Saturday, December 16, 2006

Pipeline: Adhesion Barriers

A modern biomaterial for adhesion prevention.
Dizerega GS, Cortese S, Rodgers KE, Block KM, Falcone SJ, Juarez TG, Berg R.
Department of Obstetrics and Gynecology, Livingston Reproductive Biology Laboratories, Keck-USC School of Medicine, Los Angeles, California. A biomaterial composed of carboxymethylcellulose, poly(ethylene oxide), and calcium can be prepared in a variety of ways to reduce fibrin deposition and adhesion formation. This biomaterial platform can be formulated into a flowable gel with tissue adherence appropriate for use in minimally invasive surgery. The device remains at the site of placement even in gravitationally dependent areas. A peridural formulation was shown in preclinical studies to be safe and effective in reducing adhesions to dura following spinal surgery. A peritoneal formulation used on pelvic organs following peritoneal cavity surgery was also shown to be safe and effective. A clinical feasibility study showed that patients with severe back pain and lower extremity weakness treated with the peridural formulation, applied over their nerve roots following laminectomy or laminotomy, experienced significantly reduced symptoms when compared with surgery-only controls. The peritoneal formulation was shown in two multicenter feasibility studies of women undergoing pelvic surgery to significantly reduce adhesion formation when compared with surgery-only controls. Confirmation of the feasibility studies awaits results from pivotal clinical trials. These formulations were safe, effective, and easy to use. This biomaterial provided a benefit to patients undergoing surgery where postsurgical adhesion formation is a concern. (c) 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006. PMID: 16969823 [PubMed - as supplied by publisher]

A-part gel-An efficient adhesion prevention barrier.
Weis C, Odermatt EK. B. Braun Aesculap AG & Co. KG, R&D Closure Technologies, Postfach 40, 78501 Tuttlingen, Germany. Two different poly(vinyl alcohol)-based gels (A-Part Gel) were compared and evaluated as possible adhesion prophylaxis gels. The gels were implanted to act as a physical barrier-and thus to prevent adhesions-in a rabbit sidewall model. The absorption time of any adhesion barrier is a critical parameter, since the wounded tissue needs to be covered during the healing process. Crosslinking by freeze-thawing helped to prolong the absorption time of the gels. To better understand the in vivo absorption, the gels were investigated in various physical in vitro methods such as decay measurements and experiments performed in a Soxhlet extraction thimble. The in vivo applicability of the gels by surgeons was judged in squeezing force measurements. The ability to cover the wounded area securely was measured with simple spreading experiments. Both gels could be squeezed out of the syringes easily and showed a homogenous spreading behavior. Comparing the two gels, the results of the in vitro absorption experiments were contradictive. Further, in vivo tests with correlations to the proposed in vitro measurements will reveal the correct interpretation. Nevertheless, the results in a pilot rabbit sidewall model were excellent for both A-Part gels, but only one gel was chosen for extended studies, showing only 20% adhesions when compared with the control group showing 100% strong adhesion formations. These data will be evaluated in other studies, and the use of an A-Part PVA-CMC gel for adhesion prevention has to be supported in clinical studies. (c) 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006. PMID: 17106894 [PubMed - as supplied by publisher] J Biomed Mater Res B Appl Biomater.

Innovative barriers for peritoneal adhesion prevention: liquid or solid? A rat uterine horn model.
Wallwiener M, Brucker S, Hierlemann H, Brochhausen C, Solomayer E, Wallwiener C. Department of Obstetrics and Gynaecology, University of Tuebingen, Tuebingen, Germany. OBJECTIVE: To compare the effects of solid barriers (PDLA membrane and foil, Interceed), innovative barrier solutions (Adept and Hyalobarrier Gel, phospholipid emulsion), and Ringer's lactate solution in preventing postsurgical peritoneal adhesions in the rat. DESIGN: Prospective, randomized experimental study. SETTING: Rat model in an academic research environment. ANIMAL(S): Female, nonpregnant Wistar rats. INTERVENTION(S): Standardized surgical injuries were applied to the parietal and visceral peritoneum and the uterine horns. The barrier agents were applied and the wound was closed. A second-look laparoscopy was performed 31 days after surgery to assess adhesion formation. MAIN OUTCOME MEASURE(S): Severity and extent of adhesion formation assessed using a multidimensional adhesion scoring system. RESULT(S): Significantly fewer postsurgical adhesions were seen after treatment with Adept, Hyalobarrier Gel, Interceed, PDLA membrane, and phospholipid emulsion than after Ringer's lactate solution. Severe, clinically relevant adhesions were not observed after Hyalobarrier Gel and in only one animal after Adept. CONCLUSION(S): Both solid and liquid barriers can prevent adhesions. Hydroflotation formulas, such as Adept and Hyalobarrier Gel, avoid suture-induced adhesions, are easy to use, and their protective effects are evenly distributed. They are suitable for adhesion prevention after multifocal trauma in rats, and require further testing in the everyday clinical situation. PMID: 17008150 [PubMed - indexed for MEDLINE] Fertil Steril.

No comments: