Anaphylaxis from topical bovine thrombin (Thrombostat) during haemodialysis and evaluation of sensitization among a dialysis population

Hypersensitive Reactions During Hemodialysis Treatment: What Do We Need to Know?

Kidney replacement therapies (KRTs) including hemodialysis (HD) are one of the treatment options for most of the patients with end-stage kidney disease. Although HD is vital for these patients, it is not hundred percent physiological, and various adverse events including hypersensitivity reactions may occur. Fortunately, these reactions are rare in total and less when compared to previous decades, but it is still very important for at least two reasons: First, the number of patients receiving kidney replacement treatment is increasing globally; and the cumulative number of these reactions may be substantial. Second, although most of these reactions are mild, some of them may be very severe and even lead to mortality. Thus, it is very important to have basic knowledge and skills to diagnose and treat these reactions. Hypersensitivity reactions can occur at any component of dialysis machinery (access, extracorporeal circuit, medications, etc.). The most important preventive measure is to avoid the allergen. However, even with very specific test, sometimes the allergen cannot be found. In mild conditions, HD can be contained with non-specific treatment (topical creams, antihistaminics, corticosteroids). In more severe conditions, treatment must be stopped immediately, blood should not be returned to patient, drugs must be stopped, and rules of general emergency treatment must be followed.

Autologous fibrin glue versus sutures for conjunctival autograft in primary pterygium: a randomized clinical trial

PURPOSE

To describe and compare the autologous fibrin glue and traditional sutures for conjunctival graft attachment in patients undergoing primary pterygium excision surgery.

METHOD

A randomized clinical trial included patients who underwent pterygium surgery with conjunctival autologous graft (CAG). Using randomization, a single-trained surgeon performed graft fixation with autologous glue or sutures. The glue was prepared immediately before the surgery, using the patient's blood components. After centrifugation, the plasma was collected and enhanced with calcium gluconate. Postoperative assessments were performed on Days 1, 7, 21, 30 and 180. The study evaluated postoperative edema and pain and complications. The mean surgical time was compared. Recurrence of the pterygium was assessed 6 months postoperatively.

RESULTS

The study evaluated 61 eyes. Thirty-three eyes underwent pterygium surgery using the glue technique, and 28 underwent the traditional suture technique. Fifty-one patients (83.60%) had successful graft adhered to at the end of follow-up. Ten patients (10/33) lost their graft in the glue group, and only 69.70% maintained graft presence in the fourth week versus 100% of the patients in the suture group (p = 0.001). Pain scores were lower in the glue group, and clinical edema was significantly higher. There was no significant difference in graft retraction or the presence of granuloma, necrosis or postoperative infection.

CONCLUSION

Autologous fibrin glue is an affordable option for CAG fixation in particular contexts where commercial fibrin glue is unavailable, and it could offer advantages compared to sutures. A higher graft loss rate was observed and might be related to topical anesthesia, and improvements to the technique are needed.

CLINICALTRIALS

gov Identifier: NCT04151017. https://clinicaltrials.gov/ct2/show/NCT04151017?term=20170467&draw=1&rank=1 .

Advantages of Fibrin Polymerization Method without the Use of Exogenous Thrombin for Vascular Tissue Engineering Applications

Fibrin is widely used in vascular tissue engineering. Typically, fibrin polymerization is initiated by adding exogenous thrombin. In this study, we proposed a protocol for the preparation of completely autologous fibrin without the use of endogenous thrombin and compared the properties of the prepared fibrin matrix with that obtained by the traditional method. Fibrinogen was obtained by ethanol precipitation followed by fibrin polymerization by adding either exogenous thrombin and calcium chloride (ExThr), or only calcium chloride (EnThr). We examined the structure, mechanical properties, thrombogenicity, degradation rate and cytocompatibility of fibrin matrices. Factor XIII (FXIII) quantitative assay was performed by ELISA, and FXIII activity was assessed by SDS-PAGE detection of γ-γ cross-links. The results show that network structure of EnThr fibrin was characterized by thinner fibers. The EnThr fibrin matrices had higher strength, stiffness and resistance to proteolytic degradation compared to ExThr fibrin. EnThr fibrin matrices exhibited less thrombogenicity in vitro than ExThr, and retained high cytocompatibility. Thus, the proposed approach has several advantages over the traditional method, namely the fabrication of a completely autologous coating material that has better mechanical properties, higher resistance to proteolysis and lower thrombogenicity.

