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The long-term release of antibiotics from monolithic nonporous polymer implants for use as tympanostomy tubes

The long-term release of antibiotics from monolithic nonporous polymer implants for use as tympanostomy tubes
The long-term release of antibiotics from monolithic nonporous polymer implants for use as tympanostomy tubes
A technology is elaborated for the fabrication of a novel tympanostomy tube (TT) from solidified polymer melts (Elvax and polyurethane) and antibiotics (ciprofloxacin and (+)- usnic acid) for insertion into the tympanic membrane (ear drum) according to the established surgical procedure. The long-term in vitro release kinetics of the antibiotics into liquid water was assessed using standard methods. The measured kinetic curves revealed two stages of antibiotic release into finite space. During the first stage (fast), the release rate was almost invariant and was determined by diffusion through the steady diffusion layer formed due to solution agitation. In this first stage, the influence of the initial internal transport was weak because it takes place at a negligibly small distance from the interface, and therefore, at a negligible concentration drop. After the antibiotic concentration decreased within the much broader layer of the matrix near the interface, internal transport became important. This manifested itself as the second stage in the measured kinetics of release curves, which were characterized by a gradual decrease in rate. The minimum inhibition concentrations of three antibiotics/antimicrobial compounds for four bacterial species were measured. The first stage of fast release from the polymer implant lasted 6 days at a polymer loading by ciprofloxacin (0.03 g/cm3), and this was sufficient to prevent biofilm formation on the surface of the implant material. The measured kinetic curves of drug release showed a more rapid decrease in the release rate compared to the Higuchi approximation. Comparison with existing theories, which account for the finite rate of drug dissolution, showed that this may explain the observed deviation from the diffusion-controlled Higuchi model. Large dimensions of drug particles and their aggregation retarded the dissolution stage, and consequently, the release rate. Melt blending was found to cause drug particle aggregation within the polymer matrices, which was confirmed by microscopic reexamination of the polymer implant materials
drug release, extrusion, drug particle aggregation, drug dissolution rate, drug particle size, otitis media, tympanostomy tube, monolithic nonporous polymer implants
0927-7757
331-337
Labib, Mohamed E.
a2d52c8a-3305-44cf-803b-78239b1cb8b5
Brumlik, Charles J.
82068a26-8dd7-4200-9619-5ae893839d15
Stoodley, Paul
08614665-92a9-4466-806e-20c6daeb483f
Dukhin, Stanislav S.
b8d6e5d5-6db6-49a7-a5d7-5e3c6549fc61
Davidson, Theodore
92784cae-942a-431c-b559-141f42371e02
Tabani, Yacoob
4729011e-e8ac-4d73-b856-08d5e06cbffc
Labib, Mohamed E.
a2d52c8a-3305-44cf-803b-78239b1cb8b5
Brumlik, Charles J.
82068a26-8dd7-4200-9619-5ae893839d15
Stoodley, Paul
08614665-92a9-4466-806e-20c6daeb483f
Dukhin, Stanislav S.
b8d6e5d5-6db6-49a7-a5d7-5e3c6549fc61
Davidson, Theodore
92784cae-942a-431c-b559-141f42371e02
Tabani, Yacoob
4729011e-e8ac-4d73-b856-08d5e06cbffc

Labib, Mohamed E., Brumlik, Charles J., Stoodley, Paul, Dukhin, Stanislav S., Davidson, Theodore and Tabani, Yacoob (2010) The long-term release of antibiotics from monolithic nonporous polymer implants for use as tympanostomy tubes. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 354 (1-3), 331-337. (doi:10.1016/j.colsurfa.2009.10.028).

Record type: Article

Abstract

A technology is elaborated for the fabrication of a novel tympanostomy tube (TT) from solidified polymer melts (Elvax and polyurethane) and antibiotics (ciprofloxacin and (+)- usnic acid) for insertion into the tympanic membrane (ear drum) according to the established surgical procedure. The long-term in vitro release kinetics of the antibiotics into liquid water was assessed using standard methods. The measured kinetic curves revealed two stages of antibiotic release into finite space. During the first stage (fast), the release rate was almost invariant and was determined by diffusion through the steady diffusion layer formed due to solution agitation. In this first stage, the influence of the initial internal transport was weak because it takes place at a negligibly small distance from the interface, and therefore, at a negligible concentration drop. After the antibiotic concentration decreased within the much broader layer of the matrix near the interface, internal transport became important. This manifested itself as the second stage in the measured kinetics of release curves, which were characterized by a gradual decrease in rate. The minimum inhibition concentrations of three antibiotics/antimicrobial compounds for four bacterial species were measured. The first stage of fast release from the polymer implant lasted 6 days at a polymer loading by ciprofloxacin (0.03 g/cm3), and this was sufficient to prevent biofilm formation on the surface of the implant material. The measured kinetic curves of drug release showed a more rapid decrease in the release rate compared to the Higuchi approximation. Comparison with existing theories, which account for the finite rate of drug dissolution, showed that this may explain the observed deviation from the diffusion-controlled Higuchi model. Large dimensions of drug particles and their aggregation retarded the dissolution stage, and consequently, the release rate. Melt blending was found to cause drug particle aggregation within the polymer matrices, which was confirmed by microscopic reexamination of the polymer implant materials

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More information

Published date: February 2010
Additional Information: The National Centre for Advanced Tribology at Southampton (nCATS)
Keywords: drug release, extrusion, drug particle aggregation, drug dissolution rate, drug particle size, otitis media, tympanostomy tube, monolithic nonporous polymer implants
Organisations: Engineering Sciences

Identifiers

Local EPrints ID: 72105
URI: http://eprints.soton.ac.uk/id/eprint/72105
ISSN: 0927-7757
PURE UUID: 0c49cb71-b4a0-44e7-8379-7277f675660e
ORCID for Paul Stoodley: ORCID iD orcid.org/0000-0001-6069-273X

Catalogue record

Date deposited: 21 Jan 2010
Last modified: 14 Mar 2024 02:55

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Contributors

Author: Mohamed E. Labib
Author: Charles J. Brumlik
Author: Paul Stoodley ORCID iD
Author: Stanislav S. Dukhin
Author: Theodore Davidson
Author: Yacoob Tabani

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