(W1130-07-46) Evaluation of Stability and Functional Packaging Effectiveness for Ferrous Ascorbate Tablets Coated with Aqueous Moisture Barrier Film Coating Formulation

Purpose: Ferrous ascorbate tablets are highly hygroscopic, necessitating scientific consideration of core and coating components along with an auxiliary packaging components (functional packaging) to ensure enhanced formulation stability (1). This study focuses on coating tablets with a high-performance moisture barrier film coating system (Opadry^® amb II), followed by adding various functional packaging solutions, including desiccants and polymer-based oxygen scavenging canisters(PharmaKeep^®) at varying grammage levels. Formulation will be evaluated at accelerated stability conditions to determine the most effective coating and packaging combination for maintaining the product’s quality throughout the storage period.

Methods: Selection of Tablets and Functional Packaging: Ferrous ascorbate and folic acid tablets, each containing 100 mg of elemental iron and 1.5 mg of folic acid, with a core weight of 920 mg and a capsule shape, manufactured by Emcure Pharmaceuticals Ltd., were selected to ensure uniformity for the study. Seven functional packaging configurations were designed to evaluate their effectiveness in protecting moisture sensitive core formulations alongside a moisture barrier film coating formulation system, as outlined in the Table 1. Coating of Tablets: Core tablets were coated with Opadry^® amb II 88ZA565008 Brown at 4% weight gain with 20% w/w solids in water. The tablet coating process was performed in a 15-inch fully perforated coating pan (O’HARA Labcoat™, model LCM-5), with a batch size of 2 kg. Coating parameters: inlet temperature of 62 to 64°C; exhaust temperature of 45 to 46°C; product temperature of 45 to 46°C; spray rate of 7 - 8 g/min; atomizing air pressure of 1.4 - 1.5 bar; pattern air pressure of 1.4 - 1.5 bar; air flow of 148 - 155 CFM; and pan speed of 11 - 14 rpm. Stability Study: Coated tablets were packed in 50 cc HDPE bottles with 38 mm CR closure along with different desiccants and oxygen scavengers as given in Table 1, induction sealed and screw-capped, then subjected to standard and accelerated storage conditions of 30°C/65% RH and 40°C/75% RH for one, three and six months. These coated tablets were evaluated for physical appearance, weight variation, loss on drying (Sartorius Moisture IR Balance, MA 35M), water activity (METER, AQUALAB 4TE), and disintegration time (Electrolab, EDI-2I) at predetermined intervals of exposure conditions.

Results: Tablets coated at 4% target weight gain (Figure 1) were smooth and uniform with no visual defects, such as cracking or peeling, indicating robust film integrity. Stability Study: Tablet formulation coated with Opadry amb II 88ZA565008 Brown and packed in an HDPE container with different functional packaging configurations remained stable when exposed to 40°C/75% RH for up to three months (Table 2). Water activity increased from an initial 0.418 aw to 0.445 - 0.476 aw across all the packaging configurations, indicating slight moisture uptake, but remaining below the critical level of degradation threshold. On the other hand, LOD (loss on drying) decreased from 10.88% to 8.66 - 9.90%, suggesting effective moisture control properties of the functional packaging, with 2 g silica gel (packet and canister) showing the lowest values. A slight increase in disintegration time was observed (from 16 min to 21 - 24 min), but well within acceptable limits for tablet performance. The study indicated a minor change in weight variation (938 - 953 mg) which was not significant.

Conclusion: The highly hygroscopic ferrous ascorbate and folic acid tablet showed improved stability when coated with Opadry amb II, a high-performance moisture barrier, and stored with functional packaging solutions. After three months at 40°C/75% RH, a minor increase in water activity (0.418 to 0.445–0.476) indicated limited moisture uptake, while reduction in LOD (10.88% to 8.66–9.90%) suggested moisture stabilization. A slight increase in disintegration time (16 to 21–24 min) indicated minimal changes in the matrix but remained within acceptable limits. These findings highlight the synergistic benefit of optimized film coating formulation with lower weight gain and functional packaging for preserving tablet integrity at accelerated stability conditions.

References: 1. Banerjee PG, Paul A, Chakraborty A, Porel A, Mallick P. Stability, characterization, and manufacturing optimization of ferrous Ascorbate: A Comprehensive Study by West Bengal Chemical Industries Ltd., Kolkata, India. International Journal of Pharmaceutical Research and Development. 2025 Jan 1;7(1):32–7.


Table 1: Functional Packaging Configurations for Stability Testing


Figure 1: Photographs of core and coated tablets


Table 2: Stability Data at 40°C/75% RH (Initial vs. 3 Months)