Saving the ischemic penumbra: potential role for statins and phosphodiesterase inhibitors.

Ischemic stroke is the third cause of death and the most common cause of neurological disability. A main target of treatment is the still salvageable tissue surrounding the core of infarction and called "ischemic penumbra". Up to now the only drug approved for the treatment of acute ischemic stroke is recombinant tissue plasminogen activator to achieve early arterial recanalization and hypoxic tissue reperfusion and improve neural function. However, thrombolytic therapy has to be administered soon after the event since its efficacy is time dependent. This intervention also carries an increased risk of hemorrhagic transformation. In the rescue of poorly perfused cerebral regions an important role is played by collateral blood supply through the circle of Willis and through small pial vessels surrounding the lesion. The extent of collateralization is variable and at least in part regulated by the modulation of arteriolar nitric oxide (NO)-dependent endothelial function. Drugs that can improve endothelial function and cerebrovascular reactivity could have a role in collateral formation and infarct volume limitation. Statins affect endothelial NO production demonstrating their potential to influence endothelial NO synthase (eNOS) and in treating stroke. Phosphodiesterase (PDE) inhibitors improve functional recovery after stroke in rats enhancing neuro and synapto genesis and increasing guanosine 3,5-cyclic monophosphate (cGMP). The aim of this review is to highlight the potential of these two classes of drugs in the treatment of acute ischemic stroke by analysing their pharmacological effects and involvement in the NO and cGMP pathways.