A randomized, controlled trial of Veriset™ hemostatic patch in halting cardiovascular bleeding

Background

Obtaining hemostasis during cardiovascular procedures can be a challenge, particularly around areas with a complex geometry or that are difficult to access. While several topical hemostats are currently on the market, most have caveats that limit their use in certain clinical scenarios such as pulsatile arterial bleeding. The aim of this study was to assess the effectiveness and safety of Veriset™ hemostatic patch in treating cardiovascular bleeding.

Methods

Patients (N=90) scheduled for cardiac or vascular surgery at 12 European institutions were randomized 1:1 to treatment with either Veriset™ hemostatic patch (investigational device) or TachoSil^® (control). After application of the hemostat, according to manufacturer instructions for use, time to hemostasis was monitored. Follow-up occurred up to 90 days post-surgery.

Results

Median time to hemostasis was 1.5 min with Veriset™ hemostatic patch, compared to 3.0 min with TachoSil^® (p<0.0001). Serious adverse events within 30 days post-surgery were experienced by 12/44 (27.3%) patients treated with Veriset™ hemostatic patch and 10/45 (22.2%) in the TachoSil^® group (p=0.6295). None of these adverse events were device-related, and no reoperations for bleeding were required within 5 days post-surgery in either treatment group.

Conclusion

This study reinforces the difference in minimum recommended application time between Veriset™ hemostatic patch and TachoSil^® (30 s versus 3 min respectively). When compared directly at 3 min, Veriset™ displayed no significant difference, showing similar hemostasis and safety profiles on the cardiovascular bleeding sites included in this study.

Comparison of autologous fibrin glue versus nylon sutures for securing conjunctival autografting in pterygium surgery

PURPOSE

To compare the safety, operating time, postoperative ocular signs, symptoms, overall patient satisfaction, complications rate and recurrence rate of autologous fibrin glue (AFG) and nylon suturing (NS) for attaching conjunctival autografts in pterygium surgery.

METHODS

A prospective, randomized, interventional study was performed among 120 patients (120 eyes) with primary pterygium. Superior conjunctival autograft was harvested and transferred on to bare sclera after pterygium excision. For attaching the autograft, AFG (n = 60 eyes) and NS (n = 60 eyes) were used. The patients were followed up for 12 months. The groups were compared for the safety, operative time, postoperative ocular signs, symptoms, overall patient satisfaction, recurrence and complications rate.

RESULTS

All conjunctival autografts in both groups were successfully attached. The average operating time for the AFG group was significantly shorter (P < 0.001). Postoperative symptoms were fewer for the AFG group than the suture group. After 12 months of follow-up, no recurrence was reported for the AFG group, but 8.3% of patients experienced recurrence in the NS group.

CONCLUSIONS

Our study demonstrated the superiority of AFG to NS in saving operating time and elimination of recurrence without any complications in pterygium surgery. AFG can obviate the need for suturing and increases the viability of tissue flaps. Additional studies are necessary to determine the long-term effects considering factors such as primary or recurrent status of pterygium, age and sex of patient, dose and duration of treatment for mitomycin C.

Hypersensitivity reactions in patients receiving hemodialysis

OBJECTIVE

To describe hypersensitivity reactions in patients receiving maintenance hemodialysis.

DATA SOURCES

PubMed search of articles published during the past 30 years with an emphasis on publications in the past decade.

STUDY SELECTIONS

Case reports and review articles describing hypersensitivity reactions in the context of hemodialysis.

