Pharmaceutical solid dosage forms are commonly coated to modify the release of drugs. Due to the disadvantages of coated single-unit dosage forms, such as occurrences of dose dumping and local irritation, coated multi-particulates are preferred. Coated multi-particulates can eventually be filled into capsules or compressed into tablets. The latter is more desirable as unit production costs of tablets are considerably lower and machinery is more easily available. However, compression forces can result in structural changes to the coat, affecting its function. Hence, it is important to understand the factors affecting coat damage during compression [1], [2], [3].

The objective of this project is to examine how plasticization of coatings mitigate the level of pellet coat damage in tableted multi-unit pellet system (MUPS). The method involves coating of sustained release coats of different levels of plasticizer triethyl citrate (TEC) by film casting method. The compacts were made with the coated pellets. The casted films were studied for their mechanical properties and the coated pellets for their dissolution study. The model drug chlorpheniramine maleate was loaded onto sugar coated pellets of 500–600 µm in size using HPMC, povidone and de-ionized water. The drug loaded pellets were film coated with aqueous ethyl cellulose dispersion with varying levels of TEC using precision coating unit. The coated pellets were formulated with lactose, crospovidone and magnesium stearate into compact masses, by using 15 mm flat face punches with a compression force of 10  kN. These compacted tablets of MUPS were studied for in-vitro tests like hardness, disintegration and dissolution rate. The surface morphology of the pellets was assessed by using SEM and the results were statistically analyzed by ANOVA.

The results of hardness, disintegration and dissolution were shown in Fig. 1. When the amount of TEC increased, the tablet hardness decreased which comparably produced soft and easily breakable tablets. The disintegration test shows increase in disintegration time with increased TEC concentration. A significant sustain action was observed in 2% weight gain, rather than 10% weight gain pellets. This was found to be the same in all the varying concentrations of TEC (10%, 20% and 30%) signifying that there was coat damage in 10% weight gain pellets. It can be concluded that the coated pellets could be compressed into tablets without mechanical damage to the coating membrane when additives of 2% weight gain at 10% TEC was used.

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