Applications, performance, and examples
PharmTech:
What are the applications for this excipient, how is it used to provide tastemasking, and what are some examples?
Langley:
It has wide applicability, not only in tablet coatings, but also in pellet, particle, and crystal coatings. It is useful
for orally disintegrating tablets, for tastemasking oral dispersibles, and also in granulation processes.
The recommendation of tablet-coating levels to provide tastemasking is between 2–5 mg/cm2, a little bit more is needed for moisture protection at 5–20 mg/cm2. Kollicoat Smartseal 30 D has very low water-vapor permeability. As a result, it is not plasticized by water. So, in coating,
it is necessary to add a plasticizer in order to reduce the minimum film-forming temperature (~57 °C) to an acceptable level.
Triethyl citrate and tributyl citrate are recommended for this purpose. In addition, an antioxidant, preferably butylated
hydroxy toluene (BHT, 1–2.5 % based on polymer weight) is also required in the coating formulation.
A good tastemasking polymer would show no drug release at pH 6.8 to 7.2. And this is what Kollicoat Smartseal 30 D has been
designed for. Let's compare different coating levels and the amount of drug release relative to the uncoated cores for the
bitter drug, quinine hydrochloride. At coating levels between 4 mg/cm2 and 5 mg/cm2, there is no release of the drug at pH 6.8 to 7.2 during 60 min. When you reduce the pH to 1.2, you will see complete drug
release, and this is an ideal situation for tastemasking.
PharmTech:
What are other applications of the product?
Langley:
Smartseal 30 D is also very suitable for pellet and crystal coatings. We believe that these applications increase in importance
due to the rise of innovative dosage forms, such as orally dispersible tablets. For example, caffeine pellets can be effectively
tastemasked at a coating level of 5 mg/cm2. Acetaminophen crystals are effectively tastemasked at 30 % weight gain where there is no drug release at pH 6.8 –7.2 during
120 min. Some tastemasking is achieved even as low as 7.5% weight gain. In each example, the pellet and crystal coating can
be visualized by including a pigment in the formulation. Kollicoat Smartseal 30 D has an additional benefit as it provides
gloss.
PharmTech:
How do you evaluate tastemasking performance, and what are the key characteristics to achieve tastemasking?
Langley:
Although it is good to show dissolution data, we really need to see it in reality whether you are achieving a tastemasking
effect on the tablets themselves when you take them into your mouth. Using a professional panel for tastemasking is obviously
important because they are trained to do just this exercise.
In our analysis, we [BASF] compared Kollicoat Smartseal 30D with the commercially available butylated methyl acrylate copolymer
and hydroxypropyl methylcellulose products. At different coating levels, the panelists provided their assessments of bitter
taste. For example, with the Kollicoat Smartseal 30D, at 5 mg/cm2, all the panelists reported a complete absence of bitter taste for quinine hydrochloride compared to the other materials
tested. Hence, Kollicoat Smartseal 30 D is a very effective tastemasking polymer at that coating level.
In sum, Kollicoat Smartseal 30 D has extremely low water-vapor permeability, thereby providing the opportunity for moisture
protection. It shows quick dissolution in acidic medium below pH 5.5 and a strong resistance at neutral pH. It is, therefore,
deemed highly suitable for both tastemasking and moisture-protective coatings. One other advantage is it is an aqueous-based
coating. No solvents are required. It has very low odor, and even more importantly, is not sticky, which can be a real advantage,
especially on a manufacturing scale. It enables quick and simple preparation of the coating suspension. It has low viscosity
and is easy to spray at high solids concentrations. It is effective at relatively low coating levels. Kollicoat Smartseal
30 D has been specifically designed to show exactly all of these characteristics to provide the solution the market was looking
for. The result is tastemasking and moisture protection in combination with instant release and easy and economical film coating.
For the editorial webcast, "Tastemasking in Formulation Development," see http://www.pharmtech.com/fds, or the webcast section at
http://www.PharmTech.com/webcasts.
Reference
1. "Tastemasking in Formulation Development" Webcast, Pharm. Technol. Sept. 2011, http://pharmtech.com/fds, accessed Aug. 20, 2012.
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