Sterilization in Pharmaceuticals


Definition: Sterilization is the procedure of complete destruction (Killing) of all microorganisms present in a system. A product free from living microorganisms is called a “sterile product”.

  • Antiseptic: Antiseptic substance stops the growth of microorganisms by preventing their action without destroying them is called antiseptic.
  • Bactericide: The substance that kills bacteria is named as “Bactericide”.
  • Bacteriostatic: Bacteriostatic refers to a chemical that stops or slows bacterial growth.
  • Disinfection: A procedure that removes the infection likely by destroying microorganisms but not usually bacterial spores.
  • Germicide: A material, but not necessarily bacterial spores, that kills harmful germs.
  • Viricide: It is a substance that kills viruses.
  • Sterility: The absence of viable microorganism is called ‘sterility’ & preparation free from viable microorganisms are called ‘sterile’.


  • The microorganism show variable resistance to different Methods.
  1. Thermal death time: It can be described as the length of time needed to eradicate a certain type of microbe under particular circumstances and at a specified temperature.
  2. Death rate of microorganisms: There is no direct technique to determine when the sterility will be completed.
  3. Decimal reduction time (D value): It is defined as the time in min. required to decrease the number of the viable organisms by 90%.
  • The order of death of microorganisms can be calculated from equation:

K = 1/t (log No.— log N)


  • K stands for constant which depends on organism, temperature and medium.
  • t is time of exposure in min.
  • No stands for number of organisms viable at the beginning of a time interval.
  • N=Number of organisms still viable at the end of the period.

K= 1/t

  • As, it is after 90% reduction in microorganism.
  • The D value, often known as the decimal reduction time, is defined as time t.

D= 1/K


  • Physical Methods
    1. Dry Heat Sterilization
    2. Moist Heat Sterilization
    3. Radiation Sterilization
      1. Use Of Ultra Violet Rays
      2. Ionising radiation
  • Chemical Methods:
    • Sterilization by heating with bactericide.
    • Gaseous Sterilization.
  • Mechanical Methods: It includes the filtration of parenteral preparation through the following bacteria proof filters:
    • 1. Ceramic filters
    • 2. Seitz filter
    • 3. Sintered glass filters
    • 4. Sintered metal filters
    • 5. Membrane filters
Sterilization in Pharmaceuticals
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