Granulation and particle sizing

ABSTRACT : The work describes the manufacturing of granules which are considered as a best form to manufacture tablets. At the end of the process granules of different particle sizes are obtained but the granules which are above the 125µm and below 500µm are accepted for tabletting. The rest of the granules are discarded as they are considered unsuitable for production as well as its bioavailability after administration.


Granules are irregular particles of which the particular particle size can be determined by sieve shaking using various sized sieves. Drugs that are to be tabletted should be granulated before punching as most of the drugs require excipients for proper punching. There are three processes by which a drug can be granulated. They are 1. Wet granulation, which involves the use of binder solution and the cake formed is wet, 2. Dry granulation, where the cake formed is dry and is compressed, 3. Direct compression, which is rarely under use and the drug is directly compressed using diluents like spray dried lactose.


Step:A Paracetamol(maindrug),lactose(diluent),sodium starch glycollate(disintegrate)were weighed and mixed in a planetary mixer whilst adding binder solution (PVP solution) until the mass became a puffy pastry rather than a doughy or dry mixture. The consistency of the cake formed was significant as the granules of acceptable size were achieved when the mass was consistent.

Step: B The cake was passed throw an oscillating granulator where the wet granules were collected onto a metal tray. The tray was kept in a hot air oven at 70°C and dried until there was no further loss of moisture from the granules.The moisture content can be determined instantaneously using moisture determining instrument which readily gives the amount of moisture present in the granules.

Step: B The dried granules were weighed and on order to separate granules of different sizes, sieve shaker was utilized and the mesh size varies from 1000µm to 45µm. The granules that were collected above the sieve of size 125µm to 500µm were collected and used for the further processing which is punching of granules into tablets.The excipients used while granulating help in easy formation of granules and also help in enhancing the activity of the drug after administration.

IDEAL PROPERTIES OF EXCIPIENTS: Excipients improve patient compliance and functioning of the drug.

  • Be inert
  • Produce no therapeutic effect
  • not modify the action of the drug
  • not effect bioavailability of drug


The granulation technique concludes that in order to get a better flow property uniform particle size is necessary. The mode value obtained indicates that the granules were mostly of the size 129.44 µm. Dose accuracy is primarily dependant on particle size and is most essential requirement in the field of pharmaceuticals. Hence it is important to obtain granules of uniform size.


  1. Aulton, M.E. (2002). Pharmaceutics: The science of dosage form. 2nd Ed. London: Churchill Livingstone, pp 153-154, 364-365.
  2. V.N.P. Le, P. Leterme, A. Gayot and M.P. Flament, Journal of Pharmaceutics, Volume 321. Issues 1-2, 14 September 2006, Pages 72-77.
  3. British Pharmacopeia, Appendix XVII (2009), Sieves and filters

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