Uptake and retention of 65Zn in lithium-treated rat liver: role of zinc

A Review for Lithium: Pharmacokinetics, Drug Design, and Toxicity

Lithium as a mood stabilizer has been used as the standard pharmacological treatment for Bipolar Disorder (BD) for more than 60 years. Recent studies have also shown that it has the potential for the treatment of many other neurodegenerative disorders, including Alzheimer's, Parkinson's and Huntington's disease, through its neurotrophic, neuroprotective, antioxidant and anti-inflammatory actions. Therefore, exploring its pharmacokinetic features and designing better lithium preparations are becoming important research topics. We reviewed many studies on the pharmacokinetics, drug design and toxicity of lithium based on recent relevant research from PubMed, Web of Science, Elsevier and Springer databases. Keywords used for searching references were lithium, pharmacology, pharmacokinetics, drug design and toxicity. Lithium is rapidly and completely absorbed from the gastrointestinal tract after oral administration. Its level is initially highest in serum and then is evidently redistributed to various tissue compartments. It is not metabolized and over 95% of lithium is excreted unchanged through the kidney, but different lithium preparations may have different pharmacokinetic features. Lithium has a narrow therapeutic window limited by various adverse effects, but some novel drugs of lithium may overcome these problems. Various formulations of lithium have the potential for treating neurodegenerative brain diseases but further study on their pharmacokinetics will be required in order to determine the optimal formulation, dosage and route of administration.

Altered uptake and biological half-lives of 65Zn on arsenic exposure--modulation by zinc treatment

The present study revealed the effects of zinc on the biokinetics of (65)Zn in rats following arsenic intoxication. The animals were segregated into four groups: group I--untreated controls, group II--arsenic treated (100 ppm as NaAsO(2) in drinking water), group III--zinc treated (227 mg ZnSO(4) per liter drinking water), and group IV--arsenic + zinc treated. Each rat was injected intraperitoneally with 1.85 MBq radioactivity of (65)Zn following 3 months of different treatments, and the radioactivity was determined using a suitably shielded scintillation counter. Arsenic treatment showed a significant increase in the fast component (Tb(1)) of the biological half-life of (65)Zn in liver, which remained unaltered in the whole body. Furthermore, arsenic treatment decreased significantly the slow component (Tb(2)) in the whole body, which remained unchanged in the liver. However, zinc supplementation to arsenic-treated rats normalized Tb(1) in the liver, but caused no change in Tb(2) in the whole body. Furthermore, the uptake values of (65)Zn were significantly increased in the liver, brain, kidney, and intestine following arsenic treatment, and the values in the liver and brain were decreased by zinc. Hence, zinc plays a significant role in regulating the biokinetics of (65)Zn in the liver and the whole body of arsenic-intoxicated rats.