Minitablets Coated in a Solid-Wall Pan for Theophylline Sustained-Release Capsules - Pharmaceutical Technology

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Minitablets Coated in a Solid-Wall Pan for Theophylline Sustained-Release Capsules
The authors describe an alternative approach to compressing and coating minitablets for use in a sustained-release, solid oral-dosage form. This article is part of a special Drug Delivery issue.

Pharmaceutical Technology
pp. s38-s42

Table IV: Characteristics of the four formulations used in minitablet compression.
Dissolution tests were then performed on mT4 uncoated and mT4 coated with formula A and formula B at two different coating amounts. These tests aimed to confirm the absence of coating defects such as cracking and to evaluate the effect of the amount of polymer on drug release. In addition, the equivalence of both coating formulations was checked. As expected, Figure 5 shows that the uncoated mT4 released 100% of the active ingredient in less than 90 minutes, clearly demonstrating the need for film coating to achieve a sustained release. The good coating quality was demonstrated by obtaining a sustained release behavior using both formulas even at the lowest polymer amount. Furthermore, the release data showed the influence of the coating level on TH release. The dissolution profiles of both formulas at the same coating levels were not significantly different, which is evidence that the ready-to-use system is equivalent to the traditional one.

Finally, coated minitablets were filled into hard gelatine capsules size 0. The maximum speed achieved for the production was 12000 capsules/hour, representing 80% of the highest speed of the capsule filler when dosing standard volumetric pellets. Production was successfully carried out for 2 h without any rejected capsules, thereby confirming the system reliability.


Minitablets containing a high amount of TH, low friability, and high crushing strength were obtained by direct compression and then coated in a solid-wall pan. The use of a ready-to-mix pigment dispersion represents an interesting alternative to shorten coating-suspension-preparation time when compared with traditional formulations. The coated minitablets were then successfully filled into hard gelatine capsules. In conclusion, the results demonstrated that the innovative approach used in this study could be potentially useful for the industrial-scale manufacture of a sustained-release, oral-solid-dosage form.


The authors would like to thank Rosamund Cervo for her kind support in checking the English.

Caterina Funaro* is a process laboratory manager, and Giusi Mondelli is a process specialist at IMA Active Division, Via 1 Maggio, 14 40064 Ozzano dell' Emilia, Bologna, Italy, tel. 0039 0516 5141 11, fax 0039 0516 514287,
. Nadia Passerini and Beatrice Albertini are both assistant professors in the Department of Pharmaceutical Sciences, University of Bologna, Italy.

*To whom all correspondence should be addressed.


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2. T. Riis et al., Eur. J. Pharm. Biopharm. 65 (1) 78–84 (2007).

3. C. M. Lopes et al., Drug. Dev. Ind. Pharm. 32 (1) 95–106. (2006).

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5. A. Spadoni, Pharm. Proc. published online (Jan. 2001),, accessed Oct. 22, 2010.

6. M. Ishida et al., Int. J. Pharm, 359 (1–2), 46–52 (2008).

7. L. Ho et al., J. Control. Rel. 127 (1), 79–87 (2008).


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