A Comparison of the Antimicrobial Activities of Noxythiolin and Formaldehyde Solutions

Abstract

SUMMARY The availability of a rapid and highly specific polarographic method of analysis for formaldehyde enabled investigation of the rate of formaldehyde release from noxythiolin solutions and actual concentrations of formaldehyde in solutions during clinical use and storage. The antimicrobial activity of noxythiolin solutions, equivalent pure formaldehyde solutions and N‐methylthiourea individually or in combination was examined against standard bacteriological strains and clinical isolates. Several interesting observations were made. Clinical isolates were found to be relatively susceptible to noxythiolin in contrast to laboratory strains. The growth phase of the organism radically affects activity, early exponential phase cells being susceptible to 1.0% noxythiolin. Levels of formaldehyde detected in fresh noxythiolin solutions are extremely low and would not appear to be solely responsible for the antimicrobial activity observed.

Differential Pulse Polarographic Determination of Formaldehyde in Stored Noxythiolin Solutions

“…Similar concentrations of formaldehyde were reported by the polarographic method when amethocaine was present (Noxyflex), the local anaesthetic being polarographically inactive under the conditions chosen. It is interesting to note that, though the bacteriostatic concentration of formaldehyde is O.O02q/; w/v (23), the low formaldehyde concentrations reported here are not sufficient to account for the cidal action of noxythiolin observed in vitro (2,24).…”

Uptake of noxythiolin by a urinary isolate of Escherichia coli

“…Nevertheless, it is clear from the results presented that noxythiolin is adsorbed by E . coli and this could explain the greater antimicrobial action of noxythiolin solutions when compared with equivalent formaldehyde solutions (Gorman et al 1985).…”

“…Recent research has suggested that the degradation products of noxythiolin only contribute to some extent to the overall antimicrobial activity of the compound. For example, it has been shown that Nmethylthiourea, at concentrations found during clinical contact, had no bactericidal activity whereas the small amounts of formaldehyde present were not sufficient to account for the cidal activity of noxythiolin (Gorman et al 1985). Therefore, it would seem likely that noxythiolin itself must contribute to the antimicrobial action.…”

The Contributions of the Celtic Masters and Their Associates

“…This is demonstrated by his early work in improving the chemical and microbiological stability of temazepam [16,17], the use of noxythiolin in stabilizing parenteral formulations [18,19,20,21,22] and various studies exploring the stability of a range of pharmaceutical products against microbial contamination [22,23,24,25,26,27,28,29]. …”