Pellets
Pellets can be defined as small, free flowing,spherical -particulates manufactured by the
agglomeration of fine powders or granules of drug substances and excipients using
appropriate processing equipment.
Properties of pellets:-
●Uncoated Pellets:- They have high physical strength with uniform shaped pellets along with
improved flow properties with an optimum size range of 600 and 1000 micrometer provided
with good hardness and low friability.
●Coated Pellets:- Along with uncoated properties of pellets ,coated pellets maintains the
active ingredients to give the uniform size of final dosage form within its standard limits, and
also give desirable drug release studies.
Advantages of pellets:-
●It enhances the drug absorption.
●Due to even distribution of ingredients there are no chances of harmful effects.
●A pellet carry high drug benefit in low sized particles , the side effects are usually zero to
none.
●By coating we can produce controlled release tablets .
●Improves aesthetic appearance of drug.
Disadvantages of pellets :-
●Requires highly specialised equipments .
●Filling into gelatin capsule is difficult.
●Requires trained personnel.
●More complicated in formulation of multiple unit dosage form.
● Formation of pellets is a time consuming process .
Formulations required for pellets:-
●Fillers:- They are used to add bulk to products and make very small active components
easy for consumer to take
●Binders:-They are added to bind powder make pellet integrity.
●Lubricants:-They are added to reduce friction between particles and surface of equpments.
●Seperating agent:-Seperating agents promote separation of pellets into units .
●Surfactants:-Surfactants are added to liquid to improve wettability by lowering interfacial
tension between the liquid and drug particles .
PELLETIZATION:-
It can be defined as the agglomeration process that convert fibre particles or particles or
particles of bulk drugs and excipients into small,free flowing,more or le spherical unit, called
pellets.
DIFFERENT TECHNIQUES OF PELLETIZATION:-
1 Layering technique:-Layering process is the most convenient technique of pelletization.In
this process successive layer of drugs are coated onto a nuclei , which may be the granule of
same material or inert stater seed .It is classifies into two sub categories :
a)Powder layering strategy: in this technique ,the nuclei is initially sprayed with binder
solution after which the powder is added . Theses nuclei are subjected to rotation in pan
where they get coated with powder particles , thereby forming layers of coating material by
adhesive forces.Capillary forces developed in liquid phase help in adhesion of these particles
to the nuclei.Successive spraying is done until desirable size of pellet is obtained.
b)Solution/Suspension layer: in this technique the drug particles and other ingredient are
dissolved in suitable solvent .this solution or suspension is then coated evenly on the nuclei
by spraying .This is followed by drying process The dissolved material crystallizes to form
solid bridge between the inner core material and the spray coated particles .The procedure is
continued until the suitable layer of drug is coated on the inner core nuclei.
2 Cryopelletization:- in cryopelletization liquid nitrogen is used as solidifying medium.In
this process the drug solute/suspension in a suitable solvent is exposed to an atmosphere of
liquid nitrogen at -196 C .Rapid heat transfer between the drug solution and liquid nitrogen
will permit the material to freeze .The volume of nitrogen needed for preparing the pellets
depend upon temperature and solid ingredients of the suspension/ solution being handled.The
instrument through comprised of a perforated plate through which drug suspension is passes
and introduced into atmosphere of liquid nitrogen below .The leads to instantaneous freezing
of particles .The frozen pellets are thn stored at -600 C before drying.
3 Extrusion Spheronization:- Extrusion spheronization is a granulation process which
produces dense pellets of high sphericity and have narrow size distribution .
This method is useful for producing granules with improved drug loading without forming
excessively large particles . This can also be utilized for obtaining oral controlled release
dosage form with consumption of less excipients .
4 Spray drying and congealing:-The drug suspension/solution is atomized into fine droplets
with or without the addition of excipients , which is exposed radially to a moving steam of
hot gas .The temperature of droplets is immediately increased and fine droplets get dried,
forming spherical particles.
5 Balling:- Balling also known as agglomeration is a technique in which physical mixtures of
drug and excipients are converted into spherical pellets by constant tumbling or rolling
motion. Balling can be categorised into 2 types:liquid induced agglomeration and melt
induced agglomeration .Balling is popularly used in fertilizer or iron ore industries ,while its
pharmaceutical applications are limited .In liquid induced agglomeration ,liquid is
introduced into the powder during or before the agitation step.Agglomerates or nuclei are
formed when powder comes in contact with the liquid phase . Melt induced agglomeration is
similar to that of liquid induced agglomeration except that here the binding material is a melt.
EQUIPMENTS USED IN MANUFACTURING OF PELLETS:-
1 Extruder: It helps in extrusion.Extrusion is a process of converting raw material into
uniform shape and density by forcing it through a die under controlled conditions.
Single Screw Extruder
Twin Screw Extruder
2 Spheronizer: it helps in spheronization to form uniform size spherical particles.
3 Fluidized bed granulator: it helps in granulation .
4 Spray drier: A drug solution or suspension is sprayed without excipients,into hot air
stream, generating dry and highly spherical particles.
