Experiences with Phenothiazine as a Urinary Antiseptic

PHENOTHIAZINE is the parent substance of the thiazine dyes, and has a chemical formula closely related to methylene blue. Oral administration results in the urinary excretion of phenothiazine and its two oxidation products, thionol and leucothionol, part of the leucothionol being in some loose chemical combination. Leucothionol is spontaneously oxidized to thionol, which imparts the characteristic red colour to the urine, and gives it its bactericidal properties. Thionol-leucothionol is a reversible oxidation-reduction system similar to methylene blue and its leuco base. Thomas, DeEds and Eddy, of San Francisco, showed the bactericidal properties of urine containing thionol, and because of the low toxicity after oral administration of phenothiazine, as shown by growth curves and blood picture changes, DeEds, Stockton and Thomas (1939) considered it justifiable to undertake clinical trials with it. They carried out this trial on two groups of patients. The first group of 61 patients was given phenothiazine alone. The second group of 31 patients was given phenothiazine in combination with ammonium chloride. The acid reaction of the urine, especially in the pH range of 45-555, facilitated the liberation of the leucothionol held in combination, and this oxidized to thionol increased the active bactericidal properties of the urine.