Alcohol and Antiseptics

Ethanol

• Ethanol is utilized to clean skin before immunization and venipuncture.
• It disrupts lipid structures in membranes and denatures proteins.
• Optimal efficacy is achieved with 70% ethanol; 100% ethanol is less effective.
• Often employed as an antiseptic, especially prior to venipuncture.
• Not as effective as iodine compounds for blood cultures and intravenous catheter placements.
• Ethanol does not kill bacterial spores, making it unsuitable for sterilization.

Detergents

• Composed of a hydrophobic lipid-soluble portion and a polar hydrophilic group.
• Disrupt cellular membranes by interacting with lipids and surrounding water.
• Quaternary ammonium compounds, like benzalkonium chloride, are common cationic detergents used for skin antisepsis.
• Benzalkonium chloride is found in Lysol, a popular disinfectant for surfaces.

Phenols

• Phenol was historically the first disinfectant used in operating rooms but is rarely utilized now due to causticity.
• Chlorhexidine, a chlorinated phenol, is widely used for surgical hand disinfectants and wound cleaning.
• Hexachlorophene, a biphenol, was used in germicidal soaps but is restricted due to neurotoxicity concerns.
• Phenols damage membranes and denature proteins.

Chlorine

• Utilized as a disinfectant for water purification and swimming pool treatment.
• The active component in bleach (hypochlorite, Clorox) for home and hospital disinfection.
• Acts as a potent oxidizing agent, killing microbes by cross-linking essential sulfhydryl groups in enzymes.

Iodine

• Iodine is the most effective skin antiseptic in medical practice, crucial for blood cultures and IV catheter insertion to prevent contamination.
• Functions as an oxidant that inactivates sulfhydryl-containing enzymes and binds to tyrosine residues in proteins.
• Comes in two forms:
  • Tincture of iodine (2% solution in ethanol) prepares the skin but can irritate, necessitating removal with alcohol.
  • Iodophors, which are iodine-detergent complexes, are less irritating and used for skin preparation before surgeries.
• Povidone-iodine is a widely used iodophor in antiseptic applications.