However, none of these therapies are completely safe and effective, and clinical exploration of promising antiviral agents like nucleoside analogues is hampered by their significant side effects, especially the development of resistant viruses. Therefore, it is crucial to explore the safer, more efficacious and less expensive anti-HBV agents. Polyoxometalates are inorganic cluster-like complexes that are constituted from the oxide anion and transition metal cations. These complexes are versatile and can be used in catalytic processes, magnetic materials, nanotechnology and medical procedures. Several POMs are especially useful in Metolazone medicinal chemistry, serving as new kinds of inorganic medicinal candidates that possess antiviral, antitumor, and antibiotic activities. Because of their extremely small dimensions, they exhibit low toxicity, are stable in biological media, are liable to be cleared by the renal system, and can be engineered for various applications, especially as antiviral agents. POMs have been widely researched in recent years, and they have been proven to be active against a wide range of viruses, including both RNA viruses and DNA viruses, such as the human immunodeficiency RNA virus, severe acute Leptomycin A respiratory syndrome RNA virus, influenza RNA virus and herpes simplex DNA virus. The mechanism of antiviral action may occur through the prevention of viral adsorption and penetration by inhibiting the activity of retroviridase. The advantage of POMs in antiviral activity inspired us to find effective anti-HBV drug candidates in this field. Among the various POMs, keggin-type niobium-substitutedheteropolytungstate Cs2K4Na.H2O 1 interested us because of its broad-spectrum antiviral activity, especially for anti-HIV. Compound 1 has been synthesized, purified, and characterized, thereafter its toxicity and antiviral activity against hepatitis B virus were investigated in HepG 2.2.15. The results indicated that Compound 1 exhibits high activity against HBV and low toxicity. Although POMs have been studied for many years, reports of relevant pharmacokinetics studies are relatively rare. There are, however, some papers from the 1990s. The most detailed published investigation of POM pharmacokinetics is that of Ni et al, and the atomic emission spectrometry methods for determination the concentration of POM in rats have already been described by this group.