Chlorhexidine is a disinfectant and antiseptic that is used for skin disinfection before surgery and to sterilize surgical instruments. It may be used both to disinfect the skin of the patient and the hands of the healthcare providers. It is also used for cleaning wounds, preventing dental plaque, treating yeast infections of the mouth, and to keep urinary catheters from blocking. It is used as a liquid or powder.
Side effects may include skin irritation, teeth discoloration, and allergic reactions. May cause eye problems if direct contact occurs. Use in pregnancy appears to be safe. Chlorhexidine may come mixed in alcohol, water, or surfactant solution. It is effective against a range of microorganisms though does not inactivate spores.
Chlorhexidine came into medical use in the 1950s. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. Chlorhexidine is available over the counter. The wholesale cost in the developing world is about 2.20 to 4.10 USD per liter of 5% solution. In the United Kingdom this amount costs the NHS about £4.80.
Uses
Chlorhexidine is used in disinfectants (disinfection of the skin and hands), cosmetics (additive to creams, toothpaste, deodorants, and antiperspirants), and pharmaceutical products (preservative in eye drops, active substance in wound dressings and antiseptic mouthwashes).
In endodontics, chlorhexidine is used for root canal irrigation and as an intracanal dressing, but has been replaced by the use of sodium hypochlorite bleach in much of the developed world.
Antiseptic
There is tentative evidence that it is more effective than povidone-iodine.
Chlorhexidine is active against Gram-positive and Gram-negative organisms, facultative anaerobes, aerobes, and yeasts. It is particularly effective against Gram-positive bacteria (in concentrations ≥ 1 µg/l). Significantly higher concentrations (10 to more than 73 μg/ml) are required for Gram-negative bacteria and fungi. Chlorhexidine is ineffective against polioviruses and adenoviruses. The effectiveness against herpes viruses has not yet been established unequivocally.
Chlorhexidine, like other cation-active compounds, remains on the skin. It is frequently combined with alcohols (ethanol and isopropyl alcohol).
Dental use
Chlorhexidine is often used as an active ingredient in mouthwash designed to reduce dental plaque and oral bacteria. It has been shown to have an immediate bactericidal action and a prolonged bacteriostatic action due to adsorption onto the pellicle-coated enamel surface. If it is not deactivated, chlorhexidine lasts longer in the mouth than other mouthwashes, which is partly why it is sometimes preferred over other treatments for gingivitis. To treat periodontal pockets equal or greater than 5Â mm, chlorhexidine is also available in high concentration (36%) in a gelatin chip.
There are oral pathologic conditions in which the maintenance of oral hygiene with the twice-daily use with 0.12% chlorhexidine gluconate solution (in which a salt of chlorhexidine and gluconic acid has been dissolved) is recommended for healing and regeneration of the oral tissues. These conditions included gingivitis, periodontitis, dental traumas (such as subluxation), oral cysts, and after wisdom tooth extraction. The clinical efficacy of the application of chlorhexidine as a component of oral rinses is well documented by many clinical studies summarized by review articles.
Continued use of products containing chlorhexidine for long periods can cause stains on teeth, tongue, and gingiva, also on silicate and resin restorations; prolonged use can also reduce bitter and salty taste sensations â€" this latter symptom can be reversed by ceasing use of chlorhexidine. The brownish discoloration of teeth and tongue is due to the disintegration of bacterial membranes, leading to the denaturation of bacterial proteins. At the same time, disulfide functions are reduced to thiol functions that form dark complexes with iron(III) ions found in saliva.
Mouthwashes containing chlorhexidine which stain teeth less than the classic solution have been developed, many of which contain chelated zinc.
According to the prescribing information, chlorhexidine gluconate has not been proven to reduce subgingival calculus and in some studies actually increased deposits. When combined with xylitol, a synergistic effect has been observed to enhance efficacy.
Chlorhexidine's role in preventing tooth decay (dental caries) is controversial and "the clinical data are not convincing".
Chlorhexidine is neutralized by common toothpaste additives such as sodium lauryl sulfate and sodium monofluorophosphate. Although data are limited, to maximize effectiveness, it may be best to keep more than a 30-minute interval between brushing and using the mouthwash, ″cautiously close to 2 hours after brushing".
Topical
Nepal is the first country in the world to use chlorhexidine to treat the umbilical cord of newborn babies, and received a USAID Pioneers Prize for reducing the neonatal death rate. Chlorhexidine is very effective for poor countries like Nepal and its use is growing in the world for treating the umbilical cord. A 2015 Cochrane review has yielded high-quality evidence that within the community setting, chlorhexidine skin or cord care can reduce the incidence of omphalitis (inflammation of the umbilical cord) by 50% and also neonatal mortality by 12%. Chlorhexidine gluconate is used as a skin cleanser for surgical scrubs, a cleanser for skin wounds, for preoperative skin preparation and germicidal hand rinses. Chlorhexidine eye drops have been used as a treatment for eyes affected by Acanthamoeba keratitis.
Side effects
Chlorhexidine does not meet current European specifications for a hand disinfectant. Under the test conditions of the European Standard EN 1499, no significant difference in the efficacy was found between a 4% solution of chlorhexidine digluconate and soap. In the U.S., between 2007 and 2009, Hunter Holmes McGuire Veterans Administration Medical Center conducted a cluster-randomized trial and concluded that daily bathing of patients in intensive care units with washcloths saturated with chlorhexidine gluconate reduced the risk of hospital-acquired infections.
Mechanism of action
At physiologic pH, chlorhexidine salts dissociate and release the positively charged chlorhexidine cation. The bactericidal effect is a result of the binding of this cationic molecule to negatively charged bacterial cell walls. At low concentrations of chlorhexidine, this results in a bacteriostatic effect; at high concentrations, membrane disruption results in cell death.
Chemistry
It is a cationic polybiguanide (bisbiguanide). It is used primarily as its salts (e.g., the dihydrochloride, diacetate, and digluconate).
Deactivation
Chlorhexidine is deactivated by forming insoluble salts with anionic compounds, including the anionic surfactants commonly used as detergents in toothpastes and mouthwashes, anionic thickeners such as carbomer, and anionic emulsifiers such as acrylates/C10-30 alkyl acrylate crosspolymer, among many others. For this reason, chlorhexidine mouth rinses should be used at least 30 minutes after other dental products. For best effectiveness, food, drink, smoking, and mouth rinses should be avoided for at least one hour after use. Many topical skin products, cleansers, and hand sanitizers should also be avoided to prevent deactivation when chlorhexidine (a topical itself or the residue from a cleanser) is meant to remain on the skin.
Synthesis
The structure is based on two molecules of proguanil, linked with a hexamethylenediamine spacer.
Brand names
Betasept, ChloraPrep, Chlorostat, Avagard, BactoShield CHG, Corsodyl, Dyna-Hex, Hibiclens, Hibistat, Operand Chlorhexidine Gluconate, Peridex, PerioChip, PerioGard
Veterinary medicine
For use in animals, chlorhexidine is used as a topical disinfectant of wounds. It is also more beneficial to wound healing than using saline solutions alone. Post-surgical respiratory problems have been associated with the use of chlorhexidine products in cats. If the product is put into the ear in the presence of a ruptured eardrum, it can also lead to deafness. It is commonly used to manage skin infections in dogs. In addition to this, it is an active ingredient in disinfectant products used within the dairy farming industry.
See also
- Polyaminopropyl biguanide
- Polyhexanide
- Triclosan
References
External links
- FDA Professional Drug Information