In olden days the drug product can be injected in to the infusion bottle and then the mixed drug solution can be injects to the patient. In this process may be there is a chance for the contamination of the drug product. To prevent this problem now days development of infusion premix with 5% dextrose or 0.9% NaCl in single use flexible infusion bags (pvc, pp, polyolefin) avoids further dilutions of the drugs prior to administration. These infusions are the sterile preparations. These can be administered to the patient by intravenous route. The main accept in this infusion solutions is osmolarity of the solution. It should be equal to the blood osmolarity. In these infusions active drug and isotonicity agent are main components. The active dug will shows the pharmacological action and tonicity agent to maintain the isotonicity of the solution. The filling and sterilization of the solutions is also an key point. The solutions can be filled in flexible infusion bags, like pvc, pp, polyolefin. The bag can be selected based on the drug. After filling the bags can be sterilized to prevent the contamination of the product and to kill the microorganisms. Mostly these infusion bags are sterilized by Eto sterilization and gamma sterilization.