Powders and Granules

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Powders and Granules

• Dr. Basavaraj K. Nanjwade M. Pharm., Ph. D
• Department of Pharmaceutics
• Faculty of Pharmacy
• Omer Al-Mukhtar University
• Tobruk, Libya.
• E-mail nanjwadebk_at_gmail.com

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CONTENTS

• Definition, advantages, size shape, storage.
• Hard gelatin capsules (shell manufacture
  filling).
• Soft gelatin capsules (manufacturing and
  filling).
• Sustained release and enteric coated capsules.
• Formulation factors affecting bioavailability.
• Microencapsulation (Introduction, advantages).
• Coacervation phase separation technique.
• Pan coating, electrostatic deposition, spry
  drying.
• References.

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Definition of Powders

• A pharmaceutical powder is a mixture of finely
  divided drug and/or chemicals in dry form.
• Powders are solid dosage form of medicament which
  are meant for internal and external use.
• They are available in crystalline or amorphous
  form.
• The particle size of powder plays an important
  role in physical, chemical and biological
  properties of the dosage forms.

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Definition of Granules

• Granulation is the process in which primary
  powder particles are made to adhere to form
  larger, multiparticle entities called granules.
• Pharmaceutical granules typically have a size
  range between 0.2 and 0.4 mm, depending on their
  subsequent use.
• In the majority of cases this will be in the
  production of tablets or capsules, when granules
  will be made as an intermediate product and have
  a typical size range between 0.2 and 0.5 mm.

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Advantages of Powders and Granules

• Solid preparations are more chemically stable
  than liquid ones.
• Powders and granules are a convenient form in
  which to dispense drugs with a large dose.
• Orally administered powders and granules of
  soluble medicaments have a faster dissolution
  rate than tablets or capsules, as these must
  first disintegrate before the drug dissolves.

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Particle Size Powders and Granules

• Particle size is characterized using these terms
  
• Very coarse (8)
• Coarse (20)
• Moderately coarse (40)
• Fine (60)
• Very fine (80)

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Particle Shape Powders and Granules
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Different shapes of crystals
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Hard gelatin capsules (shell manufacture filling)

• These are used for administration of solid
  medicaments.
• The capsule shell is prepared from gelatin,
  colour and titanium dioxide to make it opaque.
• It consists of two parts i.e. body and cap.
• The powdered material is filled into the
  cylindrical body of the capsule and then the cap
  is placed over it.
• The empty capsules are available in various
  sizes.
• They are numbered according to the capacity of
  the capsules.
• The number starts from 000 and goes up to 5.

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Hard gelatin capsules (shell manufacture filling)
Capsule number Approximate capacity in mg
000 950
00 650
0 450
1 300
2 250
3 200
4 150
5 100
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Hard gelatin capsules (shell manufacture filling)
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Methods of filling the hard gelatin capsules

• The capsules can be filled either by hand or by a
  semi-automatic device or by an automatic filling
  machine.
• Capsule filling machine (Hand operated) It
  consists of-
• A bed having 200-300 holes
• A loading tray having 200-300 holes
• A powder tray
• A pin plate having 200-300 pins
• A sealing plate having a rubber top
• A lever
• A cam handle

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Soft gelatin capsules (manufacturing and
filling)

• These are used for administration of liquid
  medicaments. Soft gelatin capsules are available
  in round, oval and tube like shapes.
• They are made from gelatin. The gelatin is
  plasticized by the addition of glycerin and
  sorbitol etc.
• The soft gelatin shell may contain a preservative
  to prevent the growth of fungi.
• They are used to enclose liquid medicaments-oils,
  suspensions, food concentrates and ophthalmic
  products.

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Soft gelatin capsules (manufacturing and
filling)
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Method of filling of soft gelatin capsules

• Soft gelatin capsules are generally filled
  mechanically.
• The manufacturing of the capsule shell and the
  filling of the medicament take place
  simultaneously. Nowadays, a rotary machine is
  used for this purpose.
• Rotary die machine, the soft gelatin capsules are
  prepared and then filled immediately with the
  liquid medicaments.
• The machine consists of two hoppers.
• Liquid gelatin mixture is placed in one hopper
  and the liquid medicament in the other hopper.
• There are two rotating dies which rotate in
  opposite directions.