RESULTS

Pharmacologic agents are the most common identifiable cause of hypersensitivity reactions in patients receiving hemodialysis. These include iron, erythropoietin, and heparin, which can cause anaphylactic or pseudoallergic reactions, and topical antibiotics and anesthetics, which lead to delayed-type hypersensitivity reactions. Many hypersensitivity reactions are triggered by complement activation and increased bradykinin resulting from contact system activation, especially in the context of angiotensin-converting enzyme inhibitor use. Several alternative pharmacologic preparations and dialyzer membranes are available, such that once an etiology for the reaction is established, recurrences can be prevented without affecting the quality of care provided to patients.

CONCLUSION

Although hypersensitivity reactions are uncommon in patients receiving hemodialysis, they can be life-threatening. Moreover, considering the large prevalence of the end-stage renal disease population, the implications of such reactions are enormous. Most reactions are pseudoallergic and not mediated by immunoglobulin E. The multiplicity of potential exposures and the complexity of the environment to which patients on dialysis are exposed make it challenging to identify the precise cause of these reactions. Great diligence is needed to investigate hypersensitivity reactions to avoid recurrence in this high-risk population.

A Novel Hemostatic Patch That Stops Bleeding in Cardiovascular and Peripheral Vascular Procedures

BACKGROUND

Achieving hemostasis during surgery is a common challenge across surgical specialties and procedures, including cardiovascular and peripheral vascular procedures. Although several hemostatic agents are available, they all become less effective as bleeding becomes more vigorous. Veriset™ hemostatic patch is a topical hemostatic agent that has been approved for use on solid organs and in soft tissue. The primary aim of these studies was to assess the safety of Veriset hemostatic patch during cardiovascular and peripheral vascular procedures.

METHODS

Adult domestic swine were given intraoperative anticoagulation and systemic antiplatelet therapy, and then underwent a variety of cardiovascular coronary artery bypass graft (CABG anastomosis and aortotomy closure) and peripheral vascular (carotid arteriotomy with patch angioplasty) procedures. Bleeding was identified or created from each anastomotic site and was brisk in many cases. Veriset hemostatic patch, Surgicel(®) Nu-Knit(®) absorbable hemostat, or standard of care treatment was applied topically to the site of bleeding, and time to hemostasis was monitored for each animal. Animals were assessed during and after the surgical procedure to determine the effects of treatment on vessel diameter, clinical laboratory parameters, and host tissue response and/or tissue integration.

RESULTS

Application of Veriset hemostatic patch had no effect on vessel diameter, similar to Surgicel Nu-Knit absorbable hemostat and standard of care treatment. Approximately 28 days after application, Veriset hemostatic patch and Surgicel Nu-Knit absorbable hemostat were completely absorbed, with no impact on serum chemistry profiles. Furthermore, Veriset hemostatic patch was as effective or more effective than Surgicel Nu-Knit absorbable hemostat when applied during carotid arteriotomy (30.0 ± 0.0 sec vs. 163.6 ± 86.9 sec, P < 0.001) and CABG anastomosis (91.9 ± 66.0 sec vs. 207.5 ± 159.2 sec, P = 0.053).

CONCLUSIONS

Veriset hemostatic patch exhibits similar safety as Surgicel Nu-Knit absorbable hemostat, with effectiveness against cardiovascular and peripheral vascular bleeding. If these preclinical results are confirmed in clinical trials, this highly effective patch with a topical application requiring less than 30 seconds is likely to prove useful in many clinical settings.

Safety and effectiveness of a synthetic hemostatic patch for intraoperative soft tissue bleeding

Background

Continuous bleeding after using conventional hemostatic methods involving energy, sutures, or clips, is a serious and costly surgical complication. Many topical agents have been developed to promote intraoperative hemostasis, but improvement is needed in both decreasing time to hemostasis and increasing ease of use. Veriset™ hemostatic patch is CE-marked for controlling bleeding on the liver and in soft tissue. In the current study, we aimed to gather further evidence for the safety and effectiveness of Veriset™ hemostatic patch in soft tissue bleeding during a variety of surgical procedures.

