Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers

Silicone elastomers based on polydimethylsiloxane are biocompatible and non-biodegradable thermosetting polymers used in various drug delivery applications, including subdermal implants, vaginal rings, and intrauterine devices. Without exception, all marketed silicone elastomer drug delivery product...

Full description

Saved in:
Bibliographic Details
Main Authors: Xin Shen, Xinyu Zhao, Clare F. McCoy, Yahya H. Dallal Bashi, Peter Boyd, R. Karl Malcolm
Format: Article
Language:English
Published: Taylor & Francis Group 2025-12-01
Series:Drug Delivery
Subjects:
Online Access:https://www.tandfonline.com/doi/10.1080/10717544.2025.2545515
Tags: Add Tag
No Tags, Be the first to tag this record!
_version_ 1849229959158038528
author Xin Shen
Xinyu Zhao
Clare F. McCoy
Yahya H. Dallal Bashi
Peter Boyd
R. Karl Malcolm
author_facet Xin Shen
Xinyu Zhao
Clare F. McCoy
Yahya H. Dallal Bashi
Peter Boyd
R. Karl Malcolm
author_sort Xin Shen
collection DOAJ
description Silicone elastomers based on polydimethylsiloxane are biocompatible and non-biodegradable thermosetting polymers used in various drug delivery applications, including subdermal implants, vaginal rings, and intrauterine devices. Without exception, all marketed silicone elastomer drug delivery products provide sustained or controlled release of highly hydrophobic small drug molecules, since drug solubility in the silicone matrix is a prerequisite for molecular diffusion and release. We are interested in developing multipurpose silicone elastomer vaginal rings for local administration of metal ions—such as copper and zinc—for non-hormonal contraception and antimicrobial therapy. However, sustained/controlled release of metal ions from silicone elastomers containing metal nanopowders or metal salts is challenging due to their limited solubility in silicone. In this study, we assess the potential for enhancing the release of copper or zinc ions from silicone elastomer devices by co-formulating copper nanopowder, zinc nanopowder, copper sulfate, or zinc acetate with four common pharmaceutical excipients—gelatin, polyvinylpyrrolidone, sucrose, and hydroxypropyl methylcellulose. The study demonstrates that (i) copper/zinc nanopowders and salts can be successfully incorporated into addition-cure silicone elastomers, (ii) in vitro release of Cu2+/Zn2 ions from silicone elastomers loaded with divalent salts was ∼100 times greater compared to nanopowders; (iii) incorporation of gelatin, polyvinylpyrrolidone, sucrose and hydroxypropyl methylcellulose significantly enhanced the release of Cu2+/Zn2+ ions (up to ∼30-fold), and (iv) enhanced release was due to water absorption into the silicone elastomer devices, causing swelling of the devices to an extent proportional to the excipient loading.
format Article
id doaj-art-9beedab72bfa4b9b9ce8434d0fed62d9
institution Kabale University
issn 1071-7544
1521-0464
language English
publishDate 2025-12-01
publisher Taylor & Francis Group
record_format Article
series Drug Delivery
spelling doaj-art-9beedab72bfa4b9b9ce8434d0fed62d92025-08-21T13:08:36ZengTaylor & Francis GroupDrug Delivery1071-75441521-04642025-12-0132110.1080/10717544.2025.2545515Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomersXin Shen0Xinyu Zhao1Clare F. McCoy2Yahya H. Dallal Bashi3Peter Boyd4R. Karl Malcolm5School of Pharmacy, Queen’s University Belfast, Belfast, UKSchool of Pharmacy, Queen’s University Belfast, Belfast, UKSchool of Pharmacy, Queen’s University Belfast, Belfast, UKCollege of Pharmacy, University of Sharjah, Sharjah, United Arab EmiratesSchool of Pharmacy, Queen’s University Belfast, Belfast, UKSchool of Pharmacy, Queen’s University Belfast, Belfast, UKSilicone elastomers based on polydimethylsiloxane are biocompatible and non-biodegradable thermosetting polymers used in various drug delivery applications, including subdermal implants, vaginal rings, and intrauterine devices. Without exception, all marketed silicone elastomer drug delivery products provide sustained or controlled release of highly hydrophobic small drug molecules, since drug solubility in the silicone matrix is a prerequisite for molecular diffusion and release. We are interested in developing multipurpose silicone elastomer vaginal rings for local administration of metal ions—such as copper and zinc—for non-hormonal contraception and antimicrobial therapy. However, sustained/controlled release of metal ions from silicone elastomers containing metal nanopowders or metal salts is challenging due to their limited solubility in silicone. In this study, we assess the potential for enhancing the release of copper or zinc ions from silicone elastomer devices by co-formulating copper nanopowder, zinc nanopowder, copper sulfate, or zinc acetate with four common pharmaceutical excipients—gelatin, polyvinylpyrrolidone, sucrose, and hydroxypropyl methylcellulose. The study demonstrates that (i) copper/zinc nanopowders and salts can be successfully incorporated into addition-cure silicone elastomers, (ii) in vitro release of Cu2+/Zn2 ions from silicone elastomers loaded with divalent salts was ∼100 times greater compared to nanopowders; (iii) incorporation of gelatin, polyvinylpyrrolidone, sucrose and hydroxypropyl methylcellulose significantly enhanced the release of Cu2+/Zn2+ ions (up to ∼30-fold), and (iv) enhanced release was due to water absorption into the silicone elastomer devices, causing swelling of the devices to an extent proportional to the excipient loading.https://www.tandfonline.com/doi/10.1080/10717544.2025.2545515Drug deliverygelatinpolyvinylpyrrolidonehydroxypropyl methylcellulosesucrosesilicone rubber
spellingShingle Xin Shen
Xinyu Zhao
Clare F. McCoy
Yahya H. Dallal Bashi
Peter Boyd
R. Karl Malcolm
Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
Drug Delivery
Drug delivery
gelatin
polyvinylpyrrolidone
hydroxypropyl methylcellulose
sucrose
silicone rubber
title Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
title_full Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
title_fullStr Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
title_full_unstemmed Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
title_short Use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
title_sort use of hydrophilic pharmaceutical excipients to modulate release of metal ions from silicone elastomers
topic Drug delivery
gelatin
polyvinylpyrrolidone
hydroxypropyl methylcellulose
sucrose
silicone rubber
url https://www.tandfonline.com/doi/10.1080/10717544.2025.2545515
work_keys_str_mv AT xinshen useofhydrophilicpharmaceuticalexcipientstomodulatereleaseofmetalionsfromsiliconeelastomers
AT xinyuzhao useofhydrophilicpharmaceuticalexcipientstomodulatereleaseofmetalionsfromsiliconeelastomers
AT clarefmccoy useofhydrophilicpharmaceuticalexcipientstomodulatereleaseofmetalionsfromsiliconeelastomers
AT yahyahdallalbashi useofhydrophilicpharmaceuticalexcipientstomodulatereleaseofmetalionsfromsiliconeelastomers
AT peterboyd useofhydrophilicpharmaceuticalexcipientstomodulatereleaseofmetalionsfromsiliconeelastomers
AT rkarlmalcolm useofhydrophilicpharmaceuticalexcipientstomodulatereleaseofmetalionsfromsiliconeelastomers