Using response surface methodology to quantify iron oxide levels needed to protect photolabile active pharmaceutical...

Area of Science:

• Pharmaceutical Sciences
• Materials Science

Background:

• Titanium dioxide (TiO2) is a crucial excipient in pharmaceutical film coatings, providing opacity and photoprotection for oral solid dosage forms.
• Regulatory actions, including a food ban and upcoming review for medicinal use, necessitate the identification of TiO2 alternatives.

Purpose of the Study:

• To evaluate iron oxides as potential replacements for TiO2 in pharmaceutical film coatings, focusing on their photoprotective capabilities.
• To determine effective concentrations of red, yellow, and black iron oxides in TiO2-free film coatings for photolabile active pharmaceutical ingredients (APIs).

Main Methods:

• A mixture model design of experiments (DOE) was employed to assess the photoprotective efficacy of three iron oxides (red, yellow, black).
• Tablets containing a model photolabile API were coated with varying concentrations of iron oxides in a polyvinyl alcohol (PVA)-based, titanium dioxide-free (TF) film-coating system.
• Photodegradation was quantified to evaluate the protective effect of the iron oxide-containing coatings.

Main Results:

• Red and yellow iron oxides significantly reduced the total photodegradation products of the model API.
• Incorporating 1-1.5% red or yellow iron oxide achieved 75-85% photoprotection.
• Concentrations of 2% or greater red iron oxide provided nearly complete photoprotection.
• Results were confirmed using a second photolabile API.

Conclusions:

• Red and yellow iron oxides are viable alternatives to TiO2 for providing photoprotection in pharmaceutical film coatings.
• Specific concentrations of these iron oxides can effectively mitigate API photodegradation, ensuring product stability and appearance.