Analytical Methods for the Determination of Chlorhexidine: A Review

A fast, sensitive, greener, and stability-indicating HPLC method for the standardization and quantitative determination of chlorhexidine acetate in commercial products

The goal of the proposed work was to create and verify a fast, sensitive, greener, and stability-indicating high-performance liquid chromatography (HPLC) method to quantify chlorhexidine acetate (CHDA) in commercial products. The developed method was validated for numerous validation metrics and greenness. The greener mobile phase was made up of a ternary mixture of ethanol, water, and glacial acetic acid (50:49:1 v/v/v). CHDA was detected at a wavelength of 265 nm. The developed HPLC method showed a coefficient of determination of 0.9981 and was linear in the 1–100 µg/mL range. In addition, the developed method for CHDA analysis was rapid, accurate, precise, robust, and sensitive. The outstanding greenness profile was indicated by the derived values of the Analytical Eco-Scale, ChlorTox, and AGREE scales for the current approach, which are 89, 0.74 g, and 0.77, respectively. With its breakdown products present, the proposed analytical approach was still able to identify CHDA, demonstrating its selectivity- and stability-indicating qualities. Two distinct commercial products, A and B, were found to contain 1.96 and 2.05% w/v of CHDA, respectively. These results revealed that CHDA in commercially accessible products can be routinely standardized and quantified using the proposed HPLC approach.

A Novel Polymeric Membrane Sensor for Chlorhexidine Determination

In the present work, potentiometric sensors with polymer membranes used for chlorhexidine (CHXD) determination were developed. The polymer membranes were plasticized with bis(2-ethylheksyl)sebacate (DOS) or 2-nitrophenyloctyl ether (o-NPOE). The active compounds used in the membrane were cyclodextrins, crown ethers, and ion exchangers. The best-constructed electrode was based on neutral heptakis(2,3,6-tri-O-benzoyl)-β-cyclodextrin with lipophilic salt (KTpClBP)-potassium tetrakis(4-chlorophenyl) borate-dissolved in plasticizer, DOS. The presented electrode is characterized by an average cationic slope of 30.9 ± 2.9 mV decade-1 within a linear range of 1 × 10-6 to 1 × 10-3 mol × L-1, while the value of the correlation coefficient is 0.9970 ± 0.0026. The response time was about 5 s when increasing the sample concentration and about 10 s when diluting the sample. The electrode potential is independent of the pH within a range of 4.0-9.5. The polymeric membrane sensor was successfully applied for assays of chlorhexidine digluconate in pure samples and pharmaceutical samples. The relative error from three replicate measurements was determined to be 1.1%. and the accuracy was RSD = 0.3-1.1%.

Characterization of Exposure to Cleaning Agents Among Health Workers in Two Southern African Tertiary Hospitals

BACKGROUND

Whilst cleaning agents are commonly used in workplaces and homes, health workers (HWs) are at increased risk of exposure to significantly higher concentrations used to prevent healthcare-associated infections. Exposure assessment has been challenging partly because many are used simultaneously resulting in complex airborne exposures with various chemicals requiring different sampling techniques. The main objective of this study was to characterize exposures of HWs to various cleaning agents in two tertiary academic hospitals in Southern Africa.

METHODS

A cross-sectional study of HWs was conducted in two tertiary hospitals in South Africa (SAH) and Tanzania (TAH). Exposure assessment involved systematic workplace observations, interviews with key personnel, passive personal environmental sampling for aldehydes (ortho-phthalaldehyde-OPA, glutaraldehyde and formaldehyde), and biomonitoring for chlorhexidine.

RESULTS

Overall, 269 samples were collected from SAH, with 62 (23%) collected from HWs that used OPA on the day of monitoring. OPA was detectable in 6 (2%) of all samples analysed, all of which were collected in the gastrointestinal unit of the SAH. Overall, department, job title, individual HW use of OPA and duration of OPA use were the important predictors of OPA exposure. Formaldehyde was detectable in 103 (38%) samples (GM = 0.0025 ppm; range: <0.0030 to 0.0270). Formaldehyde levels were below the ACGIH TLV-TWA (0.1 ppm). While individual HW use and duration of formaldehyde use were not associated with formaldehyde exposure, working in an ear, nose, and throat ward was positively associated with detectable exposures (P-value = 0.002). Glutaraldehyde was not detected in samples from the SAH. In the preliminary sampling conducted in the TAH, glutaraldehyde was detectable in 8 (73%) of the 11 samples collected (GM = 0.003 ppm; range: <0.002 to 0.028). Glutaraldehyde levels were lower than the ACGIH's TLV-Ceiling Limit of 0.05 ppm. p-chloroaniline was detectable in 13 (4%) of the 336 urine samples (GM = 0.02 ng/ml range: <1.00 to 25.80).

