In some serious clinical conditions there is need to reach the target plasma concentration rapidly. Therefore a high dose called loading dose is given for once followed by usual maintenance dose to avoid reaching the toxic concentration

Different drugs pass through four major pharmacokinetic processes in the body; absorption, metabolism, distribution and finally elimination.

Volume of distribution measure the ability of various drugs with different sizes and charges to distribute through body fluids. Apparent volume of distribution Vd is calculated by dividing the amount of the drug administered on the plasma concentration of