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Oscillating Aqueous Gels as Drug Delivery Systems

Huang, Tien-Lu
http://rave.ohiolink.edu/etdc/view?acc_num=osu1366066532

Abstract Details

2013, Doctor of Philosophy, Ohio State University, Pharmacy.
Aqueous liquid crystal gels formed by surfactant/cosurfactant/oil/water systems have been studied as potential novel controlled release drug delivery systems. They possess a unique oscillating property that was evaluated as a means of controlling drug release dependent upon intentional structural modifications of the systems. Based on the phase behavior of various quaternary compositions of nonionic surfactant and cosurfactant with oil and water, gel systems with suitable oscillating properties and homogenous physical appearances were selected as prototypes for characterization of drug release. Model "non-oscillating" gel systems were also formulated with the same constituents and similar weight proportions to act as controls. Lidocaine and lidocaine/prilocaine eutectic mixture were selected as the model drug components. Optical and polarized light microscopy images were used to determine the structure and texture of each aqueous gel, and they have indicated cubic liquid crystal structures for the oscillating systems. To further characterize the microstructure and rheological properties of the prototype oscillating gels, viscosity measurements, dynamic light scattering, micro-CT, acoustic microscopy, and solid-state NMR techniques were used. Acoustic measurements were made to study the sound and resonance characteristics of the gels using a self-designed sound-detecting apparatus with a virtual digital oscilloscope on a computer. Sonograms of the frequencies and amplitudes of gel oscillation were captured and recorded on the virtual oscilloscope. The time domain waveforms exhibited Bessel-type functions with damping acoustic waves. Mechanical vibration and resonation of sound by the prototype oscillating gels was independent of the presence of the model drugs, and the characteristic frequencies of the gels examined were about 6 kHz. In addition to mechanical means, continuous and pulsed electrical currents were used in an attempt to activate the gels. Studies of the diffusion of lidocaine-H+ from the prototype gel systems were performed under both static and dynamic conditions; drug concentrations were analyzed by HPLC. To enhance diffusion, a rotating disc spindle or ultrasound were used to mechanically disrupt the structure of the gels, and drug release profiles resulting from the different perturbation methods were evaluated. Drug release and physicochemical characteristics of oscillating gels and non-oscillating gels were also compared. The release of lidocaine was slow, which was apparently due to the highly structured liquid crystal phases, setting up barriers to diffusion. Drug release was influenced by the apparent viscous nature of the systems, stirring speed in the receiver compartment of a Franz diffusion cell, ambient temperature, and the degree of perturbation of the gel structure. Higher amounts of drug were released from oscillating gels than from non-oscillating gels upon ultrasonic perturbation of the gel structure. Overall, data indicate that oscillating gels appeared to be more subject to mechanical perturbation than non-oscillating gels, likely due to the unique three-dimensional liquid crystal structure of the oscillating systems. Diffusional drug release can be facilitated when the structure of the gel is disrupted, and drug can be delivered at greater rates from a disordered oscillating gel structure than when it is at rest. Moreover, a tiered pattern as a result of on/off ultrasonic activation was shown in the drug release profiles. Therefore, oscillating gel-based drug delivery applications can be developed where on/off control of drug release is desired. These aqueous gel systems may function as potential novel drug delivery systems in devices applied to the skin or elsewhere. Since diffusion will be the main mechanism for drug release, pain, tissue damage, or irreversible alterations of skin structure could be avoided.
Sylvan Frank (Advisor)
Pharmaceuticals

Recommended Citations

Citations

  • Huang, T.-L. (2013). Oscillating Aqueous Gels as Drug Delivery Systems [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366066532

    APA Style (7th edition)

  • Huang, Tien-Lu. Oscillating Aqueous Gels as Drug Delivery Systems. 2013. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1366066532.

    MLA Style (8th edition)

  • Huang, Tien-Lu. "Oscillating Aqueous Gels as Drug Delivery Systems." Doctoral dissertation, Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1366066532

    Chicago Manual of Style (17th edition)

osu1366066532
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© 2013, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.