CONCLUSION

The study concluded that detectable exposures to OPA were isolated to certain departments and were dependent on the dedicated use of OPA by the HW being monitored. In contrast, low-level formaldehyde exposures were present throughout the hospital. There is a need for more sensitive exposure assessment techniques for chlorhexidine given its widespread use in the health sector.

Analysis of chlorhexidine gluconate in skin using tape stripping and ultrahigh-performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Topical chlorhexidine gluconate (CHG) is used widely to reduce healthcare-associated infection. The optimal therapeutic dose for maximum efficacy and reduced toxicity is unclear, in part because of the lack of analytical methods to monitor CHG levels in skin. A novel method was developed to accurately measure CHG levels in skin after topical application with the goal of determining its pharmacokinetics in skin.

METHODS

Ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to develop a validated assay for measuring CHG levels in skin cells collected by a non-invasive adhesive tape-stripping method. CHG levels in the skin stratum corneum of healthy adult volunteers were measured at 0.5, 4, 8, and 24 h after its application.

RESULTS

Conditions for extraction of CHG were optimized and the assay was linear in the range 0.1-50 μg/mL (corresponding to 0.2-100 μg chlorhexidine/tape), with an intra-assay precision of 1.74-10.50 % and a relative error of ≤10 %. The inter-assay accuracy was in the range of 5.86-10.96 % with a relative error <9 %. CHG was stable on tapes stored at 4 °C and ambient temperature for 14 and 3 days, respectively. The recovery of CHG from the tape was quantitative and the matrix effect was determined as 2.1-14.8 %. CHG levels in healthy adult volunteer skin following topical application decreased rapidly over a 24 h period.

CONCLUSIONS

A rapid, accurate and specific UHPLC-MS/MS method was developed for the measurement of CHG in the skin obtained by tape stripping that was linear over a large dynamic range. This assay afforded a simple and convenient non-invasive approach to monitor CHG levels in skin after topical application that can be applied to enable the optimal dose to prevent infection and minimize toxicity.

Determination of chlorhexidine retention in different oral sites using matrix-assisted laser desorption/ionization-time of flight mass spectrometry

OBJECTIVE

The aim of this study was to determine chlorhexidine retention in different oral sites after a one-time 30 s mouth rinsing.

DESIGN

Five volunteers were asked to rinse their mouth with 10 ml of 0.2 % chlorhexidine digluconate for 30 s. After rinsing, samples were collected from the interdental area, buccal dental pellicle, anterior labial and posterior buccal mucosa, and saliva with a microbrush at five-time points within 24 h. Retention of chlorhexidine was measured using matrix-assisted laser desorption/ionization-time of flight mass spectrometry with a quantification limit of 15 ng/ml.

RESULTS

Chlorhexidine remained in the oral cavity at micrograms per milliliter levels for 11 h after mouth rinsing and was even detected 24 h after application. The results showed a distinct decline of intraoral chlorhexidine levels during the first 6 h after rinsing and it was then retained at low concentrations for at least 24 h.

CONCLUSIONS

The dental pellicle and oral mucosa were favorable sites for chlorhexidine retention. The novel method used for chlorhexidine determination offered excellent quantification limits and readily permitted quantification of chlorhexidine.

