Degradation of Drugs in light
Many drugs are prone to degrade in Presence of light. So, the impact of light on physical and chemical attributes of drug substance must be identified in order to prevent its degradation. International conference on harmonization Q1b provides guidelines for photostability testing of new drug substances.
In presence of light some Active pharmaceutical ingredients starts degrading and forms new compounds which may harm patient. The degradation occurs because Light carries energy in form of photons which induces the Chemical reaction in active ingredient leading to its degradation and formation of impurities.
Photo degradation of Active pharmaceutical ingredients generally occurs at the wavelength of 300-500 nm. However, Some drugs degrade at particular wavelength which should be identified at product development stage.
To prevent degradation of light sensitive drugs
- During manufacturing of photosensitive drugs larger wavelengths should be used i.e above 500 nm upto 800 nm.
- Degradation of drugs at some Particular wavelength should be identified.
- Colored coating should be used in case of light sensitive products as colored coating will not allow the light to reach active ingredient.
- Packing of light sensitive products must be done in Amber colored blisters or Alu-Alu packing.
- Light sensitive injectables should be packed in Amber colored vials.
- Calibration of Lux meter(Instrument to check intensity of light) must be done.
Light may cause error in Analytical results during testing of light sensitive pharmaceutical products. So, testing must be carried out in controlled light conditions to get accurate testing results.
Storage of control samples must be done in Dark amber colored bottles wrapped with Aluminium foil.