The invention provides a method of enhancing the action of a pharmaceutical agent selected from the group consisting of the anti-infective agents, the group comprising of the antimicrobial agents, the anthelmintic agents and the anti-ectoparasitic agents, but excluding coal tar solution and H1-antagonist antihistamines, and from the group consisting of the CPNS agents selected from the group of compounds acting on the central or peripheral nervous system, but excluding coal tar solution and H1-antagonist antihistamines and also excluding anti-inflammatory, analgesic and antipyretic agents and also provides an enhanced method for the administration of a nucleic acid substance to the cells of an animal, a plant or a micro-organism. The method is characterised in that the agent or nucleic acid substance is formulated with an administration medium which comprises a solution of nitrous oxide gas in a pharmaceutically acceptable carrier solvent for the gas and which administration medium includes at least one fatty acid or ester or other suitable derivative thereof selected from the group consisting of oleic acid, linoleic acid, alpha-linolenic acid, gamma-linolenic acid, arachidonic acid, eicosapentaenoic acid [C20:5ω3], decosahexaenoic acid [C22:6ω3], ricinoleic acid and derivatives thereof selected from the group consisting of the C1 to C6 alkyl esters thereof, the glycerol-polyethylene glycol esters thereof and the reaction product of hydrogenated natural oils composed largely of ricinoleic acid based oils, such as castor oil with ethylene oxide. The formulations of such agents or substances form part of the invention
