Heavy metals are natural constituents of the earth's crust, but indiscriminate human activities have drastically altered their geochemical cycles and biochemical balance. This results in accumulation of metals in plant parts having secondary metabolites, which is responsible for a particular pharmacological activity. Prolonged exposure to heavy metals such as cadmium, copper, lead, nickel, and zinc can cause deleterious health effects in humans. Molecular understanding of plant metal accumulation has numerous biotechnological implications also, the long term effects of which might not be yet known.

Nanotoxicology refers to the study of the interactions of nanostructures with biological systems with an emphasis on elucidating the relationship between the physical and chemical properties of nanostructures with induction of toxic biological responses. Nanotoxicology is aimed at providing information on the potential toxicological effects, risk assessment and safety evaluation of nanostructured materials on human health. Nanoparticles present possible dangers, both medically and environmentally. They are also able to pass through cell membranes in organisms and their interactions with biological systems are relatively unknown. Animal studies have shown that nanoparticles can penetrate cells and tissues, move through the body and brain and cause biochemical damage. The greater chemical reactivity of nanomaterials result in increased production of reactive oxygen species which may contribute to similar patterns of cell injury and alterations at the molecular level by initiation, propagation and autocatalytic chain reactions. Intracellular signaling activation and inactivation of enzymes, stimulation, secretion and release of pro-inflammatory cytokines, chemokines and nuclear factor activation and alteration are also common events.

The présent works aims to develop controlled release matrix tablet of diclofenac sodium with modified starch cross linked starch urea as an sustained release polymer and to evaluate the prepared dosage form for physical parameters like weight variation, hardness, friability and drug content. Cross linked starch urea is modified starch introducing desirable alterations in the starch structure so that its behavior is predictable and controllable. In the current study, the influence of different concentration of polymer on erosion of matrix system was studied with a view to develop controlled release formulation of diclofenac sodium. The Diclofenac sodium tablet was prepared by wet granulation method. The result from in vitro drug release study indicated that formulation F1 to F6 were with different polymer concentration and F5 found to release the drug at a steady state over an extended period of time up to 24 h.