(T1530-01-05) Pectin as a Natural Tablet Coating Alternative

Purpose: Tablets are the most common dosage form for pharmaceutical and nutraceutical products. Most tablets utilize a coating to improve aesthetics, mask bitter taste from actives, and make the tablets easier to swallow. While HPMC is commonly used in the industry for tablet coatings, in the dietary supplement market, there is a trend towards cleaner label and more natural ingredients. Pectin as a material is very well accepted by consumers and has proven excellent as a coating for immediate release tablets. This would allow for a clean label coating technology to meet consumer demand in the dietary supplement market.

Methods: Pectin and HPMC coating solutions were prepared at 5 wt% solids with the addition of 0.3% plasticizer, either PEG 400 or glycerin. 800 mg tablet cores containing 25% theophylline, were coated with the polymer solutions using a Freund-Vector LDCS Hi-coater equipped with a 0.7 mm nozzle positioned approximately 7 inches from the bed. The solution was sprayed at 3 g/min while the pan was rotating at 20 rpm. The resulting tablets were evenly coated to a weight gain of 2.5-3% with minimal overspray evident in the pan. Dissolution testing and friability was tested on the coated tablets to look at drug release rate and coating durability respectively. The dissolution was carried out in a standard USP II setup with 900 mL of DI water as the media. The media was stirred with paddles at 50 rpm, and the concentration of theophylline was monitored by UV/vis at 272 nm over the course of 4 hours. Friability testing was conducted on 20 tablets at a time where the initial weight of the tablets was recorded, and the tablets were reweighed at two-minute intervals up to 8 minutes. Tablets were de-dusted at each interval prior to weighing to remove any coating material that may have chipped off during the test.

Results: HPMC is the industry standard for tablet coatings, so pectin coatings were compared for their performance relative to HPMC. Processing equivalent solutions of pectin and HPMC (5 wt% solutions) led to equivalent coating performance, where the distribution of the coating was evenly applied to the tablet cores with minimal overspray. No sticking of the tablets to themselves or the pan was observed for either coating system. Tablets were coated to a standard 3% weight gain, which was easily achieved. The finished coated tablets, both pectin and HPMC, visually had a smooth and shiny appearance with no distinguishable differences. To confirm the immediate release profile of the coatings, dissolution testing was performed, and the results are shown in Figure 1. Uncoated tablets show immediate release of theophylline where 90% of the drug was released within the first 15 minutes of the dissolution test. With coated tablets, a 5-10 minute lag time in drug release is expected while the coating dissolves. For HPMC coated tablets, a small delay in release onset was observed, but over 80% of theophylline was still released in the first 15 minutes. For pectin coated tablets, a slightly longer delay in release onset was observed where it took 20 minutes to reach about 80% theophylline release. According to the USP < 2040 > for dietary supplement tablets, coated tablets must fully disintegrate within 30 minutes, so the pectin tablets still met the requirements for immediate release. The relative strength of the coating films was also analyzed for mechanical strength and elasticity. Having sufficient mechanical strength or integrity of the coating is important so that the tablets are not damaged during transport and general use by the consumer. Figure 2 shows film puncture data comparing HPMC and pectin films. In general, the pectin films showed slightly higher puncture strength than the HPMC films, but with the same elasticity.

Conclusion: Pectin coated tablets were compared to HPMC coated tablets for their physical properties and drug release profile. Pectin tablets showed a slightly longer delay in onset of drug release compared to HPMC coatings, but still met requirements for an immediate release dosage form. The physical properties of the pectin films were slightly stronger when compared to HPMC, but with the same elasticity indicating the films should have good performance in the coating process. Using pectin for tablet coatings offers a label friendly alternative to HPMC, allowing supplement brand owners to satisfy consumer demands.

Dissolution profile showing IR of HPMC and pectin coated tablets



Physical properties of HPMC vs. pectin films