Methods

Thirty patients scheduled for nonemergency surgery, each with an intraoperative soft tissue bleeding site, were treated with Veriset™ hemostatic patch. Time to hemostasis was monitored, and adverse events were assessed during the 90 days after surgery.

Results

When Veriset™ hemostatic patch was used, hemostasis occurred within 5 minutes in 29/30 (96.7%) subjects and within 1 minute in 21/30 (70.0%) subjects. No device-related serious adverse events were recorded during the 30 days after surgery, and no reoperations for device-related bleeding complications were performed during the 5 days after surgery.

Conclusions

Veriset™ hemostatic patch is a safe and effective hemostat for controlling soft tissue bleeding during a variety of surgical procedures.

Perioperative anaphylaxis: diagnosis, evaluation, and management

Perioperative anaphylaxis can occur during or after surgery and can have life-threatening consequences. As anesthesia protocols become more complex and incorporate multiple agents to regulate physiologic processes intraoperatively, perioperative anaphylaxis is becoming increasingly recognized. The allergist should obtain detailed records from the anesthesiologist in order to perform appropriate testing to identify the likely causative agents. Testing should ideally be performed 4 to 6 weeks after the reaction to account for a refractory period after mast cell activation. This article includes 2 cases of perioperative anaphylaxis and reviews the historical elements that must be considered after a reaction has occurred.

Optimal treatment of anaphylaxis: antihistamines versus epinephrine

Anaphylaxis is a rapid, systemic, often unanticipated, and potentially life-threatening immune reaction occurring after exposure to certain foreign substances. The main immunologic triggers include food, insect venom, and medications. Multiple immunologic pathways underlie anaphylaxis, but most involve immune activation and release of immunomodulators. Anaphylaxis can be difficult to recognize clinically, making differential diagnosis key. The incidence of anaphylaxis has at least doubled during the past few decades, and in the United States alone, an estimated 1500 fatalities are attributed to anaphylaxis annually. The increasing incidence and potentially life-threatening nature of anaphylaxis coupled with diagnostic challenges make appropriate and timely treatment critical. Epinephrine is universally recommended as the first-line therapy for anaphylaxis, and early treatment is critical to prevent a potentially fatal outcome. Despite the evidence and guideline recommendations supporting its use for anaphylaxis, epinephrine remains underused. Data indicate that antihistamines are more commonly used to treat patients with anaphylaxis. Although histamine is involved in anaphylaxis, treatment with antihistamines does not relieve or prevent all of the pathophysiological symptoms of anaphylaxis, including the more serious complications such as airway obstruction, hypotension, and shock. Additionally, antihistamines do not act as rapidly as epinephrine; maximal plasma concentrations are reached between 1 and 3 hours for antihistamines compared with < 10 minutes for intramuscular epinephrine injection. This demonstrates the need for improved approaches to educate physicians and patients regarding the appropriate treatment of anaphylaxis.

Optimization of expression of untagged and histidine-tagged human recombinant thrombin precursors in Escherichia coli

The present study is focused on preparation of proper Escherichia coli expression system to ensure high yields of various modified precursors of human recombinant thrombin, a potential biopharmaceutical reagent. Two thrombin precursors, the smallest single-chain α-thrombin precursor prethrombin-2 and its shortened form prethrombin-2∆13, and their His-tagged forms were used. In order to determine the effect of the different lengths and amino acid compositions of affinity His-tag on the target protein expression level, a variety of the His-tag sequences were used. We found out that the protein expression efficiency was closely related to the codons used for encoding of amino acids of fusion histidine tag. Optimization of culture medium composition is another way to increase yield of the target protein. Suitable medium composition can ensure cell growth to high densities which is related to total yield of expressed protein. In this study, a new optimized complex medium for batch fermentation was developed. Addition of nutrients like a yeast extract and enzymatic casein hydrolysate to the defined medium components had a positive impact on protein expression, where relatively high expression level of the target protein from total amount of cellular proteins was achieved. Further, we have focused on trace element solution composition, and the optimized nickel and selenium concentrations were determined. Our results show that the composition of essential trace metal solution has a major impact not only on expression level, but it can also affect cell growth rate.