5 Spray congealing: Also called spray chilling a technique similar to spray drying ,but no
heat source required.
Patents
1 Patent no: CA241580C
Title: Pharmaceutical pellets comprising tamsulosin.
Abstract: The invention relates to coated tamsulosin pellets and to unit dosage forms made
therefrom.The invention provides a pharmaceutical dosage form comprising a plurality of
pellets , wherein each pellets comprises a pellet core having a diameter within the range of
0.3-0.9 mm comprising a tamsulosin hydrochloride, microcrystalline cellulose ,a
pharmaceutically acceptable water permeable acrylic polymer and water .
Inventor: Johannes Jan Platteeuw
Current Assignee: Synthon BV
Year of patent: 2003
2 Patent no: US6290990B1
Title: Slow release matrix pellets.
Abstract: Slow release matrix pellets with spherical or lenticular shape nd uniform
maximum diameter in the range from 0.5 to 4mm, 0.1-87 percent by weight of at least one
biologically active compound.5-50 percent by weight of at least one water-insoluble polymer.
Inventor: Sven Grabowski,Joerg Rosenberg,Axel Sanner
Current Assignee: BASF SE
Year of patent: 2001
3 Patent no: EP3413875B1
Title: Cholestyramine pellets
Abstract: The invention relates to small cholestyramine pellets that can be prepared by
extrusion .The pellets have a high cholestyramine loading and are stable enough to be coated
with one more coating layers.
Inventor: Per-Goran Gillberg, Nils Ove Gustafsson,Nils Olof Lindberg,Jessica Elverson
Current Assignee: Albireo AB
Year of patent: 2017
4 Patent no: WO1993007859A1
Title: Novel pharmaceutical pellets
Abstract: Drug loaded pellets are produced through melt spheronization in which the active
pharmaceutical is blended with various excipients and binders. The formulation is fed to an
extruder where it is heated and extruded at a speed of approximately 0.05 to 10mm/sec at
60-180C.The extrudate is then cut into pieces in a pelletizer and subsequently fed to a
spheronizer for uniform pellet formulation.
Inventor: Isaac Ghebre-Sellassie,Russell U. Nesbitt,Mahdi B. Fawzi
Year of patent: 1993
5 Patent no: US201000808494A1
Title: Pellets containing a pharmaceutical substance
Abstract: The invention relates to pellets containing a pharmaceutical substance with a
breaking strength of more than 0.001 newton, method of production thereof and
pharmaceutical preparations based on said pellets.
Inventor: Burkhard Schlutermann
Current Assignee:ADD ADVANCED DRUG DELIVERY TECHNOLOGIES LTD.
Year of patent: 2010
6 Patent no: US833788b2
Title: Pellet formulation for treatment of the intestinal tract.
Abstract: .An orally administerable pharmaceutical formulation for the treatment of
intestinal tract is disclosed, which comprises a core and enteric coating,the core including ,as
a pharmaceutical active compound,aminosalicylic acid or a pharmaceutically tolerable salt or
a derivative thereof.
Inventor: Norbert Otterbeck
Current Assignee: Dr Falk Pharma GmbH
Year of patent: 2012
7 Patent no: US5807583A
Title: Sustained release pellets
Abstract: A process for the manufacture of sustained released pellets comprising
pelletization a mixture containing the drug in finely divided form and a binder.
Inventor: Hening Kristensen,Torben Schaeer,Lars Juul Thomsen, Arne Kristensen
Current Assignee: Pfizer Health AB
Year of patent: 1998
8 Patent no: US20150079167A1
Title: Encased pellet tablets
Abstract: .An encased pellet tablet for an active pharmaceutical ingredients comprises an
excipient layer on the outside and an inner core that is surrounded by the excipient layer .The
inner core contains a plurality of coated pellets ,and the coated pellets comprise pellets of the
active pharmaceutical ingredient coated with a pellet coating.
Inventor: Harry G. cocolas,Christin P. Hollis
Current Assignee: RP Scherer Technologies LLC.
Year of patent: 20
9 Patent no: US2012020782A1
Title: Pharmaceutical pellets comprising modified starch and therapeutic applications
Abstract: Vaginal use compositions comprising pells prepared from a debranched
starch.Pellets may be conveniently prepared via extrusion/spheronization.
Inventor: Jean Paul Remon,Chris Vervaet,Paul Foreman
Current Assignee: Henkel AG and Co KGaA
Year of patent: 2012
10 Patent no: US10251840B2
Title: Methods for manufacturing acid pellets
Abstract: The invention relates to an improved method of manufacturing substantially
spherical shaped tartaric acid starter pellets which are suitable or preparing active substance
containing medicament formulations as well as the pellets as such that may be obtained in
this way and their use as starting material for the preparation of active substance containing
medicament formulation.
Inventor: Johann George Maier
Current Assignee: Boehringer Ingelheim International
Year of patent: 2019
