Diffusion and Concentration Profiles of Drugs in Gels

Upadrashta, Sathyanarayana M.; Haglund, Bert O.; Sundelöf, Lars‐Olof

doi:10.1002/jps.2600821106

Cited by 28 publications

(16 citation statements)

References 9 publications

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“…The data seem to agree with Arrhenius kinetics with an activation energy on the order of 25 to 30 kJ/mole. The activation energy for the diffusion of small molecules is generally between 18 and 20 kJ/mole [19,24,25]. These results indicate that the microviscosity of the gel was higher than that of the dilute aqueous solution and that it plays an important role in the transport of paracetamol through the chitosan hydrogel.…”

Section: Resultsmentioning

confidence: 87%

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Diffusion coefficient of paracetamol in a chitosan hydrogel

2004

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Section: Resultsmentioning

confidence: 87%

“…The measured values are on the order of 4.54Â10 À14 m 2 /s for black dye (MW=592) and 4.48Â10 À15 m 2 /s for green die (MW=6000), respectively. Extrapolating this diffusion coefficient to a molar mass of paracetamol, using the relationship provided by Burnette [19] between diffusion coefficient D and molecular weight M w :…”

Section: Resultsmentioning

confidence: 99%

Diffusion coefficient of paracetamol in a chitosan hydrogel

2004

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“…18 This expression has often been used to measure drug diffusivities in gels 19 and is valid when the experiment duration is much shorter than tissue equilibration time t eq , as was the case here. As a rough guide, the order of magnitude relation t eq ‫ف‬L 2 /D yields an estimated t eq of 3…”

Section: Measurements Of Transmural and Planar Diffusionmentioning

confidence: 91%

Arterial Ultrastructure Influences Transport of Locally Delivered Drugs

Hwang

Edelman

2002

Circulation Research

110

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Abstract-An incomplete understanding of the transport forces and local tissue structures that modulate drug distribution has hampered local pharmacotherapies in many organ systems. These issues are especially relevant to arteries, where stent-based delivery allows fine control of locally directed drug release. Local delivery produces tremendous drug concentration gradients and although these are in part derived from transport forces, differences in deposition from tissue to tissue imply that tissue ultrastructure also plays an important role. We measured the equilibrium drug uptake and the penetration and diffusivity of dextrans (a model hydrophilic drug similar to heparin) and albumin in orthogonal planes in arteries explanted from different vascular beds. We found significant variations in drug distribution with geometric orientation and arterial connective tissue content. Drug diffusivities parallel to the connective tissue sheaths were one to two orders of magnitude greater than across these sheaths. This diffusivity difference remained relatively constant for drugs up to 70 kDa before decreasing for larger drugs. Drugs also distributed better into elastic arteries, especially at lower molecular weights, with almost 66% greater transfer into the thoracic aorta than into the carotid artery. Arterial drug transport is thus highly anisotropic and dependent on arterial tissue content.

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“…For example, it is an important analgesic drug and antipyretic agent, and in combination with opioid analgesics, it can also be used in the management of more severe pain such as post surgical pain, and provide palliative care in advanced cancer patients [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, diffusion coefficients of paracetamol in aqueous solutions and their dependence on media composition (e.g., pH, ionic strength and metal ions) have been poorly characterized, even though these transport parameters are necessary to obtain a satisfactory understanding of its important pharmacy function. A few diffusion coefficients of paracetamol in different systems (e.g., in hydrated alginate and alginic acid gels [3], in macroporous chitosan hydrogels using a diaphragm cell technique [4], in 1% (w/w) agarose gels at different temperatures [5], and through gastric mucus, where it was shown that mucus acts as a passive barrier in the case of paracetamol diffusion [6]) have been reported but, as far as the authors know, after careful literature search, no data are available for aqueous systems involving this drug at T = 298.15 K.…”

Section: Introductionmentioning

confidence: 99%