Dendrimer-mediated permeation enhancement of chlorhexidine digluconate: Determination of in vitro skin permeability and visualisation of dermal distribution

doi:10.1016/j.ejpb.2020.12.014

European Journal of Pharmaceutics and Biopharmaceutics

Volume 159, February 2021, Pages 77-87

https://doi.org/10.1016/j.ejpb.2020.12.014 Get rights and content

Abstract

Chlorhexidine digluconate (CHG) is a cationic bisbiguanide used in the UK as the first-line skin antiseptic prior to surgery in the UK due to its favourable efficacy and safety profile, high affinity for skin binding and minimal reports of resistance. Despite this, bacteria remain within deeper skin layers, furrows and appendages that are considered inaccessible to CHG, due to its poor dermal penetration. In this study a third generation, polyamidoamine dendrimer (G3 PAMAM-NH₂) was utilised to improve dermal penetration of CHG. A topical gel formulation was optimised to maximise CHG delivery (containing 0.5% gelling agent and 4% drug), followed by drug and dendrimer co-formulation into a commercially viable gel. The gel containing 4% CHG and 1 mM PAMAM dendrimer significantly increased the depth permeation of CHG compared to the commercial benchmark (Hibiscrub®, containing 4% w/v CHG) (p < 0.05). The optimised formulation was further characterised using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), which indicated that the depth of dermal penetration achieved was sufficient to reach the skin strata that typically harbours pathogenic bacteria, which is currently inaccessible by commercial CHG formulations. This study therefore indicates that a G3 PAMAM-NH₂ dendrimer gel may be viable as a permeation enhancer of CHG, for improved skin antisepsis in those at risk of a skin or soft tissue infection as a result of surgical intervention.

Graphical abstract

Section snippets

1.Introduction

Chlorhexidine digluconate (CHG) is a cationic bisbiguanide which is typically used for skin antisepsis prior to surgery. The National Institute for Health and Care Excellence (NICE) guidelines for prevention and treatment of surgical site infections name an aqueous or alcohol based solution of chlorhexidine (CHX) as the first choice antiseptic in the UK [1]. This status may be attributed to its ability to effectively kill surface bacteria with minimal reports of resistance, low mammalian

Materials

G3 PAMAM-NH₂ dendrimer (20% w/v in methanol), 2-hydroxyethyl cellulose (HEC, molecular weight ~ 1300000), trimethylamine (25% w/v in water), HPLC grade methanol (>99.8%,), glacial acetic acid (>99/7%) and HPLC grade acetonitrile (>99.8%) were obtained from Sigma Aldrich. Chlorhexidine digluconate (CHG, 20% w/v in water) and sodium octane-1-sulfonate monohydrate (99+% crystalline) were obtained from Alfa Aesar. Ethanol absolute was obtained from VWR. Glycerol was purchased from Acros Organics.

Co-formulation of CHG and G3 PAMAM-NH₂ dendrimer

Prior to drug-dendrimer co-formulation, delivery of CHG from the gel formulation was optimised through the formulation of a series of gels. An ethanol-based gel was chosen as they are fast acting, economical and convenient to use [8], [40], [41]. In addition, gels apply to the skin smoothly, are aesthetically pleasing, and the ethanol smell is associated with cleanliness. Gels have also been shown to be preferred over other conventional topical formulations, such as creams [42] and ointments

Formulation optimisation and the effect of CHG-PAMAM dendrimer Co-formulation on the in vitro permeation of CHG – Tape stripping HPLC analysis

HPLC analysis of pooled tape strips following Franz-type diffusion cell experiments was performed in order to quantify the amount of CHG that has permeated into the SC of porcine skin tissue. The concentration of CHG per mg of SC material (µg/mg) recovered from pooled tape strips from each formulation following the 24 h Franz-type diffusion cell study is shown in Fig. 1. Delivery of CHG from the gel formulation was optimised by altering the concentration of gelling agent, HEC (Fig. 1A) and

4.Conclusion

In conclusion, this study effectively demonstrated the ability of a gel formulation containing 4% w/v CHG and 1 mM G3 PAMAM-NH2 dendrimer to enhance the depth permeation of CHG within porcine skin. Permeation from the optimised co-formulation was found to deliver CHG across the entirety of the dermis, without apparent permeation via specific routes, such as appendages. The permeation enhancement effect of the PAMAM dendrimer was attributed to a physical effect on the skin barrier as opposed to

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The authors would like to acknowledge Professor Steve Chapman for his assistance within this study.

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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Dendrimer-mediated permeation enhancement of chlorhexidine digluconate: Determination of in vitro skin permeability and visualisation of dermal distribution

Abstract

Graphical abstract

Section snippets

1.Introduction

Materials

Co-formulation of CHG and G3 PAMAM-NH2 dendrimer

Formulation optimisation and the effect of CHG-PAMAM dendrimer Co-formulation on the in vitro permeation of CHG – Tape stripping HPLC analysis

4.Conclusion

Declaration of Competing Interest

Acknowledgements

Infect. Dis. Clin. North Am.

Journal of Controlled Release

Int. J. Pharm.

Int. J. Pharm.

Fed. Eur. Biochem. Soc. Lett.

Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids

Int. J. Mass Spectrom.

Appl. Surf. Sci.

Int. J. Pharm.

Eur. J. Pharm. Sci.

Prog. Polym. Sci.

Curr. Opin. Chem. Biol.

Journal of Controlled Release

Int. J. Pharm.

J. Hosp. Infect.

Toxicol. Vitr.

Eur. J. Pharm. Biopharm.

Eur. J. Pharm. Biopharm.

Int. J. Pharm.

Int. J. Pharm.

Int. J. Pharm.

Journal of Controlled Release

Int. J. Pharm.

Biochim. Biophys. Acta - Biomembr.

Adv. Drug Deliv. Rev.

Adv. Drug Deliv. Rev.

Eur. J. Pharm. Biopharm.

J. Colloid Interface Sci.

Eur. J. Pharm. Biopharm.

J. Hosp. Infect.

Int. J. Pharm.

J. Dermatol. Sci.

Thermochimica Acta

Chlorhexidine

Reducing Surgical Site Infections: A Review

Rev. Obstet. Gynecol.

Effects of Daily Bathing with Chlorhexidine and Acquired Infection of Methicillin-Resistant Staphylococcus Aureus and Vancomycin-Resistant Enterococcus: A Meta-Analysis

J. Thorac. Dis.

Antibiotic Resistance Threats in the United States

Microbiome Dynamics of Human Epidermis Following Skin Barrier Disruption

Genome Biol.

The Microbiome Extends to Subepidermal Compartments of Normal Skin

Nat. Commun.

Penetration of Chlorhexidine into Human Skin

Antimicrob. Agents Chemother.

The 500 Dalton Rule for the Skin Penetration of Chemical Compounds and Drugs

Exp. Dermatol.

Co-formulation of CHG and G3 PAMAM-NH₂ dendrimer