Antiseptics: Definition, Mechanism, Common Agents, and Clinical Uses
Antiseptic vs. Disinfectant vs. Antibiotic
- Antiseptic: Applied to living tissue (skin, mucosa) to reduce microbial load.
- Disinfectant: Applied to inanimate surfaces (instruments, counters).
- Antibiotic: Systemic or topical agent that inhibits/kills bacteria inside the body.
Common Antiseptics
| Agent | Mechanism | Typical Use | Cautions |
|---|---|---|---|
| Alcohols (60–90% Ethanol/Isopropanol) | Protein denaturation, membrane disruption | Skin prep, hand rub | Flammable, drying, ineffective on spores |
| Chlorhexidine Gluconate (2–4%) | Membrane disruption, residual activity | Surgical prep, central line insertion, oral rinse | Ototoxic if enters middle ear; corneal damage; neutralized by soap |
| Povidone-Iodine (10% PVP-I) | Free iodine oxidizes proteins/nucleic acids | Broad skin prep, mucosal (dilute) | Inactivated by organic matter; thyroid dysfunction risk (neonates, pregnancy); allergy |
| Hydrogen Peroxide (3%) | Oxidative damage via free radicals | Wound irrigation (controversial—cytotoxic) | Impairs fibroblast; not for deep wounds |
| Benzalkonium Chloride | Membrane disruption | Wound cleanser, hand sanitizer (less effective vs. alcohol) | Less reliable vs. norovirus, mycobacteria |
Selection Principles
- Site (mucosa vs. skin), patient age, allergies, procedure invasiveness, organism spectrum.
- Follow contact time guidelines (e.g., CHG 2 min, alcohol until dry).
- Avoid combinations that inactivate (e.g., CHG + soap).
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