Antiseptics and disinfectants
Define the terms antiseptic and disinfectant
An antiseptic is a substance applied to tissue to destroy microorganisms or prevent infection, for example when cleaning a wound or prior to an invasive procedure.
A disinfectant serves the same purpose but is applied to a non-living surface, for example a bench or countertop for the purpose of sanitisation.
Describe the pharmacology of commonly used antiseptics
| Alcohol | |
|---|---|
| Examples | Ethanol, isopropyl alcohol |
| Pharmaceutics | Typically 60-90% concentration May be pigmented or combined with another agent (e.g. chlorhexidine) |
| Time frame | Rapid onset |
| Mechanism | Diffuses across the cell membrane and denatures proteins in microorganisms |
| Spectrum | Broad spectrum antibacterial and antifungal Limited antiviral |
| Adverse effects | Irritant, dries out tissue |
| Chlorhexidine | |
|---|---|
| Pharmaceutics | May be pigmented or combined with another agent (e.g. alcohol or cetrimide) |
| Time frame | Delayed onset Remains active after application with ongoing antimicrobial effect, giving it a 'residual' or longer-lasting effect |
| Mechanism | It is a positively charged molecule that binds to the cell membrane and interferes with DNA replication It also enters cytoplasm and forms irreversible precipitates which destroy the cell |
| Spectrum | Broad spectrum antibacterial and antifungal Limited antiviral |
| Adverse effects | Hypersensitivity reaction, neurotoxic |
| Iodine | |
|---|---|
| Pharmaceutics | Brown liquid, often combined with povidone to enhance water solubility |
| Pharmacokinetics | Kills bacteria in 1min and spores in 15min No sustained effect |
| Mechanism | Diffuses into cell cytoplasm and oxidises various proteins and lipids |
| Spectrum | Broad spectrum antibacterial, antifungal and antiviral |
| Adverse effects | Hypersensitivty reaction, stains skin |