The long term immunological response of swine after two exposures to a salmon thrombin and fibrinogen hemostatic bandage

Experimental salmon thrombin/fibrinogen dressings have been shown to provide effective hemostasis in severe hemorrhage situations. The hypothesis for this study was that swine would still remain healthy without coagulopathy six months after exposure to salmon thrombin/fibrinogen dressings. Initial exposure was by insertion of the salmon dressing into the peritoneal cavity. Three months after the initial exposure, the same animals were subjected to two full thickness dermal wounds on the dorsal surface. One wound was bandaged with the salmon thrombin/fibrinogen bandage and the other wound was dressed with a standard bandage. The animals were monitored for an additional three months. Blood was drawn every 14 days over the six months for immunological and coagulation function analysis. All of the animals (8 pigs) remained healthy during the six month period and the dermal wounds healed without incidence. Lymph nodes and spleen showed signs of normal immune response and Western blots showed development of antibodies against salmon fibrinogen, but none of the animals made antibodies that recognized any species of thrombin. Coagulation parameters (fibrinogen concentration, thrombin time, PT and aPTT) and hematological parameters remained normal over the course of the study when compared to initial values of the subject swine.

Wound healing and the immune response in swine treated with a hemostatic bandage composed of salmon thrombin and fibrinogen

We investigated the inflammatory response in pigs exposed to salmon fibrinogen/thrombin dressings. Animals were exposed to the material in 3 ways: (a) thrombin and fibrinogen were injected intravenously, (b) dual full-thickness skin lesions were surgically created on the dorsal aspect of the swine and treated with the fibrinogen/thrombin bandage and a commercial bandage or (c) a fibrinogen/thrombin bandage was inserted through an abdominal incision into the peritoneal cavity. Blood was collected twice weekly and animals were sacrificed at 7, 10 or 28 days. Animals in the 28-day dermal lesion group were given an injection of salmon fibrinogen/thrombin at the 10 day point to simulate a second bandage application. The immune response manifested itself as induction of germinal centers in mesenteric lymph nodes and in the white pulp of the spleen. Examination of the histology of the skin and organs showed a cellular inflammatory response with granulation tissue and signs of edema that resolved by the 28-day stage. Antibodies reactive to salmon and human thrombin and fibrinogen were detected, but fibrinogen levels and coagulation processes were not affected. In conclusion, animals treated with salmon fibrinogen/thrombin bandages demonstrated a smooth recovery course in terms of both tissue healing and the immune response without adverse effects from the exposure to the fish proteins.

Topical thrombins: benefits and risks

Whether from surgical misadventure, inherent patient factors, or iatrogenic causes, postoperative bleeding can be a consequence of any surgical procedure. There are many methods and products available to assist in managing or preventing bleeding. For each method, there may be specific benefits and indications, but they may also carry some degree of risk. Topical thrombin is used extensively in many surgical specialties, especially in the cardiovascular and neurosurgical arenas where other hemostatic modalities may not be appropriate choices. As a class, topical thrombins are generally a safe and effective method for achieving intraoperative hemostasis; however, some members of the class carry associated risks with their use. For example, the United States Food and Drug Administration required the addition of a black-box warning to the prescribing information of bovine-derived thrombin, the oldest member of the class, due to concerns of immune-mediated coagulopathies developing after use. In addition, human thrombin derived from pooled plasma has its own, if theoretical, risk of transmitting infections due to viral or prion agents. We address the topical thrombin class and review each product in the context of the current literature.

