NTA Level 6 • Semester 1 • PST06103

Filling Hard Gelatin Capsules

Pharmaceutical Production • Source Session/Topic 13

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Session 13: Filling Hard Gelatin Capsules

Total Session Time: 120 minutes

Pre-requisites

• None

Learning Tasks

By the end of this session students are expected to be able to:

• Explain the general process for hard gelatin capsule filling

• Explain the methods for hard gelatin capsule filling

• List types of hard gelatin capsule filling machines

• Explain working of hard gelatin capsule filling machines

• Explain the sealing of hard gelatin capsules

• Explain the process of cleaning hard gelatin capsules after manufacturing

• List common problems encountered during hard gelatin capsule production

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board and chalk/whiteboard markers

• LCD projector and computer

SESSION OVERVIEW

SESSION CONTENTS

STEP 1: Presentation of Session Title and Learning Tasks (5 minutes)

READ or ASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: General Filling Process (10 minutes)

• Filling of hard gelatin capsule shells involves a working process with

the following steps;

o Rectification (orientation of the empty capsule shells in same

direction)

o Separation of caps from the body

o Filling the bodies (bench-scale filling or industrial-scale filling)

▪ E.g. Auger filling principle (flat blade auger or crew auger)

o Scraping the excess powder

o Replacing the caps

o Sealing the capsules

o Cleaning the outside of the filled capsules

STEP 3: Filling Methods (35 minutes)

• Powders and granules can be filled by direct or indirect methods

o Direct Filling Methods

▪ The Punch Method

▪ This method is used for small scale filling e.g. filling a

small number of capsules in a pharmacy

▪ The powder is placed on a clean paper or porcelain plate and

formed into a cake

▪ The empty capsule body is punched vertically into the powder

cake repeatedly until filled

▪ Feston Capsule Filling

▪ This methods employs a hand operated capsule filling machine

▪ With this method, about 200-2000 capsules can be produced per

hour

▪ Empty capsules are placed on a loader tray which is placed on

top of the filler unit of the machine

▪ The loader inserts the capsules into the filling unit and is

removed and the top plate is lifted to separate the caps from

the bodies

▪ The powder is placed on the unit and the capsule bodies are

filled

▪ The top plate is returned to the unit and the caps placed on

filled capsule bodies

o Indirect Filling Methods

▪ Auger-filling Principle (dependent dosing system)

▪ Employs rotating augers mounted in the hopper and allow a

constant flow of powder or granules to the capsules at a

constant rate (flat bed auger or screw auger)

▪ Amount of powder fed into the body of the capsules depends on

the time the capsule body spends under the hopper outlet and

auger speed

o Slower rotation of the auger increases fill weight

o It is a semi-automated operation

o The powder is filled by volume (the capsule body measures the

powder or granules)

o Requires the powder to have good flow properties

▪ Vibration-filling Principle

▪ A perforated resin plate is positioned in the powder and

connected to a vibrator

▪ The powder blend is fluidized by vibration of the plate and

assists the powder to flow into the bodies through the holes in

the resin plate

▪ This is also known as vibration-assisted filling

▪ Piston Tamp Principle (independent dosing system)

▪ In this method, pistons or taming pins lightly compress the

individual doses of powders into plugs (also called slugs) and

eject the plugs into empty capsule bodies

▪ Dosator

▪ Consists of cylindrical dosing tube fitted with movable

piston

▪ Position of the piston is preset to a particular height to

define volume of the capsule

▪ Powder enters the open end of dosator and is slightly

compressed against the piston into a plug

▪ The capsules are filled based on weight

▪ Dosing disc

o Filling is done on the basis of weight

o A solid stop brass plate slides down the dosing disc to close

the hole

o Five sets of pistons compress the powder into cavities to

form plugs

• Filling of pellets into hard gelatin capsules may be accomplished

through;

