are not limited to gluconic acid logp u2212 3 18 methanesulfonic acid logp u2212 1 89 tartaric acid logp u2212 1 43 malic acid logp u2212 1 26 glycine logp u2212 1 03 lactic acid logp u2212 0 70 and ethylenediamine tetraacetic acid logp u2212 0 43 organic acids not suitable for use in the invention are those with logp in the range of about 2 0 to about 8 5 for example organic acids not suitable for use in the invention include caprylic acid logp 2 90 lauric acid logp 5 03 oleic acid logp 7 70 and steric acid logp 8 22 organic acid u2212 flucytosine addition salts may be prepared by methods known to those with skill in the art an organic acid for example methanesulfonic acid might be dissolved in an organic solvent such as ethanol and the resulting solution might be added to a solution of flucytosine in an organic solvent such as ethanol the resulting mixture might then be heated until homogeneous then cooled and the addition salt isolated by means known in the art such as concentration of the solvent or precipitation or crystallization of the salt by addition of a second organic solvent such as ether it will be understood that the flucytosine addition salt is prepared by mixing equimolar amounts of flucytosine and organic acid it will be appreciated that a flucytosine organic acid salt may also be formed by mixing flucytosine and the organic acid in one.