A study on the interaction of water and cellulose ethers using differential scanning calorimetry

McCrystal, Conor B.; Ford, James L.; Rajabi‐Siahboomi, Ali R.

doi:10.1016/s0040-6031(96)03148-6

Cited by 54 publications

(33 citation statements)

References 21 publications

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“…In the highest ionic strength medium, the amount of bound water was similar for all the formulations suggesting that the strength of the gel played an important role in the drug release pattern. The results show that the first few minutes of hydration are the most important because this period corresponds to the time when the protective gel layer is formed around the matrix [29]. Table 2 showed significant differences in the gel strengths for the tablet matrices of hydrochlorothiazide K100M matrices (ANOVA-test, P < 0.05).…”

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confidence: 93%

The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices

Asare-Addo

Conway

Larhrib

et al. 2013

Colloids and Surfaces B: Biointerfaces

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The evaluation of the effects of different media ionic strengths and pH on the release of hydrochlorothiazide, a poorly soluble drug, and diltiazem hydrochloride, a cationic and soluble drug, from a gel forming hydrophilic polymeric matrix were the objectives of this study. The drug to polymer ratio of formulated tablets was 4:1. Hydrochlorothiazide or diltiazem HCl extended release (ER) matrices containing hypromellose (hydroxypropyl methylcellulose (HPMC)) were evaluated in media with a pH range of 1.2-7.5, using an automated USP type III, Bio-Dis dissolution apparatus. The ionic strength of the media was varied over a range of 0-0.4 M to simulate the gastrointestinal fed and fasted states and various physiological pH conditions. Sodium chloride was used for ionic regulation due to its ability to salt out polymers in the midrange of the lyotropic series. The results showed that the ionic strength had a profound effect on the drug release from the diltiazem HCl K100LV matrices. The K4M, K15M and K100M tablets however withstood the effects of media ionic strength and showed a decrease in drug release to occur with an increase in ionic strength.For example, drug release after the 1 hr mark for the K100M matrices in water was 36 %.Drug release in pH 1.2 after 1 hr was 30 %. An increase of the pH 1.2 ionic strength to 0.4 M saw a reduction of drug release to 26 %. This was the general trend for the K4M and K15M matrices as well. The similarity factor f 2 was calculated using drug release in water as a reference. Despite similarity occurring for all the diltiazem HCl matrices in the pH 1.2 media (f2=64-72), increases of ionic strength at 0.2 M and 0.4 M brought about dissimilarity. The hydrochlorothiazide tablet matrices showed similarity at all the ionic strength tested for all polymers (f2= 56-81). The values of f2 however reduced with increasing ionic strengths.DSC hydration results explained the hydrochlorothiazide release from their HPMC matrices.There was an increase in bound water as ionic strengths increased. Texture analysis was employed to determine the gel strength and also to explain the drug release for the diltiazem 3 hydrochloride. This methodology can be used as a valuable tool for predicting potential ionic effects related to in vivo fed and fasted states on drug release from hydrophilic ER matrices.

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confidence: 93%

The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices

Asare-Addo

Conway

Larhrib

et al. 2013

Colloids and Surfaces B: Biointerfaces

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“…The effects of hydration on chemical, mechanical, and transport properties of traditional polymers like modified celluloses (HPMC, HPC) are well documented by pharmaceutical researchers [2,13]. Changes in moisture uptake of the polymer, leading to swelling and its eventual dissolution, have been exploited in several conventional dosage forms like controlled release tablets.…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydration on Physicochemical Properties of End-Capped PLGA

D’Souza

Dorati

DeLuca

2014

Advances in Biomaterials

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The objective of this study was to assess the physicochemical effects of hydrating a hydrophobic end-capped poly(lactide-coglycolide) (PLGA) polymer in the liquid and vapor state. PLGA RG503 polymer was incubated at 37 ∘ C in 0.5% polyvinyl alcohol (PVA) solution and at 90% RH. Samples were withdrawn at predetermined intervals and changes to polymer properties like glass transition temperature (T g ), moisture uptake, molecular weight change, and % acid number were determined using differential scanning calorimetry, Karl Fisher titrimetry, gel permeation chromatography, and acid base titrimetry, respectively. Study results showed that T g was depressed instantaneously upon hydration, indicating that bulk water acted as a plasticizer of hydrophobic end-capped PLGA. T g values decreased to levels below the incubation temperature when hydrated in 0.5% PVA solution but not in 90% RH. The drop in T g exhibited a linear relationship ( 2 > 0.99) to the amount of water uptake by the polymer; higher moisture uptake was noted with liquid water. Removal of moisture from the polymer matrix resulted in recovery of T g , only up to a period of 14 days. Presence of water in liquid or vapor form caused a reduction in molecular weight of the polymer and a corresponding increase in % acid number over the duration of the study.

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“…McCrystal et al, [15] noted that the relative amount of water in the different distinct states of the polymer was altered with the addition of drugs. The self-diffusion coefficient (SDS) of water in the pure gels of HPMC E4M and K4M showed the K4M being significantly lower than the E4M polymer.…”

Section: Introductionmentioning

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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A study on the interaction of water and cellulose ethers using differential scanning calorimetry

Cited by 54 publications

References 21 publications

The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices

The effect of pH and ionic strength of dissolution media on in-vitro release of two model drugs of different solubilities from HPMC matrices

Effect of Hydration on Physicochemical Properties of End-Capped PLGA

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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