o Double slide method

▪ Pellets flow from pellet magazine to dosing chambers

▪ Dosing slide is closed to separate dosing chamber and pellet

magazine

▪ Outlet slides open

o Vacuum-assisted method

▪ Dosing tube enters pellet bed

▪ With the help of vacuum, the pellets are sucked into the dosing

tube

▪ Excel pellets are scraped off the end of the dosing tube

▪ Dosing tube is lowered and pellets released into capsule body

• Filling of tablets into hard gelatin capsule shells

o Dosing slide which can accommodate exactly one tablet moves under the

tablet feeder

o Slider moves over the capsule body where the tablet simply drops into

o If properly filled, the pin dropped into the capsule body will have

limited movements, the horizontal bare connected to the in touches a

sensor

o If not properly filled, the horizontal bar will switch the sensor

indicating incorrect filling

o Empty capsules can be detected and eliminated from the product

• Filling Semisolid Mass in Hard Gelatin Capsules

o If the material to be placed into hard gelatin capsules is a

semisolid, it can be encapsulated by either forming a pipe or pouring

a melt

• Filling Liquids in Hard Gelatin Capsules

o Liquids can be prepared in hard gelatin capsules if the gelatin is not

soluble in the liquid to be encapsulated

▪ E.g. alcoholic solutions and fixed and volatile oils

▪ Solubility of gelatin in the liquid may be determined by

experimentation

o The liquid is measured using a pipette (micropipette) or a calibrated

dropper and dropped into the body taking care not to touch the opening

o The gelatin caps are moistened at the open ends by touching them on a

moist towel or in warm water to soften the gelatin at the opening of

the caps

o The cap is then placed over the body containing the liquid with a

slight twist and the softened edge of the cap forms a seal with the

body to prevent leakage

▪ The capsules are observed for leakage before packaging them

STEP 4: Capsules Filling Machines (25 minutes)

• The process of encapsulation of hard gelatin capsules may be done using

manual, semi-automatic and automatic capsule filling machines

• Filling Solids in Hard Gelatin Capsules

o Manual/Hand Operated Capsule Filling Machines

▪ The machine are made up of a bed with 200-300 holes, a pin plate

with 200 or 300 pins corresponding to the number of holes in the

bed, a capsule loading tray, a powder try, a lever, a handle and a

sealing plate with rubber top

▪ All parts of the machines are made up of stainless steel

▪ The machines are generally supplied with additional loading

trays, beds, and pin plates with various diameters of holes so as

to fill the desired size of the capsules

▪ These machines are very simple to operate, can be easily

dismantled and reassembled

▪ Operation

▪ The empty capsules are filled into the loading tray which is

then placed over the bed

▪ By opening the handle, the bodies of the capsules are locked

and caps separated in the loading tray itself which is then

removed by operating the liver

▪ The weighed amount of the drug to be filled in the capsules is

placed in powder tray already kept in position over the bed

▪ The powder is spread with the help of a powder spreader so as

to fill the bodies of the capsules uniformly

▪ Excess powder is collected on the platform of the powder tray

▪ The pin plate is lowered and moved downward to press the

powder in the bodies

▪ The powder tray is removed and the caps holding tray is placed

in position

▪ The caps are pressed with the help of the plate with rubber

top and the lever is operated to unlock the cap and the body of

the capsule shells

▪ The loading tray is removed and filled capsules in a tray

▪ With 200-hole machine, about 5,000 capsules can be filled per

hour and with 300 hole-machines 7,500 capsules can be filled per

hour.

o Semi-automatic and Automatic Capsule Filling Machines

▪ On large-scale manufacturing various types of semiautomatic and

automatic machines are used

▪ They operate on the same principle as manual filling, namely the

caps are removed, powder filled in the bodies, caps replaced and

filled capsules are ejected out

▪ With automatic capsule filling machines powders or granulated

products can be filled into hard gelatin capsules

▪ With accessory equipment, pellets or tablets along with powders

can be filled into the capsules

▪ Examples of automatic capsule filling machines;

▪ Farmatic, capacity 40,000-160,000 capsules per hour, dosator

type feeding units

▪ Hofliger and Karg, fills pellets, tablets and thixotropic

liquids, follows auger principle

▪ Osaka, high capacity, continuous motion, follows vibratory

filling principle, capacity up to 400,000 capsules per hour

o Capsule Filling Devices

▪ A number of different manually operated capsule filling devices

are commercially available for filling up to 50 or 100 capsules at

a time

▪ The method of using these machines requires a careful

determination of the capsule formulation

▪ The powder is blended properly and the empty gelatin capsules are

placed into the device and oriented so that the cap is on top

▪ The machine is worked to separate the base from the cap and the

portion of the machine holding the caps is removed and set aside

▪ The capsule bases are allowed to “drop” into place so that the

tops are flush with the working surface

▪ The powder mix is careful, uniformly and evenly spread over the

working surface with the aid of a plastic spatula

▪ The powder is evenly filled into the capsule bases or the machine

can be “tapped” to spread the powder and drop it down into the

capsule bases

▪ A small device consisting of several “pegs” on a handle can be

used to tamp the powder into the capsule bases gently and evenly

▪ Any remaining powder is spread evenly over and into the capsule

bases and tamped

▪ The procedures are repeated until all of the powder is in the

capsules

▪ The capsule caps are then fitted over the machine, fixed in

place, and the filled capsules removed, dusted using a clean cloth,

and packaged

• Industrial scale Hard Gelatin Filling

o Machines developed for industrial use automatically separate the caps

from the empty capsules and fill the bodies

o The machines for industrial -scale filling of hard gelatin capsules

come in many shapes and sizes, varying from semi- to fully automatic

and ranging in output from 5000 to 15000 per hour

o Automatic machines can be either continuous in motion, like a rotary

tablet press, or intermittent, where the machine stops to perform a

function and then indexes round to the next position to repeat the

operation on a further set of capsules

STEP 5: Sealing the Capsules (15 minutes)

