Figure 5 shows the overlay plot. Superimposing the contour of individual responses to achieve a region that satisfies the
constraints for all the attributes generated the overlay plot. All combinations falling in the yellow region satisfy the selected
constraints. Batch F3 falls is this region and therefore was selected as the best of the batches prepared according to the
23 factorial design. Tablets containing 30% acetaminophen and 70% agglomerates of batch F3 had friability values <1% and disintegration
time <15 min. The in vitro dissolution study indicated that more than 90% of the drug released in 30 min, indicating the noninterference of the filler–binder
with drug release.
Figure 5, (All figures are courtesy of the authors.)
Validation of the evolved mathematical models.
To validate the evolved mathematical models, two check points were selected. Two batches CH1 and CH2 were prepared and evaluated
(see Table VI). To further validate the model an optimum batch OPT was located using grid analysis where angle of repose was
23°, Carr's index was 12, crushing strength of blank tablet was 110 N, and crushing strength of acetaminophen containing tablets
was 51 N. Close agreement was found between observed and predicted values, thus strengthening the predictability of the mathematical
Table VI: Validation of the evolved mathematical models.
Various binders were screened for their effect on agglomerates of lactose and dibasic calcium phosphate diydrate. Each binder
shows marked effect on various aspects of the agglomerate. If HPMC, starch, and silicon dioxide enhance the flow properties,
acacia has a negative effect on these properties. PEG increases the crushing strength of blank tablets. Guar gum increased
the hardness of tablets containing acetaminophen. Combination of binders for agglomeration of lactose and DCP to yield a directly
compressible product with desirable attributes could be isolated using the 23 factorial design.
Anita Lalwani* is an assistant professor in the Department of Pharmaceutics at the K.B. Institute of Pharmaceutical Education and Research,
Sector-23, Gh-6 Road, Gandhinagar-382023, Gujarat, India, tel. 91 98983 20018, email@example.com
Jolly Parikh is an assistant professor in the Department of Pharmaceutics at A.R. College of Pharmacy and G.H. Patel Institute of Pharmacy,
Vallabh Vidyanagar-388 120, Gujarat, India.
*To whom all correspondence should be addressed.
What would you do differently? Email your thoughts about this paper to firstname.lastname@example.org
and we may post them to the site.
1. G.K. Bolhuis and N.A. Armstrong, "Excipients for Direct Compaction: An Update," Pharm. Dev. Technol.
11 (1), 111?124 (2006).
2. M.C. Gohel and P.D. Jogani,"A Review of Coprocessed Directly Compressible Excipients," J. Pharm. Pharma. Sci.
8 (1), 76–93 (2005).
3. R. Linden et al., "Response Surface Analysis Applied to the Preparation of Tablets Containing a High Concentration of
Vegetable Spray-Dried Extract," Drug Dev. Ind. Pharm.
26 (4), 441–446 (2000).
4. Y.K. Agrawal and K. Prakasam, "Effect of Binders on Sulfamethoxazole Tablets," J. Pharm. Sci.
77 (10), 885–888 (1988).
5. H.M. Elsabbagh, A.M. Sakr, and S.E. Abd-Elhadi, "Effect of Guar Gum on the Dissolution Rate of Ephedrine Hydrochloride
and Sulphadimidine Tablets," Pharmazie
33 (11), 730–731 (1978).
6. N. Yaksel, A. Karataay, and T. Baykara, "Comparative Evaluation of Granules Made with Different Binders by a Fluidized
Bed Method," Drug Dev. Ind. Pharm.
29 (4), 387-395 (2003).