Characterization of tablet film coatings using a laser-induced breakdown spectroscopic technique

Abstract

Laser-induced breakdown spectroscopy (LIBS) was evaluated as an early phase process analytical technology (PAT) tool for the rapid characterization of pharmaceutical tablet coatings. Measurement of coating thickness, uniformity, and photodegradation-predictive potential of the technique were evaluated. Model formulation tablets were coated with varying amounts (2%-4% wt/wt) of red and yellow Opadry II, and a pulsed laser was used to sample at multiple sites across the tablet face. LIBS was able to successfully detect the emissions of Fe and Ti in the coated samples, and a proportional increase in signal with coating thickness was observed. Batch-to-batch variability in the coating procedure was also easily monitored by LIBS. The coating thickness was non-uniform across the tablet surface with higher thickness at the edges, likely due to the concave shape of the tablet. Film coating levels and color of the film had been subjected to photostability studies according to the International Conference on Harmonisation (ICH) guideline to determine effectiveness of the film coats. LIBS measurements of coating thickness provided a good correlation (R 2 9 0.99) to photodegradation as measured by high-performance liquid chromatography (HPLC). Last, the concentration of Fe in the coating was varied and monitored by LIBS. Increasing photostability was observed with increasing levels of ferric oxide, providing a new understanding of the photoprotection mechanism in the coated formulation. Determination of levels of ferric oxide and coating thickness by LIBS demonstrated its utility as a good PAT tool for the determination of photoprotection of the drug, thereby enabling facile optimization of the coating process.

Intra-tablet coating variability for several pharmaceutical tablet shapes

“…Much of the previous work has focused on methods for measuring the coating thickness on a tablet using techniques such as direct film thickness measurements (Wilson and Crossman, 1997), near-infrared spectroscopy (Pé rez-Ramos, 2007), terahertz imaging (Taday, 2008), laser induced breakdown spectroscopy (Madamba et al, 2007), and Raman spectroscopy (Müller et al, 2010). These tools have shown that the coating thickness can vary widely over a tablet's surface.…”

“…In general, tablets tend to have a thicker coating on their faces and a thinner coating on their bands. Most researchers report that the coating becomes thinner moving from the center of the tablet face toward the edge with the band (Pé rez- Ramos, 2007;Taday, 2008), although Ho et al (2007) and Madamba et al (2007) found that in some cases the coating becomes thicker when approaching the edge.…”

Analysis of Pharmaceutical Tablet Coating Uniformity by Laser-Induced Breakdown Spectroscopy (LIBS)

“…The pharmaceutical industry is beginning to consider this technique for in-line monitoring and product analysis applications. However, there is not a lot of work published in the literature that deals with the specific application of this technology for pharmaceutical applications [29][30][31][32][33].…”

Computational Approaches for Studying the Granular Dynamics of Continuous Blending Processes, 1 – DEM Based Methods

“…Mathematical modeling and numerical simulation techniques have been applied for understanding mixing mechanisms in many types of batch blenders such as the Vblender, [10][11][12] tote-blender, [13,14] double cone blender, [15,16] and simple rotating drum. [17] Several other types of blenders have been studied using computational techniques.…”