Mode of Action of Disinfectant Solutions

A lot of disinfectants are used for sanitization and disinfection in pharmaceutical industries. These have different antimicrobial properties based on their mode of action. Disinfectants having a different mode of actions are helpful to prevent the development of the resistance in microbes.

Mode of Action of Different Disinfectants:

1. Aldehydes: Aldehydes have antibacterial, antifungal, antiviral and sporicidal activity. These are helpful to destroy the spores of Bacillus subtilis and Clostridium sporogenes. Glutaraldehyde and formaldehyde are commonly used aldehydes in disinfectants. 2% solution inhibits the activity of the enzyme in the cell, denature the cell proteins.

Example: Glutarex contains glutaraldehyde.

2. Alcohols: All types of alcohols are antiseptic and antiviral agents. These are highly effective in combination with water. These are effective against Poliovirus and Rhinovirus. 70 % solutions of Ethyl alcohol and Isopropyl alcohol are commonly used as hand disinfectants in pharmaceuticals. Alcohol denatures the cell wall proteins.

Example: Triclogel contains 75% ethanol.

3. Chlorine and Sodium Hypochlorite: Chlorine or Sodium Hypochlorite is generally used in water disinfection. This is a sporicidal agent and acts against the spores forming bacteria. It is an oxidizing agent and reacts with the enzymes of the cell.

4. Phenols: Chlorocresol and Chloroxylenol are used as disinfectants. These are general disinfectants and also have antifungal and antiviral properties. It denatures the proteins and enzymes of the cells.

Example: Dettol contains Chloroxylenol and Lysol contains p-Chloro-o-benzylphenol.

5. Hydrogen Peroxide (H₂O₂): It is also an oxidizing agent that reacts with the proteins and DNA of the cell. A 5% solution in water is effective against the bacteria and fungus. it is very effective in water system sanitation. High concentrations (10-30%) are effective against bacterial spores and viruses. It acts as oxidant and attracts on essential cell components as DNA, lipids and proteins.

Example: Gramicid contains Hydrogen peroxide and Silver compound.

6. Benzalkonium Chloride: A 0.0002% solution is effective against the vegetative cells. It increases the permeability of the cell membrane and causes the coagulation of cell contents.

7. Chlorhexidine Gluconate: It is a general antiseptic. A 0.5% solution kills the all bacterial vegetative cells. It destroys the cell content by coagulation.

Example: Savlon contains Chlorhexidine gluconate and cetrimide.

Disinfectants used for sanitation and cleaning in pharmaceutical industries must be selected on the basis of their mechanism of action. Disinfectants having same mechanism may lead to develop the resistance in microbes. 

Therefore, the disinfectants should have difference in their mode of action. For example if you have to select three disinfectants then the combination may be - one containing Aldehyde, one containing Hydrogen Peroxide and other should contain Benzalkonium Chloride.