Functionality of Benecel K4M/Carbopol 971P NF matrices in direct compression tablets for controlled release.

The aim of this work is the assessment of the eventual enhancing effects of Carbopol 971P NF on the performance of Benecel K4M as a controlled release agent and its impact on other technological properties such as compactibility and powder flowability. The effect of Carbopol 971P NF and Benecel K4M in the performance of metronidazole tablets with controlled release was assessed using dissolution and compactibility profiles and the flowability of powders. Benecel K4M produces release profiles with an average exponent n=0.711 while Carbopol 971P NF displays average values of n=1.19. The values for tablets containing equal parts of Carbopol 971P NF and Benecel K4M was an average of n=0.947. Metronidazole tablets containing the Benecel K4M/Carbopol 971P NF blend shows a compactibility 2-3 times higher than tablets containing only Benecel K4M. Metronidazole/Benecel K4M blends flow sufficiently at all studied polymer proportions (≤ 30%) while admixtures of metronidazole/Benecel K4M with Carbopol 971P NF flow sufficiently only at polymer proportions ≤ 17%. Carbopol 971P NF enhances the overall performance of Benecel K4M in the same way as Noveon AA1 does, it reduces better the drug release and improves the compactibility, although decreases the flowability.

Influence of different types of lactose on powder flow and tablets dissolution.

The objective of this study was the evaluation of different types of lactose on the powders flow properties and dissolution of tablets of formulations with captopril and amoxicillin. Data of powders flow rate, compressibility index and dissolution profiles of tablets are presented. The powders flow rate showed higher sensitivity to small changes in their properties, compared to compressibility index. SuperTabs 21AN and 24AN flow at least 20 times faster than Lactopress and lactose NF. Lubrication increases the flow rate, maintaining the observed comparative differences. Dilution of lactoses with 50% captopril or amoxicillin reduces drastically the powder flow, producing also an equalizing effect. The greater flowability of SuperTabs, compared to other types of lactose, practically disappears. Dissolution of lubricated and unlubricated lactose tablets show a much faster dissolution of SuperTab 21AN tablets followed by Lactopress, lactose NF and SuperTab 24AN tablets. Dilution of lactoses with 50% captopril displays a quite smaller dissolution rate with a comparative similar behavior as observed before while dilution with amoxicillin show an equalizing effect of drug dissolution with minor differences between lactoses. The effect of lactose excipients on dissolution is attributed in a greater extent to mechanical properties of their tablets than to differences in solubility and dissolution.

Noveon AA1 as enhancer of HPMC as a direct compression matrix for controlled release.

This work aimed the assessment of the effect of different proportions of Noveon AA1 on performance of HPMC as a controlled release agent for direct compression tablets. The functionality of polymer blends was determined using dissolution profiles, compactibility profiles and the powders compressibility index. Ten percent HPMC allows a metronidazole release after 3 h of 85%, an exponent n=0.48 and a release constant K=6.9. The increasing polymer substitution by Noveon AA1 decreases drug dissolution up to 36%, increases the exponent to 1.0 and decreases the release constant to 0.2%. The metronidazole/HPMC blend shows a slower increasing and a lower potential of tablets compactibility (20 N) while its increasing substitution by Noveon AA1 attains faster increasing and higher potential compactibilities (39 N). The metronidazole/HPMC (90:10) blend shows a low compressibility index (14%) that increases up to 33.2% with increasing Noveon AA1 proportions. Noveon AA1 proportions ≤ 5% display good/passable powder flowabilities. Noveon AA1 enhances the overall controlled release performance of HPMC, inducing zero order release patterns without lag or burst effects and reducing drug release more efficiently. Noveon AA1 also improves the compactibility of metronidazole/HPMC blends, however, decreases their flowability; flowability is acceptable only at lesser polymer proportions.