Filling Of Hard Gelatin Capsules

Submitted by :Simranjit SinghM.Pharm- 2nd Sem

Submitted to :Dr. Swati Gupta

Materials that can be filled into hard gelatin capsules:

Powders/Granules Pellets Tablets

Basic Steps involved in the filling of hard gelatin capsules:

Supply of Empty Capsules

Aligning and Rectification

Opening and Separation

Filling of Powder Granules/Pellets

Joining and Closing

Discharge

1. Rectification:

• The empty capsules are oriented so that all point in the same direction. i.e., body end downward.

• A specially designed blade pushes against the capsule and causes it to rotate about its cap end as a fulcrum.

• After two pushes (one horizontally and one vertically downward), the capsules will always be aligned body end downward regardless of which end entered the channel first.

2. Separation of caps from bodies:

• This process depends on the difference in diameters between cap and body portions.

• Here, the rectified capsules are delivered body end first into the upper portion of split bushings or split filling rings.

• A vacuum applied from below pulls the bodies down into the lower portion of the split bushing.

• The diameter of the caps is too large to allow them to follow the bodies into the lower bushing portion.

• The split bushings are then separated to expose the bodies for filling.

3. Dosing of Fill Materials:

Various methods are employed for it.

Fig. Vacuum assisted Capsule opening in automated Capsule-Filling Machine

4. Replacement of caps and ejection of filled capsules:

• The cap and body bushing portions are rejoined. • Pins are used to push the filled bodies up into the caps for

closure and to push the closed capsules out of the bushings. • Compressed air also may be used to eject the capsules.

Types of Machines Used

Semi-automatic Fully -automatic

• Semi-automatic machines such as the Type 8 machines (e.g. Capsugel’s Cap 8 machine) require an operator to be in attendance at all times.

• Depending on the skill of the operator, the formulation, and the size of the capsule being filled, these machines are capable of filling as many as 120,000— 160,000 capsules in an 8-hour shift.

• Automatic capsule filling machines may be classified as either intermittent or continuous motion machines.

• Intermittent machines exhibit an interrupted filling sequence as indexing turntables must stop at various stations to execute the basic operations described above.

• Continuous motion machines execute these functions in a continuous cycle.

Make/Model Dosing principle

Motion Rated capacity (capsules/hr)

BoschGKF 400SGKF 2000SGKF 3000

Dosing disc IntermittentIntermittentIntermittent

24,000

150,000180,000

IMAZanasi 6Zanasi 40Matic 60Matic 120

Dosator IntermittentIntermittentContinuousContinuous

6,000

40,00060,000

120,000

MG2FuturaG60G120

Dosator ContinuousContinuousContinuous

48,00060,000

120,000

Table: Selected Automatic capsule-filling machines:

Powder Filling: Following equipment and dosing methods may be identified for powder filling:

1. Auger Fill

Fig. Capsule Filling with the Auger Method

• Capsule filling using the auger principle is the oldest semi-automatic filling technique.

• The general filling principle is illustrated in Figure by Capsugel type 8 machines.

• The powder or granules are contained in a hopper similar in design to mass-flow hoppers. Inside these is a rotating auger to which a stirrer is attached.

• Powder is fed continuously out of the hopper outlet owing to the rotation of the auger into the capsule bodies.

Fig. Double Screw Auger Used in the LiqFil Super Machines

• The empty capsule bodies are placed into the bushings of a rotating turntable ( pick up ring) and will pass the hopper outlet during the rotation process.

a) Sandwich of cap and body rings positioned under rectifier to receive empty capsules. Vacuum is pulled from beneath the rings to separate caps from bodies.

b) Body ring ¡s positioned under foot of powder hopper for filling.

c)After filling the bodies, the cap and body rings are rejoined and positioned in front of pegs. A stop plate is swung down in back of rings to prevent capsule expulsion as the pneumatically driven pegs push the bodies to engage the caps.

d) The plate is swung aside and the pegs are used to eject the closed capsules.

• The fill of the capsules is primarily volumetric. The amount of powder fed directly into the capsule body depends on the: time the capsule body spends underneath the hopper outlet, capsule size, on the auger speed and on the twist angle of the auger.

• Slower rotation of the turntable increases the fill weight, because the capsule bodies remain underneath the hopper outlet for a longer time span. An Increase In the auger speed and a steeper twist angle will also increase powder fill weight.

Glidants: such as colloidal silica improve the flow properties of the powder blend from the hopper and they also assure a uniform flow rate from the hopper. The presence of 3% talc reduces weight variation compared to 0% talc.

• Lubricants: such as magnesium stearate and stearic acid facilitate the passage of the filling ring under the foot of the powder hopper and help preventing the adherence of certain materials to the auger

2. Vibratory fill principle:

Vibration-assisted filling is a method introduced in 1960 by the Osaka Company (Japan).

Figure illustrates the individual steps of the filling procedure.

• The powder is directly filled into the capsule bodies. • The capsule bodies are again positioned into a rotating

turntable and pass underneath the powder bowl.• The powder bowl has a mesh floor connected to a

mechanical vibrator. Powder or granules pass the mesh floor whereby the vibration assists with desagglomeration and flow.

