Structure and behaviour in hydrophilic matrix sustained release dosage forms: 2. NMR-imaging studies of dimensional changes in the gel layer and core of HPMC tablets undergoing hydration

Rajabi‐Siahboomi, Ali R.; Bowtell, Richard; Mansfield, P.; Henderson, Artie; Davies, Martyn C.; Melia, Colin D.

doi:10.1016/0168-3659(94)00016-6

Cited by 159 publications

(76 citation statements)

References 11 publications

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“…In the axial parameters, for each time point the swelling was roughly the double respect to those measured in the radial direction. Such a result is consistent with the previously published paper on HPMC swelling [28,40,41].…”

Section: Tablets Swellingsupporting

confidence: 83%

Dextran and its potential use as tablet excipient

et al. 2015

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Dextrans are a class of carbohydrate polymers extensively applied in pharmaceutical applications, particularly as drug conjugate macromolecular carriers or drug delivery systems. These polysaccharides enable the stability of the therapeutics to be improved and for them to be delivered in a controlled manner, via either the parenteral and oral routes. In the latter case, due to their gel forming ability they may have potential as hydrophilic matrix tablets for sustained drug release.In this paper, we investigated the behaviour of different molecular weight (1, 40, 500 and 2300 kDa) dextrans as tabletting excipients. Powder particle size and hygroscopic studies have been reported, together with tabletability, tablet stability and tablet swelling. Moreover we use tramadol as model compound to evaluate the ability of dextrans to control drug dissolution. The results suggest that dextrans with lower molecular weights may be a promising excipient to be used as filler for immediate release tablets, due to their good tabletability and fast dissolution rate, while dextrans with higher molecular weights could be an efficient disintegrant due to their swelling ability.3

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Section: Tablets Swellingsupporting

confidence: 83%

Dextran and its potential use as tablet excipient

et al. 2015

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“…With these sinkers, it was possible to observe the axial and radial dimensions of the tablet at the same time. Readings of both tablet diameter and thickness were necessary since tablet swelling was more extensive in the axial direction than in the radial direction, which is in accordance with Rajabi Siahboomi et al (18). Throughout the experiment (and during the tablet weighing process) it was necessary to prevent translocation of the tablets (within the sinkers) closer to the bottom of the vessel or away from the strictly vertical position, as this could affect measurements.…”

Section: Evaluation Of Swelling Using a Camera Systemsupporting

confidence: 48%

Applicability of Bottom-View Cameras for Evaluation of Tablet Performance During Dissolution Testing

Felicijan¹,

Krese²,

Mrhar³

et al. 2016

Dissolution Technol.

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Visualization techniques are frequently used to provide additional information on dissolution processes. The camera system used here, placed underneath the dissolution bath, enabled a bottom view into each separate vessel with the possibility for continuous video recording throughout dissolution testing. Drug release and swelling of hydroxypropyl methylcellulose (HPMC) matrix tablets containing either diclofenac sodium or paracetamol were simultaneously evaluated in a series of media with pH values of 3.0 to 7.5. Swelling of HPMC tablets was studied using two methods: evaluation of the relative change in tablet volume using the camera system and evaluation of relative change in tablet mass based on tablet weighing. The correlation between evaluated parameters in the two methods was high at all pH values for the tablets studied. Swelling of diclofenac sodium tablets was lowest at pH 3, highest at pH 4, and then decreased with the increasing pH of the medium. In contrast to the swelling results, drug release from diclofenac sodium tablets increased with increasing pH of the medium. At lower media pH values (i.e., 3.0, 4.0, and 5.0), the surface of the swelled layer appeared completely white and nontransparent, whereas at higher pH values, a transparent gel layer was clearly seen using the camera system. It is presumed that because of its low solubility, diclofenac precipitated as an acid on the tablet surface at lower pH values and was seen as a white swelled layer. For paracetamol tablets, drug release and swelling were pH independent, and a gel layer was clearly seen in all media tested (pH 3.0, 5.0, and 7.0). Thus, for HPMC tablets containing diclofenac sodium, the use of cameras provided additional information on the drug release and swelling process.

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“…It was also observed that the drug release patterns for the two polymers, HPMC E4M and K4M were very different despite having similar viscosities as evident in Figure 4. As a result of HPMC K polymers having the highest ratio of hydroxypropoxyl to methoxyl substitution, gelation occurs quickly compared to other HPMC polymer grades [16,28]. Hydration and thus gelation could also have happened quickly for the HPMC K4M tablet formulation because of its higher irregularity and roughness as compared to the HPMC E4M that increases its surface area (supplementary materials Figure S1) in the hydration medium.…”

Section: Effect Of Ph and Agitationmentioning

confidence: 99%

The influence of agitation sequence and ionic strength on in vitro drug release from hypromellose (E4M and K4M) ER matrices—The use of the USP III apparatus

Asare-Addo

Kaialy

Levina³

et al. 2013

Colloids and Surfaces B: Biointerfaces

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Theophylline extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC) E4M and K4M were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The objectives of this study were to evaluate the effects of systematic agitation, ionic strength and pH on the release of theophylline from the gel forming hydrophilic polymeric matrices with different methoxyl substitution levels. Tribo-electric charging of hypromellose, theophylline and their formulated blends containing E4M and K4M grades has been characterised, along with quantitative observations of flow, compression behaviour and particle morphology.Agitations were studied at 5, 10, 15, 20, 25, 30 dips per minute (dpm) and also in the ascending and descending order in the dissolution vials. The ionic concentration strength of the media was also varied over a range of 0-0.4 M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. To study the effect of ionic strength on the hydrophilic matrices, agitation was set at 20 dpm. The charge results on individual components imply that the positively charged particles have coupled with the negatively charged particles to form a stable ordered mixture which is believed to result in a more homogeneous and stable system. The particle shape analysis showed the HPMC K4M polymer to have a more irregular morphology and a rougher surface texture in comparison to the HPMC E4M polymer, possibly a contributory factor to the gelation process. The results showed gelation occurred quicker for the K4M tablet matrices. Drug release increased with increased agitation. This was more pronounced for the E4M tablet matrices. The ionic strength also had more of an effect on the drug release from the E4M matrices. The experiments highlighted the resilience of the K4M matrices in comparison with the E4M matrices. The results thus show that despite similar viscosities of E4M and K4M, the methoxyl substitution makes a difference to their control of drug release and as such care and 3 consideration should be given to the choice of polymer used for extended release. The use of systematic change of agitation method and ionic strength may indicate potential fed and fasted effects on drug release from hydrophilic matrices.

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Structure and behaviour in hydrophilic matrix sustained release dosage forms: 2. NMR-imaging studies of dimensional changes in the gel layer and core of HPMC tablets undergoing hydration

Cited by 159 publications

References 11 publications

Dextran and its potential use as tablet excipient

Dextran and its potential use as tablet excipient

Applicability of Bottom-View Cameras for Evaluation of Tablet Performance During Dissolution Testing

The influence of agitation sequence and ionic strength on in vitro drug release from hypromellose (E4M and K4M) ER matrices—The use of the USP III apparatus

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