Six bioabsorbable polymers: In vitro acute toxicity of accumulated degradation products

Abstract

Bioabsorbable polymer implants may provide a viable alternative to metal implants for internal fracture fixation. One of the potential difficulties with absorbable implants is the possible toxicity of the polymeric degradation products especially if they accumulate and become concentrated. Accordingly, material evaluation must involve dose-response toxicity data as well as mechanical properties and degradation rates. In this study the toxicity and rates of degradation for six polymers were determined, along with the toxicity of their degradation product components. The polymers studied were poly(glycolic acid) (PGA), two samples of poly(L-lactic acid) (PLA) having different molecular weights, poly(ortho ester) (POE), poly(epsilon-caprolactone) (PCL), and poly(hydroxy butyrate valerate) (5% valerate) (PHBV). Polymeric specimens were incubated at 37 degrees C in 0.05 M Tris buffer (pH 7.4 at 37 degrees C) and sterile deionized water. The solutions were not changed during the incubation intervals, providing a worst-case model of the effects of accumulation of degradation products. The pH and acute toxicity of the incubation solutions and the mass loss and logarithmic viscosity number of the polymer samples were measured at 10 days, 4, 8, 12, and 16 weeks. Toxicity was measured using a bioluminescent bacteria, acute toxicity assay system. The acute toxicity of pure PGA, PLA, POE, and PCL degradation product components was also determined. Degradation products for PHBV were not tested. PGA incubation solutions were toxic at 10 days and at all following intervals. The lower molecular weight PLA incubation solutions were not toxic in buffer but were toxic by 4 weeks in water.(ABSTRACT TRUNCATED AT 250 WORDS)

Self‐hardening calcium phosphate composite scaffold for bone tissue engineering

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Bioresorbable polymers: heading for a new generation of spinal cages

“…In general, PLA (and related polymers like PGA) have demonstrated good biocompatibility and absence of significant toxicity, although some reduction in cell proliferation has been reported on PLA in vitro [106,107]. Also, it has been reported that PLA produces toxic solutions in vitro, probably as a result of the acidic degradation products [94].…”

“…Hollowel [46] reported that the endplate did not increase the resistance significantly when tested in compression until failure; Closkey [24] agreed but showed that a minimum contact area was needed to avoid subsidence. However, Steffen [94] and Polikeit [87,91] found that placement of cages in the central area of the vertebral body, whether the endplate has been removed or not, could cause early failure. More recently Lowe et al [70] showed that the central region of the endplate provided the least resistance.…”

Recent advances in materials for extended-release antibiotic delivery system

“…Nevertheless, the most frequently investigated biodegradable materials such as poly(lactic acid) or poly(glycolic acid) produce acidic degradation products that may accumulate and become concentrated, leading to toxicity. 26 A biocompatibility polymer poly(trimethylene carbonate) (PTMC) with no influence on the pH was explored. The surface erosion of PTMC occurred only in the presence of lipase and thus provided constant release of the antibiotics.…”