Determination of chemical components derived from 2% chlorhexidine gel degradation using gas chromatography-mass spectrometry.
OBJECTIVE
This study determined the chemical components derived from degradation of 2% chlorhexidine (CHX) gel and solution by using gas chromatography-mass spectrometry.


METHODS
Three 2% CHX gels were used to identify the products of CHX gel degradation using gas chromatography-mass spectrometry. A solution of CHX was also evaluated to compare the degradation between gel and solution. Degradation was evaluated in four storage situations (on the worktable with light: on the worktable without light; in the Pasteur oven at 36.5°C without light; and in the refrigerator at 8°C without light). Measurements were made at four time points: initial analysis and 1, 3 and 6 months after. The conversion of CHX into para-chloroaniline in storage situations and in different periods was analyzed statistically using chi-square test (α = 5%).


RESULTS
The 2% CHX gel or solution had already degraded vial found within the period of validity, at all time points and for all storage conditions. The amount of para-chloroaniline (pCA) was directly proportional to time in the case of CHX solution, but not in CHX gel due to lack of homogeneity. CHX homogeneity in hydroxyethylcellulose gel was directly dependent on compounding mode.


CONCLUSIONS
Degradation products, such as para-chloroaniline (pCA), orto- chloroaniline (oCA), meta-chloroaniline (mCA), reactive oxygen species (ROS) and organochlorines (ortho-chlorophenyl isocyanate and 2-amino-5-clorobenzonitrila) were found in 2% CHX gel and solution, regardless of storage conditions or time. In relationship to gel homogenization an alternative to produce 2% CHX gel and a new homogenization method have been developed.
University of São Paulo, Dental School of Ribeirão Preto, Department of Restorative Dentistry , Ribeirão Preto, SP , Brazil.
Samuel Henrique
SH
Câmara De Bem
Carlos
C
Estrela
Débora Fernandes Costa
DF
Guedes
Manoel Damião
MD
Sousa-Neto
Jesus Djalma
JD
Pécora
D000814:Aniline Compounds / Q000032:analysis; D000891:Anti-Infective Agents, Local / Q000032:analysis*; D002482:Cellulose / Q000031:analogs & derivatives / Q000032:analysis; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000032:analysis; D002845:Chromatography / Q000379:methods; D003080:Cold Temperature; D003624:Darkness; D004339:Drug Compounding; D004356:Drug Storage; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D005782:Gels; D006358:Hot Temperature; D006801:Humans; D017953:Isocyanates / Q000032:analysis; D008027:Light; D008422:Materials Testing; D009570:Nitriles / Q000032:analysis; D017382:Reactive Oxygen Species / Q000032:analysis; D012388:Root Canal Irrigants / Q000032:analysis*; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013997:Time Factors
D000814:Aniline Compounds; D000891:Anti-Infective Agents, Local; D005782:Gels; D017953:Isocyanates; D009570:Nitriles; D017382:Reactive Oxygen Species; D012388:Root Canal Irrigants; D012996:Solutions; C031392:3-chloroaniline; D002482:Cellulose; C002283:hydroxyethylcellulose; C025257:2-chloroaniline; C534154:2-amino-5-chlorobenzonitrile; C010882:chlorhexidine gluconate; D002710:Chlorhexidine; C452229:chlorophenyl isocyanate; C004658:4-chloroaniline
chlorhexidine; chlorhexidine gel degradation; gas chromatography; para-chloroaniline; reactive oxygen species