Photostabilization of Capsules

For the photoprotection of drugs in soft gelatine capsules, the shell thickness must be sufficient and homogeneous. Lower shell thickness may occur especially in the sealed area. This thickness in homogeneity can lead to varying photodegradation rates depending on the irradiated area. 

The photostability testing of commercial nifedipine in soft gelatine capsules revealed remarkable differences if the capsules were irradiated in parallel to the seal. One preparation (W 10) produced a 10-fold greater amount of the nitrosophenyl 

Irradiation of gelatine capsules may not only result in photodegradation of the drug but may also affect the bioavailability of the drug. Irradiated gelatine films showed a decrease of their water vapor transmission. Even though this effect did not occur with indomethacin capsules, long-term irradiation resulted in increased dissolution rates (42). 

Microencapsulation of photosensitive drugs is another way of photostabilization. The photostability of ubidecarenone microcapsules could be improved by incorporating 

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