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Tablets & Capsules July 2019 25 have most often been used for taste masking oral sus- tained-release dosage forms [8]. This article describes a study in which researchers demonstrated how to taste mask ODT formulations by coating the API with an ECD polymer prior to tableting. This method of taste masking works by physically trap- ping the porous powder in the thin, hydrophobic ECD matrix backbone, which masks the API's bitter taste. The hydrophobicity of ECD can then be reduced by increas- ing its porosity via a suitable pore former, such as polyvi- nyl alcohol-polyethylene glycol graft copolymer. The coating can also help prevent gastric inactivation and hepatic metabolism of the API. The researchers chose paracetamol as a model API because of its high bitterness and ease of availability and handling. For the ECD polymer, they chose DuPont's Aquacoat ECD, which does not contain any plasticizer, so it provides formulation flexibility. By varying the sol- ids content of the coating formulation and combining the ECD with different plasticizers, such as triethyl citrate (TEC) or dibutyl sebacate (DBS), formulators can opti- mize the tasting masking for the ODT dosage form. Because DBS provides improved film performance, quick coalescence, and improved taste perception, it is an ideal plasticizer for preparing an ECD-based dispersion for taste-masking purposes. Coating the API The researchers first prepared the coating dispersion by blending the ECD with the DBS plasticizer for a mini- mum of six hours to ensure homogeneity. A 10 percent w/w aqueous solution of polyvinyl alcohol-polyethylene glycol graft copolymer (Kollicoat IR) was added to the ECD dispersion to function as a pore former, and the dis- persion was stirred for an additional 30 minutes. For the coating trials, the researchers chose a parac- etamol dose that was equivalent to a common clinical dose. As shown in Figure 1, they prepared the ECD and DBS coating dispersion (25 percent of EC solids) in a flu- Orally disintegrating tablets The ODT is a patient-friendly drug delivery solution that's quickly rising in popularity because of its ease of administration, accurate dosing, and simple storage requirements. The global ODT market is predicted to expand at a compound annual growth rate of 11.5 per- cent, from $11.4 billion in 2017 to $27 billion by the end of 2025 [4]. Unlike other drug delivery systems and conventional immediate-release solid dosage forms, ODTs disintegrate in the mouth within 5 to 30 seconds without chewing or requiring water. ODTs are popular with hospitals and healthcare providers because they yield improved com- pliance, particularly for patients whose swallowing reflex is compromised, which is estimated to be up to 25 per- cent of hospitalized patients [5,6]. ODTs have also been widely supported in the pediat- ric realm, as the platform combines the administration flexibility of a solid dosage form with the swallowability of a liquid dosage form [7]. In addition to disintegration time, an ODT's organo- leptic properties (taste, aftertaste, and mouthfeel) are crit- ical attributes because they impact patient acceptance and overall medication adherence. Since most APIs are bitter, sour, metallic, or otherwise unpleasant tasting, the API in an ODT must be completely taste masked while the tablet disintegrates, especially since the ODT remains in the mouth longer than other SODFs. Taste masking ODTs In recent decades, the pharmaceutical industry has invested heavily in new technologies and made great strides its ability to mask unpleasant tastes and odors. As a result, formulators have a broad range of format options and can now develop taste-masked drug products in the form of granules, films, tablets, and more. One technology that is widely used for taste masking is the aqueous ethylcellulose dispersion (ECD). ECD polymers have been gaining popularity since 1958 but Figure 1 Preparation of ECD dispersion and coating of paracetamol by fluid-bed processor (FBP) ECD DBS Mixing (6 hours) Preparing the dispersion (25 percent solid based on EC solids) Mixing (30 minutes) PVA-PEG copolymer Adding the pore former FBP (top spray) Coating the API Curing the API granules in a tray dryer