Photostabilization by Packaging

Institutfur Pharrmzie—Zentrumfiir Pharmaforschung, Lehrstuhlfur Pharmazeutische Technologie, Ludwig-MaximiliansAJniversitat, Munich, Germany 

Research and Development, Gebro Pharma GmbH, Fieberbrunn, Austria 

One of the primary methods used for protecting liquid and solid photolabile pharmaceuticals and preparations from photodegradation is to package them in colored glass or plastic. Colored/pigmented containers are also suitable for the photostabilization of sterile preparations, such as eye drops. 

The European Pharmacopoeia requires testing of the UV and VIS radiation permeability of glasses used for the packaging of pharmaceuticals. Generally, the glass s transmission is measured between 290 and 450 nm. 

For colored glass containers, not intended for parenteral preparations, the measured transmission must not exceed a maximum value of 10% at any wavelength between 290 and 450 nm, irrespective of the size or glass type. The limits for colored glass containers, used for parenteral preparations, depend on their intended fill volume. The respective limits for these containers are given in Table 1 (3,4). 

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Most neat plastic materials used for packaging of pharmaceutical products absorb UV-VIS radiation below 280 nm. Therefore, photostabilization by plastic packaging is only possible by the addition of colorants, UV absorbers, or pigments to the plastic mass. 

For infusion liquids, no completely UV-VIS photon impermeable immediate package can be used. These products require dilution and the inspection for particulates before use both processes hindered by such packaging. To guarantee safe application/dosing additional photostabilizing packaging is applied for extremely photosensitive drug preparations. 

Tablets can also be photostabilized using aluminum blister packs. This photostabilization method is used by some nifedipine tablet manufacturers. Nifedipine tablets packaged in aluminum foil unit dose blisters do not require any additional photo protection (e.g., coating), providing a significant saving in development and manufacturing costs as well as stability testing (40).

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