Transdermally delivered peroxovanadium can lower blood glucose levels in diabetic rats

The element vanadium can have insulin mimetic properties and therefore has been suggested as a possible therapeutic agent for treatment of diabetes. A series of peroxovanadium compounds that are more potent at lowering blood glucose levels than sodium metavanadate, sodium orthovanadate and vanadyl sulfate have recently been synthesized. These compounds probably will not be orally active so transdermal administration is a potential option. A patch containing either the peroxovanadium compound [VO(O2)2 1-10 phenanthroline], abbreviated bpV(phen), or placebo was placed on the back of streptozotocin induced diabetic rats and was delivered either passively (16 h) or iontophoretically (0.5 mA/cm2 for 4 h). Blood samples were analyzed for glucose and vanadium levels. Mean blood glucose levels were 83+/-1% and 109+/-1% of the starting values for animals iontophoretically treated with bpV(phen) and vehicle, respectively. The compound's insulin mimetic properties were evident within 60 min of current initiation. Blood glucose levels were reduced to 74+/-14% of the original level after 16 h of passive treatment. The compound was ineffective when fed to animals. Transdermal delivery of bpV(phen) resulted in significantly greater blood levels of vanadium than the orally delivered compound (P<0.05). Overall these experiments demonstrate that peroxovanadium delivered through the skin can lower blood glucose levels in rats. Further experiments are warranted to better characterize the nature of the response and to determine the potential for using these compounds in humans.