Methylene blue, an old drug with new indications?

Adriana Miclescu, L. Wiklund

Department of Surgical Sciences/Anesthesiology and Intensive Care Medicine, Uppsala University Hospital

Abstract

Just when we thought we finally understood methylene blue (MB) after it has been used clinically for more than a century, the old properties are revived and therefore possible new indications appears. Nitric oxide (NO) stimulates soluble guanylate cyclase, which converts guanosine triphosphate into cyclic guanosine monophosphate. Increases in cGMP concentration, in turn, through a cascade of protein kinases, induce smooth muscle relaxation and vasodilatation. Methylene blue (MB) has direct inhibitory effects on nitric oxide synthases (NOS), both constitutive and inducible and blocks accumulation of cyclic guanosine monophosphate (cGMP) by inhibiting the enzyme guanylate cyclase. Also, MB blocks the iron-containing enzymes such as xanthine oxidase and has antioxidants effects. New indications are therefore described in relation with MB as in the vasoplegic syndrome following cardiopulmonary bypass in humans and in the settings of cardiac arrest in animals.

Keywords: methylene blue, oxidative injury, neuroprotection, hemodynamics, cardiopulmonary resuscitation

J Rom Anest Terap Int 2010; 17: 35-41

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