Ultra Violet Light – Role & Application in Pharmaceuticals


Ultraviolet  light (UV) is electromagnetic non ionizing radiation and under wavelength (240-280 nm) use as a effective anticepticize or disinfection for the killing of all microorganisms. UV act as a mutagen which cause mutation in DNA during exposure of a cell.In pharma UV use for many purpose like purification of water, in biosafety cabinet,in pass boxes and in waste water treatment.


Mode of Action:

When microorganisms are subjected to UV light, cellular DNA absorbs the energy by purines and pyrimidine bases, and adjacent thymine molecules link together, as figure illustrates. Linked thymine molecules are unable to encode adenine on messenger RNA molecules during the process of protein synthesis. Moreover, replication of the chromosome in binary fission is impaired. The damaged organism can no longer produce critical proteins or reproduce, and it quickly dies. Ultraviolet light is especially effective in inactivating viruses. However, it kills far fewer bacteria than one might expect because of DNA repair mechanisms. Once DNA is repaired, new molecules of RNA and protein can be synthesized to replace the damaged molecules.

So the dose of ultra violet light should be too enough to damage the thymine beyond the repair. The effectiveness of ultra violet radiation is more than 99.99%.

Ultra violet light is short wavelength light than visible light having electromagnetic radiations. At a specific wavelength of 2537⁰A or 256 nm is harmful microorganisms and destroys the DNA of microbial cells.


Effectiveness of UV :

  • Depend on a length of exposure time express in second.
  • The Intensity and Wavelength of UV express in milli watt per square centimeter (mW/cm2)
  • The presence of particles that can protect the microorganism.
  • Potency of Microorganism to withstand UV during its exposure.
  • Water should not be turbid as turbidity hinder the UV light to pass.

Application of UV in pharma industry :

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

In pharmaceuticals, Ultra violet light is used as a disinfection agent. Ultra Violet light is used for disinfection of purified water, treated effluent and pass boxes. Ultra violet light disinfection is also used in LAF unit.

Short wavelengths of ultraviolet light create harmful effect on microorganisms by destroying their nucleic acids and prevent the growth of the microbial cells.

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 ultra violet light applied. Higher the dose applied, higher will be the kill rate. Intensity of ultra violet rays of UV tube decreases with the time of use so it is recommended to use a UV tube only 6000 burn hours. As per cGMP, it is recommended to use a digital hour meter where ever UV tube is used for ultra violet 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

1.0 Ultra Violet Light Disinfection in Purified Water System


UV disinfection is major technique use in treatment of water. It is very useful in purified water system disinfection. UV light is fitted in the return loop purified water distribution system. When water pass through UV tube it show its germicidal effect. It helps to prevent the entrance of the microorganisms into the water storage tank from the distribution system and remove the microbial contaminants from the purified water distribution system by preventing the formation of biofilm. UV  inhibit growth chlorine resistant microorganism such as Cryptosporidium and Giardia.

2.0 Ultra Violet Light Disinfection in Treatment of Effluent water


To reduce biobuden of environment all waste water treated with UV before relasing to reduce the amount of microorganisms. It helps to remove the microbial load from the treated waste water in the effluent treatment plant. Treated effluent is passed through the UV tube and the microorganisms including the pathogens or generated in septic tank are killed effectively.

3.0 Ultra Violet Light Disinfection in Biosafety Cabinet

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 helps in this regard.


UV plays a key role in laminar air flow by killing bioburden and provide sterile area.UV light is locate inside the laminar and it uses before and after the work.

Burning of ultra violet light before the microbial analysis can remove all retained microorganisms in LAF unit.

3.0 Ultra Violet Light Disinfection in pass box and inside all sterile area :


Pass boxes are used to transfer the material across the two different classified classes.  UV light is installed in all pass boxes to minimize the entrance of microbial contaminants in sterile area. Ultra violet light  is also locate inside all entry rooms and exit rooms of sterile area where it works through decontaminate the passing air.