• Capsule sealing is done by the following methods;

o Tamper evident capsules by sealing the joint between the two capsule

parts (head and the body)

o Distinctive looking capsules by sealing them with coloured band of

gelatin. If removed, the band cannot be restored without expert

sealing with gelatine

o Through a heat welding process that fuses the capsule cap to the ring

around the capsule where the head welded (e.g. Weld’s gelatin seal)

o Capsules may also be sealed through a heat welding process that fuses

the head to the body

o Light coating the inner surface of the cap with a warm gelatin

solution immediately prior to placement on the filled capsule body

STEP 6: Cleansing and Polishing Process (10 minutes)

• Small amount of powder may adhere to the outside of capsules after

filling

• It is imperative that every precaution to minimize traces of moisture or

body oils on capsules be taken to reduce powders sticking to the surface,

which would create disagreeable appearance and taste

• Cleaning capsules is difficult if they have become moist or sticky

• The capsules should be handled so that they retain their dryness and

shiny appearance.

• Use of gloves provides a more hygienic environment and helps preserve the

dry, shiny capsule appearance

• On a small scale, capsules may be cleaned individually or in small

numbers by rubbing them with a clean gauze or cloth (cloth dusting)

• On large scale, many capsule filling machines are affixed with a cleaning

vacuum that removes any extraneous material from the capsules as they

exit the equipment.

o Industrial cleaning and polishing of filled hard capsules can be done

e.g. by the Accela-cota apparatus

STEP 7: Common Problems during Manufacturing of Capsules (10 minutes

• Filling of deliquescent/ hygroscopic powder

o Remedy

▪ Addition of adsorbent e.g. magnesium carbonate/light magnesium

oxide

• Filling of eutectic mixture

o Remedy

▪ Use of adsorbent e.g. Magnesium carbonate, kaolin

• Small dose of drug

o Remedy

▪ Addition of inert powders (fillers)

• Incompatibilities of materials

o Remedy

▪ Use of two capsules –small in large

• Lack of adhesiveness difficult to fill by punch method

o Remedy

▪ Moistened with alcohol, granules reduced to powders

STEP 9: Key Points (5 minutes)

• Filling of hard gelatin capsule shells involves rectification

(orientation of the empty capsule shells in same direction), separation

of caps from the body, filling the bodies (bench-scale filling or

industrial-scale filling), scraping the excess powder, replacing the

caps, sealing the capsules, cleaning the outside of the filled capsules

• Powders and granules can be filled by direct or indirect methods

• Machines developed for industrial use automatically separate the caps

from the empty capsules and fill the bodies

STEP 10: Evaluation (5 minutes)

• Mention the steps involved in filling of hard gelatin capsule shell

• What are the common problems encountered in capsule manufacturing?

• What is the importance of capsule sealing?

References

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manufacture of medicines, (4th ed.) Churchill Livingstone

Hugo and Russell (2011), Pharmaceutical Microbiology (8th ed.) , Willey-

Blackwel publications

Gennaro, R. A, et al. (eds) (1995) Remington: The Science and Practice of

Pharmacy, Volume I & II, (19th ed.): Mack Publishing Company, Easton,

Pennsylvania 18042

Liebsch, B et al (1988): Tanzania Pharmaceutical Handbook, Dar es Salaam

University Press.

Lund, W. Editor (1994). The Pharmaceutical Codex, Principles and Practice

of Pharmaceutics (12th ed.): The Pharmaceutical Press, London

Polderman, J (1990) Introduction to Pharmaceutical Production: Novib, The

Hague

Rawlins E.A, Editor: (1977) Bentley’s Textbook of Pharmaceutics, (8th ed.)

Baillie're Tindall. London Kamm, G. and Kohler, B. Editors: (1995)

Manual for Decentralized Infusion Production, Infusion Unit Project

Tanzania

Schmidt, O. (ed) (2000) Pharmaceutical Quality systems, Interpharm Press,

Colorado.

Shayne C et al. (2008), Pharmaceutical Manufacturing Handbook: Production

and processes, John Wiley & Sons

Watson, D. G (1999) Pharmaceutical Analysis: A Textbook for Pharmacy

Students and Pharmaceutical Chemists: Churchill Livingstone,

Edinburgh.

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