: results from the synergistic or additive effects of its more than a thousand chemical constituents whose concentrations vary depending on the source and distillation conditions. There are also no compendial requirements for any sample of coal tar. coal must answer. There is no specific analytical technique to detect variations in constituents. The disadvantages associated with the currently used techniques, namely HPLC and GC, therefore, the development of a. Inexpensive and highly sensitive analytical method, capable of detecting minute changes in the composition of coal tar, will be useful in product control, ensuring uniform safety and effectiveness of the drug product. ConclusionThe safety and effectiveness of coal tar in the treatment of mild to moderate psoriasis are well documented.