Transdermal delivery of nitric oxide from diazeniumdiolates

Adverse physiological effects can often interfere with the use of nitric oxide (NO) as a therapeutic agent, especially when it is systemically generated from prodrugs. NO which is generated and delivered site-specifically by transdermal donors may be useful in the treatment of parasitic, bacterial or viral skin infections without causing systemic side effects. Three diazeniumdiolates (formerly "NONOates"), including two water soluble compounds, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]-diazen-1-ium-1,2-diolate (DETA-NO) and (Z)-1-[N-(3-aminopropyl)-N-(3-ammoniopropyl)amino]-diazen-1-ium-1,2-diolate (DPTA-NO), and one insoluble compound, DPTA-NO grafted to dextran microspheres (DPTA-NO-g-dextran) were used to transdermally deliver NO to rats. Dextran microspheres were obtained by simultaneously grafting DPTA-NO to dextran and cross-linking dextran with CNBr in an oil-water emulsion. Suspended in hydrogel, DETA-NO, DPTA-NO, and DPTA-NO-g-dextran were applied three times to depilated rats at 4 day intervals. Results show that metabolic urinary nitrate levels increase with time (24-48 h), reach a maximum, and return to baseline by the fourth day. DPTA-NO applications produced an average maximum nitrate level of 94.2 mu mol/day+/-34.2 mu mol S.D. compared to the average maximum nitrate level of 39.8 mu mol/day+/-8.6 mu mol S.D. obtained from treatment with DETA-NO. These results suggest that DPTA-NO delivered NO more efficiently than DETA-NO. When DPTA-NO-g-dextran microspheres were used as the NO donor, results comparable to DPTA-NO were observed with an average maximum nitrate level of 14.9 mu mol/day+/-3.0 mu mol S.D.. These and other conclusive data indicate that, via these diazeniumdiolates, NO can be delivered effectively through rat skin. (C) 1998 Elsevier Science B.V.