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Sustained release capsules

• In order to maintain a proper blood concentration
  of the medicament and reducing the number of
  doses per day, a capsule, containing numerous
  coated pellets, is administered that release the
  drug successively over a long period.
• The finely powdered drug is first converted into
  pellets.
• These pellets are treated with protective
  coatings that delay the release of the drug.
• The batches of pellets are mixed thoroughly and
  suitable doses are filled into capsules.

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Enteric coated capsules

• These capsules do not disintegrate in the stomach
  (acid medium) but break-up in the intestine
  (alkaline medium).
• A special type of treatment or coating is given
  to the capsules so that these can pass unchanged
  through the stomach but get disintegrated in the
  intestine.
• On a commercial scale, a coating of cellacephate
  (cellulose acetate phthalate) and mixtures of
  waxes with fatty acids or their esters is given.

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Enteric coated capsules

• The following categories of drugs need enteric
  coatings.
• Drugs which cause irritation to the gastric
  mucosa and lead to nausea and vomiting.
• Drugs which are destroyed by the gastric juices.
• Drugs which are specially intended to act in the
  intestine e.g. amoebicides and anthelminitics.
• Drugs which are required to produce a delayed
  action.

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Formulation factors affecting bioavailability

• The types of dosage form and its method of
  preparation or manufacture can influence
  bioavailability.
• Particular drug is incorporated and administered
  in the form of a solution, a suspension or solid
  dosage form can influence its rate and/or extent
  of absorption from the gastrointestinal tract.
• The type of oral dosage form will influence the
  number of possible intervening steps between
  administration and the appearance of dissolved
  drug in the gastrointestinal fluids.
• Types of dosage form aqueous solution gt aqueous
  suspensions gt solid dosage forms (e.g. hard
  gelatin capsules or tablets).

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Formulation factors affecting bioavailability
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Microencapsulation (Introduction)

• Microencapsulation is a process or technique by
  which thin coating can be applied to small
  particles of solids, droplets of liquids or
  dispersion, thus forming microcapsules.
• The microcapsules may consist of a single
  particle or clusters of particles.
• It differs from other coating methods because
  microencapsulation process is used to coat the
  particles having a particle size range from
  several tenths of a micro to 5000 ?.

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Microencapsulation (advantages)

• Advantages of Microencapsulation Process
• It is used for masking the taste of bitter drugs.
• It is used for preparing prolonged action dosage
  form
• It is used in modifying the physical characters
  of a material required in certain formulations
• The technique is used to separate an incompatible
  material
• It is used to protect chemicals against moisture
  and oxidation.

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Coacervation phase separation technique

• Coacervation means the separation of a liquid or
  phase when solution of two hydrophilic colloids
  are mixed under suitable conditions.
• In this method, the three immiscible phases of
  core material, solvent and coating material are
  formed followed by deposition of coating material
  on the core.
• The coating material is dissolved in a suitable
  solvent and the core material is uniformly
  dispersed in the solution of the coating
  material.
• Then the coating material is phased out of its
  solution which starts getting deposited on the
  particles of the core material.

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Pan coating

• In this technique the coating is done in a pan
  made up of copper or stainless steel.
• The pan is rotated with the help of an electric
  motor.
• The tablets to be coated are placed in the pan.
• Hot air is blown in, speed of the pan is adjusted
  in such a way that the tablet remain separated
  from each other in the pan.
• After coating, polishing is done in a polishing
  pan, pan coating technique is used for sugar
  coating, film coating and enteric coating.

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Pan coating
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Electrostatic deposition

• The method is useful both for solid particles and
  liquid droplets.
• In this process, the core and coating materials
  are electrically charged by means of high voltage
  such as 10, 000 volts etc.
• The core is charged and placed in the coating
  chamber.
• The coating material is also charged before it is
  sprayed as a mist.
• Because the charges are of opposite kind, the
  coating material gets deposited on the core due
  to electrostatic attraction.

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Spry drying

• The spray drying provides a large surface area
  for heat and mass transfer by atomizing the
  liquid to small droplets.
• Sprayed into a stream of hot air, so that each
  droplet dries to an individual solid particle.
• Spry drying ensures good air circulation,
  facilitates heat and mass transfer and encourages
  the separation of dried particles from the moving
  air by the centrifugal action.
• The character of the particles is controlled by
  the droplet size, and so the type of atomizer is
  important.

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Spry drying
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