Film coating application for Soft Gel Capsules

Soft capsules are oral solid forms where the active principal ingredient (inner fill) is usually placed inside a solid capsule (outer shell). Soft gelatin capsules (SGC) are often coated with a film layer for different reasons, such as protection against degradation, functionality, masking bad taste, and patient compliance.

Challenges the industry faces during gelatin capsule film coating- Romaco

Your challenges

Special roughness of the SGC surface
Low solubility of the capsule shell in organic solvents as carriers do not adhere properly to the shell
Defects on the film coating, such as peeling or cracking of the film layer
Swelling or sticking together of the capsules during the process due to plasticity effect of water when using aqueous or hydroalcoholic suspensions

Our solution

Proposing initial process parameters for the film coating of SGCs with a 100% aqueous suspension:

The key point of the coating process is to stabilize the equilibrium between the amount of energy provided by the inlet air flow and inlet temperature versus the amount of coating suspension provided.
The coating of 50 kg of SGCs was carried out in a TPR 100 OPT coating machine.
The coating formulation is shown in Table 1. The SGCs were mainly composed of sunflower oil and gelatin.
Process parameters were adjusted in such way that whole spraying time was 90 minutes to achieve a 3% weight gain. Process parameters used during this trial are listed in Table 2.

Table 1. Coating Composition

Coating suspension components
Purified water	83.0 %
Vivacoat® A	17.0 %
Red iron oxide	0.05 %

Table 2

Phase	Heating	Spraying	Drying
Drum speed (rpm)	3	8	3
Inlet air Flow (m3/h)	1600	1600	1000
Underpresure (Pa)	250	250	250
Inlet air T (°C)	48	48	32
Product temperature (°C)	37	37	33
Outlet air T (°C)	42	40	33
Spray rate (g/min)	-----	100	-----
Atomization pressure (bar)	-----	2.0	-----
Spray pattern pressure (bar)	-----	2.0	-----
Nozzle (mm)	1.2 (2 guns)	1.2 (2 guns)	1.2 (2 guns)
Gun distance from tablets (mm)	160	160	160
Batch size (kg)	50	50	50
Coater drum filling (%) Bulk density 0.6 Kg/L	55%	55%	55%
Sprayed solution (kg)	-----	8.8	-----
Process time (min)	20	90	15
Appearance quality	Acceptable	Acceptable	Acceptable

Conclusion - gelatin capsule film coating- Romaco

Our Conclusions

The film coating of a 50 kg batch (around 55% capacity of a TPR OPT 100) of soft gelatin capsules has been carried out. The challenge of performing an aqueous coating process while maintaining the process temperature below the melting point of the gelatin capsules has been successfully achieved. The TPR 100 OPT managed to keep all process parameters stable throughout the whole process, which was the main factor for the success of the trial.

Suitable Products

Tecpharm

TPR OPT Tablet Coater

Applications

Maximum output (liters)

7.5–900

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Tecpharm

TPR Standard tablet coater

Applications

Maximum output (liters)

3.5–900

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Application Note

Film coating application for Soft Gelatine Capsules

The film coating of a 50 kg batch (around 55% capacity of a TPR OPT 100) of soft gelatin capsules

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