Lethal and sub lethal effects of the biocide chlorhexidine on aquatic organisms

Chlorhexidine is among the most used biocides in Europe, however its toxicity to aquatic organisms is scarcely known. The main objective of this study was to assess the lethal and sub lethal effects of chlorhexidine digluconate (ChD) on four aquatic model organisms: the bacteria Vibrio fischeri, the algae Pseudokirchneriella subcapitata, the crustacean Daphnia magna and the embryos of the fish Danio rerio. ChD was very toxic to algae and crustaceans, with a 72 h-EC50 of 62.2 μg/l and a 48 h-EC50 of 45.0 μg/l, respectively. Toxicity to fish embryos and the bacteria was lower, with a 96 h-EC50 of 804.0 μg/l and a 15 min-EC50 of 1,694.0 μg/l, respectively. Concerning sub lethal effects on D. magna (feeding inhibition) a 6 h-EC50 of 503.7 μg/l was obtained. In fish, ChD caused developmental abnormalities, namely alterations in the amniotic fluid (48 h-EC20 of 753.6 μg/l) and early hatching. Moreover, enzymatic biomarkers on fish embryos showed an induction of cholinesterase activity in all ChD tested concentrations (80-900 μg/l). The catalase activity was also induced at the highest concentration tested (900 μg/l) whereas no changes were observed for glutathione-S-transferase and lactate dehydrogenase activities. The toxicity of ChD to the algae and crustacean raises concerns about its potential effects in aquatic food webs, since these organisms are in the base of trophic chains, and highlights the need for further studies on ChD toxicity to aquatic organisms.

Development and validation of a microbiological assay for determination of chlorhexidine digluconate in aqueous solution

Chlorhexidine (CHX) is a broad-spectrum antiseptic that is used in many topical pharmaceutical formulations. Because there is no official microbiological assay reported in the literature that is used to quantify CHX, this paper reports the development and validation of a simple, sensitive, accurate and reproducible agar diffusion method for the dosage of chlorhexidine digluconate (CHX-D) in an aqueous solution. The assay is based on the inhibitory effect of CHX-D upon the strain of Staphylococcus aureus ATCC 25923, which is used as the test microorganism. The design 3x3 parallel-line model was used. The results were treated statistically by analysis of variance (ANOVA), and they were excellent in terms of linearity (r = 0.9999), presenting a significant regression between the zone diameter of growth inhibition and the logarithm of the concentration within the range of 0.5 to 4.5%. The results obtained were precise, having relative standard deviations (RSD) for intra-day and inter-day precision of 2.03% and 2.94%, respectively. The accuracy was 99.03%. The method proved to be very useful and appropriate for the microbiological dosage of CHX-D in pharmaceutical formulations; it might also be used for routine drug analysis during quality control in pharmaceutical industries.

Dual delivery of chlorhexidine and platelet-derived growth factor-BB for enhanced wound healing and infection control

Wound treatment can require molecules that both enhance healing and control infection. As in many biomedical applications, the options for therapeutic molecules may include both hydrophilic and hydrophobic molecules. The goal of this study was to investigate a polymer system for drug delivery that simultaneously delivers platelet-derived growth factor (PDGF)-BB, a hydrophilic protein known to promote wound healing, and chlorhexidine (CHX), a hydrophobic antimicrobial agent for infection treatment. Poly(lactic-co-glycolic acid) (PLGA) microspheres were prepared using different polymer formulations in a double emulsion process. CHX encapsulation efficiency was 19.6±0.8% and 28.9±1.5% for PLGA 50:50 and 85:15, respectively. The presence of CHX significantly increased PDGF-BB encapsulation efficiency relative to PDGF-BB alone. Both molecules could be released for up to 50 days and exhibited bioactivity for greater than 3 (PLGA 85:15) or 8 (PLGA 50:50) weeks using in vitro bacteria and cellular assays. An infected wound model was used to evaluate the system in vivo. Wounds treated with the dual delivery system showed decreased levels of infection and increased healing. Vascular analysis of wound tissues also showed higher levels of mature vasculature with the delivery of PDGF-BB. In conclusion, we have evaluated a drug delivery system for simultaneous delivery of hydrophobic and hydrophilic molecules and have shown that this system can improve healing and reduce bacteria levels in an infected wound model. This system could be applied to other therapeutic applications where sustained delivery of hydrophobic and hydrophilic molecules is required.

Quantitative analysis of skeletal symmetric chlorhexidine in rat plasma using doubly charged molecular ions in LC–MS/MS detection

Background: The skeletal symmetric structure of chlorhexidine predicts that each doubly charged molecular ion may generate two para-chlorbenzenguanidines daughter ions through bond cleavage at two protonation sites, thus generating better sensitivity in MRM transition than that involving singly charged molecular ions. This unique nature can be used to improve sensitivity of a LC–MS/MS method. Results: High-throughput LC–MS/MS was developed and validated to quantify chlorhexidine in rat plasma as low as 0.500 ng/ml. In the method, a unique chromatographic method on a narrow bore column reduced run time to 2.5 min and successfully minimized high background from accumulation of endogenous compounds in matrix on the column. Conclusion: This method was proved to be robust and suitable to support rat dermal toxicology studies.