The effect of thrombin activation of platelet-rich plasma on demineralized bone matrix osteoinductivity

BACKGROUND

Demineralized bone matrix is an osteoinductive and osteoconductive material that is often used in orthopaedic surgery to induce bone formation. Autologous platelet-rich plasma, which contains proliferative and chemoattractant growth factors, has been used as a demineralized bone matrix adjuvant with mixed results. One variable during clinical use appears to be whether the platelet-rich plasma is activated with thrombin or is implanted in a liquid form with intact platelets. The objective of the present study was to determine if platelet-rich plasma can increase the osteoinductivity of demineralized bone matrix when used without thrombin activation.

METHODS

The bioactivity of the demineralized bone matrix was evaluated in vitro by determining alkaline phosphatase production by C2C12 myoblast cells. The effect of thrombin activation on platelet-rich plasma was studied in vitro by evaluating osteosarcoma and bone marrow stromal cells for cell number and transforming growth factor-beta1 activation. Demineralized bone matrices supplemented with platelet-rich plasma, with or without thrombin activation, were implanted intramuscularly in athymic rats and were examined at fourteen, twenty-eight, and fifty-six days. Histological samples were analyzed for osteogenesis and chondrogenesis. Osteogenesis was further characterized on the basis of alkaline phosphatase activity.

RESULTS

In vitro, thrombin triggered an immediate release of growth factors from the platelet-rich plasma, and the platelet-rich plasma increased the number of both osteosarcoma and stromal cells in a dose-dependent manner. Thrombin activation of the platelet-rich plasma eliminated such stimulatory effects. In vivo, the platelet-rich plasma stimulated chondrogenesis on Day 14 and osteogenesis on Days 28 and 56, whereas thrombin-activated platelet-rich plasma acted as an inhibitor of such events. In addition, inflammatory cells were detected in demineralized bone matrix samples that were mixed with thrombin-activated platelet-rich plasma. These cells were not present in matrix mixed with platelet-rich plasma alone.

CONCLUSIONS

Platelet-rich plasma significantly increased in vivo demineralized bone matrix osteoinductivity only when used without thrombin activation.

Building an immune-mediated coagulopathy consensus: early recognition and evaluation to enhance post-surgical patient safety

Topical hemostats, fibrin sealants, and surgical adhesives are regularly used in a variety of surgical procedures involving multiple disciplines. Generally, these adjuncts to surgical hemostasis are valuable means for improving wound visualization, reducing blood loss or adding tissue adherence; however, some of these agents are responsible for under-recognized adverse reactions and outcomes. Bovine thrombin, for example, is a topical hemostat with a long history of clinical application that is widely used alone or in combination with other hemostatic agents. Hematologists and coagulation experts are aware that these agents can lead to development of an immune-mediated coagulopathy (IMC). A paucity of data on the incidence of IMC contributes to under-recognition and leaves many surgeons unaware that this clinical entity, originating from normal immune responses to foreign antigen exposure, requires enhanced post-operative vigilance and judicious clinical judgment to achieve best outcomes.

Postoperative bleeding may result from issues such as loosened ties or clips or the occurrence of a coagulopathy due to hemodilution, vitamin K deficiency, disseminated intravascular coagulation (DIC) or post-transfusion, post-shock coagulopathic states. Other causes, such as liver disease, may be ruled out by a careful patient history and common pre-operative liver function tests. Less common are coagulopathies secondary to pathologic immune responses. Such coagulopathies include those that may result from inherent patient problems such as patients with an immune dysfunction related to systemic lupus erythrematosus (SLE) or lymphoma that can invoke antibodies against native coagulation factors. Medical interventions may also provoke antibody formation in the form of self-directed anti-coagulation factor antibodies, that result in problematic bleeding; it is these iatrogenic post-operative coagulopathies, including those associated with bovine thrombin exposure and its clinical context, that this panel was convened to address.

The RETACC panel's goal was to attain a logical consensus by reviewing the scientific evidence surrounding IMC and to make recommendations for the clinical recognition, diagnosis and evaluation, and clinical management of these complications. In light of the under-recognition and under-reporting of IMC, and given the associated morbidity, utilization of health care resources, and potential economic impact to hospitals, the panel engaged in a detailed review of peer-reviewed reports of bovine thrombin associated IMC. From that clinical knowledge base, recommendations were developed to guide clinicians in the recognition, diagnosis, and management of this challenging condition.

