Surface chlorhexidine

Silver sulfadiazine is present on the external CVC surface chlorhexidine on the intraluminal CVC surface The antibiotics, present both onto the external and the internal CVC surface, are to the catheter surface through a TDMAC coating Drugs are adsorbed onto both catheter surfaces Sold under the trade name AMC Thromboshield , this catheter has the two bioactive agents onto both the internal and the external surfaces... 

Topical antiseptics and germicides are primarily used to reduce the number of bacteria on skin surfaces. Some of these drag s, such as chlorhexidine gluconate, may be used as a surgical scrub, as a preoperative skin cleanser, for washing the hands before and after caring for patients, and in the home to cleanse the skin. Others may be applied to minor cuts and abrasions to prevent infection. Some of these drag s may also be used on mucous membranes. 

Quaternary ammonium compounds (QACs Chapter 10) such as cetrimide, and also the bisbiguanide, chlorhexidine, are notoriously prone to promote clumping. A non-ionic surface-active agent of the type formed by condensing ethylene oxide with a long-chain fatty acid such as Cirrasol ALN-WF (ICI Ltd), formerly known as Lubrol W, together with lecithin, added to the diluting fluid has been used to overcome this effect. 

Surface disinfectants Compounds containing phenolics, chlorhexidine (not effective against bacteria spores), quaternary ammonium salts (additional activity if bis-n-tributyltin oxide present), hypochlorites such as household bleach, alcohols such as 70-95% ethanol and isopropyl (not effective against bacteria spores), potassium peroxymonosulfate, hydrogen peroxide, iodine/iodophores, and triclosan. 

Chlorhexidtne is a symmetrical cationic molecule that is most stable as a salt the highly water-soluble digluconate is the most commonly used preparation. Because of its cationic properties, it binds strongly to hydroxyapatite (the mineral component of tooth enamel), the organic pellicle on the tooth surface, salivary proteins, and bacteria. Much of the chlorhexidine binding in the mouth occurs on the mucous membranes, such as the alveolar and gingival mucosa, from which sites it is slowly released in active form. 

Although chlorhexidine affects virtually all bacteria, gram-positive bacteria are more susceptible than are gram-negative organisms. Furthermore, Streptococcus mutans and Antinomies viscosus seem to be particularly sensitive. S. mutans has been associated with the formation of carious lesions in fissures and on interproximal tooth surfaces and has been identified in large numbers in plaque and saliva samples of subjects with high caries activity. 

The most conspicuous side effect of chlorhexidine is the development of a yellow to brownish extrinsic stain on the teeth and soft tissues of some patients. The discoloration on tooth surfaces is extremely tenacious, and a professional tooth cleaning using abrasives is necessary to remove it completely. The staining is dose dependent, and variation in severity is pronounced between individuals. This side effect is attributed to the cationic na-... 

In vitro, chlorhexidine can adversely affect gingival fibroblast attachment to root surfaces. Furthermore, protein production in human gingival fibroblasts is reduced at chlorhexidine concentrations that would not affect cell proliferation. Such findings corroborate earlier studies showing delayed wound healing in standardized mucosal wounds after rinsing with 0.5% chlorhexidine solution. 

Chlorhexidine is a strong base (Lewis acid-base theory) because it reacts with acids to form salts of the RX2 type, and it is practically insoluble in water (<0.008% wt/vol at 20°C). The water solubility of the different salts varies widely as demonstrated in Table 2.13. Chlorhexidine is moderately surface-active (a net+chare over its surface) and forms micelles (molecular aggregates form colloidal particles) in solution the critical micellar concentration of the acetate is 0.01% wt/vol at 25°C (Heard and Ashworth 1969). Aqueous solutions of chlorhexidine are most stable within the pH range of 5-8, and above pH 8.0 chlorhexidine is precipitated because conditions for a base (>pH 7) reaction are present. 

Fig. 2.66 The mechanism of antibacterial activity of chlorhexidine diacetate on a bacteria cell (a) Natural cell with surrounding negative surface charge (gray), (b) introduction of chlorhexidine diacetate, pH <7, surrounding positive charge (red) and (c) disruption of cell membrane...

Phenols Disrupt cell membranes, denature proteins, and inactivate enzymes phenol is not impaired by organic matter Phenol is used to disinfect surfaces and destroy cultures amylphenol destroys vegetative organisms and inactivates viruses on skin and objects chlorhexidine gluconate is effective as surgical scrub... 

It is unclear how growth was actually monitored because QACs are well known to react with the constituents of culture media to produce a dense opalescence or turbidity. Be that as it may, it was also found that resistant and sensitive cells exhibited different surface properties, with the former possessing an increased lipid content. As found by other workers using chlorhexidine, chloroxylenol and other QACs [173, 174], resistance was unstable being lost when the resistant cells were grown in biocide-free media. 

Surface-Chemical Aspects of Chlorhexidine in Plaque Control... 

Other studies have shown appropriate concentrations of chlorhexidine to inhibit adenosine triphosphatase of Streptococcus faecalis membrane. Electron micrographs have shown a so-called blistering of bacterial cell walls (42) by chlorhexidine. This was attributed to cellular extrusion or to the accumulation of drug aggregates on the cell surface (43). 

A detailed study of chlorhexidine s surface-chemical characteristics was undertaken in our laboratories. This included work with a series of carefully selected analogs comprising segments of the parent molecule (Structure II R = n-hexyl, n-propyl, or H) or extensions of these (Structure II R = n-octyl or n-dodecyl). 

El-Falaha BMA, Rogers DT, Furr JR, Russell AD. Surface changes in Pseudomonas aeruginosa exposed to chlorhexidine diacetate and benzalkonium chloride. Int J Pharm 1985 23 239—243. 

The aqueous concentration of chlorhexidine normally recommended for contact with mucous surfaces is 0.05% w/v. At this concentration, there is no irritant effect on soft tissues, nor is healing delayed. The gluconate salt (1% w/v) is frequently used in creams, lotions, and disinfectant solutions. 

Addy M, Moran J, Griffiths AA, Wills-Wood NJ. Extrinsic tooth discoloration by metals and chlorhexidine I surface protein denaturation or dietary precipitation Br Dent ] 1985 159 281-285. 

Some ingredients of eye medications may increase the permeability of the cornea. Surface-active agents are knovm to interact with membranes to increase the permeability benzalkonium chloride has surfactant properties and may well have some effect on comeal permeability, although its primary purpose is as a bacteriostat and bactericide. Chlorhexidine acetate and cetrimide, both of which are surface-active, are also used. 

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