Chlorhexidine: A Multi-Functional Antimicrobial Drug

Chlorhexidine gluconate is an effective bactericidal agent and broad-spectrum antimicrobial drug. It has been extensively researched and is the “gold standard” antimicrobial in oral hygiene. Chlorhexidine is useful in many clinical disciplines including periodontics, endodontics, oral surgery and operative dentistry. Introduction Chlorhexidine gluconate (chlorhexidine) is a broad-spectrum antimicrobial drug. Acting as an antiseptic, it is an effective bactericidal agent against all categories of microbes, including bacteria, yeast, and viruses. Chlorhexidine molecules are positively charged (cations) and most bacteria and surface structures in the oral cavity, including the surfaces of teeth and mucous membranes, are negatively charged (anions). In accordance with the principle that opposite charges attract, chlorhexidine binds strongly to all these surface structures. When chlorhexidine binds to microbial cell walls it induces changes, damaging the surface structure, leading to an osmotic imbalance with consequent precipitation of cytoplasm causing cell death. The substantivity of chlorhexidine enhances this bactericidal effect, which allows for the retention of chlorhexidine in the oral cavity and a prolonged residual antimicrobial effect for up to 12 hours or longer depending on the dosage and form. Chlorhexidine is safe and has an inherent advantage over antibiotics by not producing resistant microorganisms. As a result chlorhexidine can be used repeatedly and over long periods of time. Furthermore, it destroys all categories of microbes, not just bacteria, and there is little risk for the development of opportunistic infections. As with many FDA approved drugs, the use of chlorhexidine does have known disadvantages; however, these disadvantages are a small trade off compared to the many advantages and are reversible once the use of chlorhexidine is discontinued. Chlorhexidine was first used as a mouthrinse as an adjunct to conventional non-surgical periodontal therapy in Europe in the early 1970s. It received FDA approval in 1986 under the brand name PERIDEX® (Zila Pharmaceuticals) based on studies showing that it reduced gingivitis by up to 41%. Soon after,1 PERIDEX®‚ was the first mouthrinse to receive the ADA Seal of Acceptance. Generic rinses have been available since 1994 and are available from many different companies. In order to qualify as a generic, the medication must prove to have 80–120% of the bioavailability of the name brand to be considered bioequivalent. To date, there have been no published equivalency studies between the brand PERIDEX® and any generic rinses. Chlorhexidine has proven efficacy as a broad-spectrum antimicrobial for reducing supragingival plaque. In 1997, chlorhexidine was introduced in a locally applied, controlled-release gelatin chip (PerioChip®, OMNII Oral Pharmaceuticals) as a treatment to reduce pocket depths in patients with adult periodontitis. Since then there have been many off-label uses arising from the desire to effectively reduce microbial pathogens to enhance treatment results. Some of the uses will be reviewed so that clinicians can make an informed decision about incorporating chlorhexidine into their treatment protocols. Figure 1. When the chlorhexidine molecules adhere to and damage the surface of bacteria, osmotic imbalance and the precipitation of cytoplasm ensue and result in cell death.