Injectable bulking agents may be used to seal isolated/multiple defects in the internal anal sphincter. Several agents have been used historically, including silicon (PTQ®) and Pyrolytic carbon-coated beads (Durasphere®).
PTQ® (Uroplasty Ltd., Geleen, The Netherlands) is a polydimethylsiloxane elastomer suspended in a bioexcretable hydrogel carrier of polyvinylpyrrolidone. It contains solid textured silicone particles that allows deposition of host collagen. It can be injected directly into the sphincteric defect and also into the intersphincteric plane. Its mechanism of action is thought to be directly due to the bulking effect of silicone injection, as well as a delayed effect due to the scaring due to fibrosis that results over time. The success rates are variable ranging from 20% to 70%.
Durasphere® is another injectable material that contains carbon-coated zirconium oxide beads. Unlike PTQ®, they are not biodegradable, and its injection should be in the submucosal plane. It has a lower success rate as well as higher morbidity including rectal pain, erosion, arthritis and hypersensitivity reaction.
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- Tjandra, J.J., M.K. Chan, and H.C. Yeh, Injectable silicone biomaterial (PTQ) is more effective than carbon-coated beads (Durasphere) in treating passive faecal incontinence–a randomized trial. Colorectal Dis, 2009. 11(4): p. 382-9.