Ultra Violet Light Disinfection in Pharmaceuticals

Ultraviolet light is used as a disinfection agent in pharmaceuticals. Short wavelengths of ultraviolet light create a harmful effect on microorganisms by destroying their nucleic acids and prevent the growth of the microbial cells.

First of all ultraviolet light is used for water disinfection is the United States in 1916. Now a day it is widely used to disinfect the drinking water and wastewater.  This is a low cost and very effective disinfection process.

Ultraviolet light is short wavelength light than visible light having electromagnetic radiations. At a specific wavelength of 2537⁰A or 256 nm is harmful to microorganisms and destroys the DNA of microbial cells. Thymine base of DNA and RNA is reactive with the ultraviolet radiations and forms dimers (T=T). 

These dimers inhibit the replication of DNA and RNA. Due to this microorganism cannot grow and will unable to increase in number. This effect can be reversed in the presence of light termed as photoreactivation. So the dose of ultraviolet light should be too enough to damage the thymine beyond the repair. The effectiveness of ultraviolet radiation is more than 99.99%.

Disinfection of the microorganisms is directly depending upon the quantity of energy or UV dose absorbed by the microorganism. Disinfection by UV follows the first order kinetic reaction. The microbial kill rate is directly proportional to the dose of ultraviolet light applied. Higher the dose applied, higher will be the kill rate. The intensity of ultraviolet rays of UV tube decreases with the time of use so it is recommended to use a UV tube only 6000 burning hours. As per cGMP, it is recommended to use a digital hour meter where ever UV tube is used for ultraviolet radiation to count the burning hours.

Microorganisms	Dose in Microwatt-Second/cm2
Bacillus subtilis	11000
Clostridium	22000
E.coli	6600
Pseudomonas aeruginosa	10500
Salmonella sp.	10000
Aspergillus niger	330000
Candida albicans	13200

UV is used in a lot of places for disinfection but the following are the applications in pharmaceuticals.

1. Ultra Violet Light Disinfection in Purified Water System: It is very useful in purified water system disinfection. UV light is fitted in the return loop of purified water distribution system. It helps to prevent the entrance of the microorganisms into the water storage tank from the distribution system and also remove the microbial contaminants from the purified water distribution system by preventing the formation of biofilm.

Related: Chemical Sanitization of RO Systems and Biofilm Removal

2. Ultra Violet Light Disinfection in Wastewater Treatment System: It helps to remove the microbial load from the treated wastewater in the effluent treatment plant. Treated effluent is passed through the UV tube and the microorganisms including the pathogens or generated in a septic tank are killed effectively.

Related: Waste Water Treatment Process

3. Ultra Violet Light Disinfection in Laminar Air Flow Unit: LAF is known a class 100 area which is used for microbial analysis in pharmaceuticals. Maintenance of a class 100 area is not an easy task so UV lights help in this regard. Burning of ultraviolet light before the microbial analysis can remove all retained microorganisms in LAF unit.

Related: SOP for Laminar Air Flow Workbench

4. Ultra Violet Light Disinfection in Pass Box: Pass boxes are used to transfer the material across the two different classified classes. ultraviolet light is installed in all pass boxes to minimize the entrance of microbial contaminants ion sterile area.

Also see: Removal of Pathogens from Water Systems