Topical haemostatic agents

BACKGROUND

A variety of local haemostatic agents is now available to stop troublesome bleeding. These agents are indicated for use during surgical interventions where conventional methods of haemostasis are not applicable because of the site of surgery or the degree of bleeding.

METHOD

A literature search using the PubMed and ISI Web of Knowledge databases identified relevant studies on topical haemostatic agents. Manufacturers' recommendations were also sought through commercial websites.

RESULTS AND CONCLUSION

A significant body of evidence now exists to support the use of topical haemostatic agents in a wide variety of clinical situations. The advantages and disadvantages of many of these agents are highlighted.

Topical bovine thrombin and adverse events: a review of the literature

OBJECTIVE

To review published evidence suggesting a link between topical bovine thrombin (TBT) and important adverse events (AEs).

RESEARCH DESIGN AND METHODS

English language articles and abstracts were obtained from MEDLINE using combinations of text and MeSH terms for thrombin, bovine thrombin and their trade names. References from summary articles were also retrieved. Published case reports, review articles, and retrospective, prospective or observational studies involving either immunogenicity or AEs were selected for further assessment. Retrieved articles were evaluated separately as AE case reports, quantitative studies of antibodies, or quantitative studies of AEs.

MAIN OUTCOME MEASURES

Presence of case causal information, temporal pattern of case report publication, reproducibility of aggregate data findings, and study design features.

RESULTS

The major limitations of reviewed publications were insufficient information regarding TBT and other exposures, and designs in which linkage between laboratory immune phenomena and AEs could not be evaluated. While immunogenicity studies did support an increased risk for post-TBT antibodies, there was no consistent evidence that this led to an increased AE risk or severity. Common evidentiary deficiencies included case reports from high incidence environments, studies of combination or mixture products, biased study designs, lack of patient-level exposure data, inadequate control groups and insufficient sample sizes. The best designed study (a randomized, controlled comparison of TBT to a recombinant bovine product) documented post-TBT antibody production, but no important efficacy or AE differences. An examination of publication dates for case reports showed a peak between 1992 and 1994 followed by a substantial drop. Since 1997 the number of published AE case reports has continued to decline.

CONCLUSIONS

TBT increases the risk for antibody elevations in patients. A careful review of published evidence does not show that either TBT itself or any associated elevations in anti-bovine antibodies are risk factors for clinically important AEs.

Absorbable hemostatic agents

PURPOSE

The pharmacology, clinical efficacy, adverse effects and toxicities, drug interactions, dosage and administration, and safety issues related to the use of absorbable hemostatic agents are reviewed.

SUMMARY

Absorbable hemostatic agents exert their pharmacologic effects at various points within the coagulation cascade. These agents are indicated for use during surgical procedures as adjunctive therapy when bleeding is not controlled by conventional methods. Early clinical data on absorbable hemostatic agents revealed a beneficial effect with regard to controlling capillary bleeding, achieving hemostasis during vascular surgery, and controlling bleeding from fistula-puncture sites. Few randomized controlled clinical trials have directly compared available agents, but case reports describing the efficacy of absorbable hemostatic agents in specific situations, especially unlabeled uses of thrombin, abound. Existing trials have compared the efficacy of established agents with newer agents, including fibrin sealants, with varying results. A variety of rarely occurring adverse effects have been reported with the administration of absorbable hemostatic agents; some of these rare effects, such as paralysis, are quite severe. No standardized dosing regimens are available for these agents, although surgeons may have a preference for a particular regimen based on their own clinical experience. No drug interactions involving absorbable hemostatic agents have been published; however, the use of these agents with other medications that affect hemostasis may disrupt clot formation.

CONCLUSION

Absorbable hemostatic agents are useful as adjunctive therapy during surgical procedures when conventional methods do not control bleeding. Although rare adverse effects have occurred with these agents, their careful administration will prevent serious adverse outcomes.