• The capsule bodies are filled to the maximum extent plus more powder on top, filling the cavities of the turntable completely.

• Further rotation at the turntable positions the capsule bodies so that a spring-loaded plunger can compress the powder inside the dosing bores to a more or less firm plug. A fixed counter plate underneath the turntable assists with this.

• The capsule body now contains a powder plug usually considerably longer than the size of the body itself.

• The complete capsule body is now pushed upwards so that the powder plug ¡s partially outside the turntable bores.

• A scraper removes the powder outside the turntable bores and the capsule bodies are pushed further upwards to be joined to the corresponding cap and dosed.

• The final fill weight is hence adjustable via the following mechanisms: rotation speed of the turntable and extent of vibration compression setting of the plunger Final plug length defined by the amount of lift and the action

of the scraper.

• This system works well for dense, free-flowing powders. • The system is commercially available as Liqfilsuper 40 (Shionogi Qualicaps, Japan),

producing up to 40 000 capsules per hour. • All sizes between 00 and 5 can be filled except for non-standard capsules.

Piston tamp Principle

• These are fully automatic fillers in which pistons or tamping pins lightly compress the individual doses of powders into plugs (sometimes referred to as “slugs”) and eject the plugs into the empty capsule bodies.

• The powder is tamped into the dosing bores by compression pins (tamping fingers)

• The tamping is repeated five times to firm an individual powder plug and at the sixth tamping event, the final plug is pushed into the capsule body.

• To avoid the powder being pushed through the dosing bores, the dosing disc rotates over a brass support ring (tamping ring)

There are two types of piston tamp principles:

1. Dosing Disc Machines2. Dosator Nozzle Machines

1. Dosing Disc machines:

Fig: Tamp-Filling Mechanism of Dosing Disc Machine: The five tamping stations plus transfer station are positioned on a circular path

Fig. Intermittent Dosator Nozzle Filling Principle

2. Dosator nozzzle machines:

• The powder is fed via a powder hopper into the dosing hopper which rotates and a metal plate positioned behind the hopper outlet inside the dosing hopper controls the powder bed height.

• The dosators are lined in pairs for their operation.

• A dosator nozzle consists of a hollow dosing tube, inside which is a movable piston.

• The initial position of the piston inside the tube defines the volume and consequently the weight of the powder plug to be formed.

• The dosator nozzle is lowered into the powder bed and the powder enters into the dosing tube and is compressed.

• The dosator niozzle is then lifted up from the powder bowl.• At the same time, the powder nozzle is positioned over the

capsule body and the powder plug is pushed out of the dosing tube by the piston being moved down to the end of the tube

• After the nozzles have been lifted, they swap position so that the newly formed plug can be released into a new capsule body and at the same time the second nozzle is lowered into the powder bed.

Fig. View of the rotary dosing unit of G140 Continous Dosator Nozzle Capsule-Filling Machine

Fig. Zanasi Matic 90 automatic capsule-filling machine

MG2 Futura Automatic Capsule Filling Machine

Vacuum-Filling Method

• The vacuum method is based on a continuous dosator nozzle principle.• The moving piston has been replaced by a piston fitted with a porous

plate at the power end. Its position remain fixed during the complete filling process.

• The upper end of the dosing tube is connected to an airflow system.• When the nozzle is dipped into the powder bed, powder is sucked into

the cavity formed by dosing tube and piston plate.• When the nozzle is position over the capsule body, the suction is

revered into a mild air blow, which transfers the powder into the capsule body.

• Powder filled with this mechanism is less densified, very small doses can be filled and owing to the fact that there are no moving parts inside the dosing tube, the need for a lubricant in the formulation is limited and often no lubricant is required.

• This makes such a system ideal for filling low doses and inhalational products.

Fig. : Vacuum assisted filling of Hard gelatin capsules

Filling of pellets:

• Filling of pellets in to hard capsules requires separate techniques from those used for powders and granules, because pellets are larger in size and cannot be compressed and often they are coated with a film to control drug release.

• In the first step, pellets flow form the pellet magazine into the dosing chamber.

• The size of the dosing chamber can be varied by moving the left chamber slide closer or further apart form the right wall of the dosing chamber.

• The dosing slide is then moved to the left whereby it closes the dosing chamber from the pellet magazine.

• At the same time, the outlet moves to the right, and opens the dosing chamber at the bottom end, so that the pellets can flow through the conical outlet into the capsule body.

• Reversing the moving of the dosing and the outlet slide starts a new filling cycle.

Fig: Filling of pellets with double slide mechanism

Fig. Filling of Pellets with modifying dosing disc system

Fig. Filling of pellets with vacuum assisted dosator nozzle system

REFERENCES:

1 . Podczeck Fridrun and Jones E Brian , Pharmaceutical capsules 2nd edition , Pharmaceutical Press, Page no. 119-137

2. Banker Gilbert S. and Rhodes Christopher T. , Modern Pharmaceutics, 4th edition, Marcel Dekker, Page no. 347-356