Platelet collagen receptor Glycoprotein VI-dimer recognizes fibrinogen and fibrin through their D-domains, contributing to platelet adhesion and activation during thrombus formation

Essentials Glycoprotein VI (GPVI) binds collagen, starting thrombogenesis, and fibrin, stabilizing thrombi. GPVI-dimers, not monomers, recognize immobilized fibrinogen and fibrin through their D-domains. Collagen, D-fragment and D-dimer may share a common or proximate binding site(s) on GPVI-dimer. GPVI-dimer-fibrin interaction supports spreading, activation and adhesion involving αIIbβ3.

SUMMARY

Background Platelet collagen receptor Glycoprotein VI (GPVI) binds collagen, initiating thrombogenesis, and stabilizes thrombi by binding fibrin. Objectives To determine if GPVI-dimer, GPVI-monomer, or both bind to fibrinogen substrates, and which region common to these substrates contains the interaction site. Methods Recombinant GPVI monomeric extracellular domain (GPVIex ) or dimeric Fc-fusion protein (GPVI-Fc2 ) binding to immobilized fibrinogen derivatives was measured by ELISA, including competition assays involving collagenous substrates and fibrinogen derivatives. Flow adhesion was performed with normal or Glanzmann thrombasthenic (GT) platelets over immobilized fibrinogen, with or without anti-GPVI-dimer or anti-αIIbβ3. Results Under static conditions, GPVIex did not bind to any fibrinogen substrate. GPVI-Fc2 exhibited specific, saturable binding to both D-fragment and D-dimer, which was inhibited by mFab-F (anti-GPVI-dimer), but showed low binding to fibrinogen and fibrin under our conditions. GPVI-Fc2 binding to D-fragment or D-dimer was abrogated by collagen type III, Horm collagen or CRP-XL (crosslinked collagen-related peptide), suggesting proximity between the D-domain and collagen binding sites on GPVI-dimer. Under low shear, adhesion of normal platelets to D-fragment, D-dimer, fibrinogen and fibrin was inhibited by mFab-F (inhibitor of GPVI-dimer) and abolished by Eptifibatide (inhibitor of αIIbβ3), suggesting that both receptors contribute to thrombus formation on these substrates, but αIIbβ3 makes a greater contribution. Notably, thrombasthenic platelets showed limited adhesion to fibrinogen substrates under flow, which was further reduced by mFab-F, supporting some independent GPVI-dimer involvement in this interaction. Conclusion Only dimeric GPVI interacts with fibrinogen D-domain, at a site proximate to its collagen binding site, to support platelet adhesion/activation/aggregate formation on immobilized fibrinogen and polymerized fibrin.

A Comparative, Double-blind, Randomised Trial of a New Second Generation LMWH (Bemiparin) and UFH in the Prevention of Post-operative Venous Thromboembolism

A randomised, prospective, double-blind trial was performed, to compare the safety and efficacy of a new low-molecular-weight heparin (LMWH) Bemiparin and standard unfractionated heparin (UFH), for the prophylaxis of postoperative venous thromboembolism. 300 patients scheduled to undergo elective hip arthroplasty were included. The principal outcome measures were the incidence of thromboembolic events and bleeding complications. 149 patients received 3,500 anti-Xa IU of bemiparin plus a placebo injection daily and 149 patients received 5,000 IU of UFH twice a day.

The two groups were similar with respect to factors likely to affect the risk of developing post-operative venous thromboembolism (VTE) and risk of bleeding events. During the post-operative period, 34 patients developed VTE complications; 9 (7.2%) in the bemiparin group and 25 (18.7%) in the UFH group. VTE in the two groups was statistically significant (OR of 2.96; 95% CI 1.32-6.62 and p = 0.01).

There were no significant differences in the frequency of bleeding complications: major bleeding requiring discontinuation of prophylaxis, (OR 1.21; 95% CI 0.36-4.05; p = 1.00), the measured median operative blood loss (p = 0.77) or the median postoperative drain loss (p = 0.97), and the number of patients who developed wound haematoma (OR 0.87; 95% CI 0.31-2.46; p = 1.00).

A comparison of coagulation parameters on the preoperative day with post-operative day 2 ± 1, day 6 ± 1 and day of discharge showed a significantly higher AT concentration, anti-factor Xa activity and TFPI levels in the bemiparin group when compared with UFH.

This study demonstrates that bemiparin, in a single daily subcutaneous dose of 3,500 anti-Xa IU in high risk patients undergoing hip arthroplasty is more effective than UFH administered twice daily at a dose of 5,000 IU in the prevention of postoperative VTE. Both agents are equally safe.

List of participants, their affiliations and current addresses are listed in the appendix on p. 528

Metallosis following implantation of magnetically controlled growing rods in the treatment of scoliosis: a case series

AIMS

We present a case series of five patients who had revision surgery following magnetic controlled growing rods (MGCR) for early onset scoliosis. Metallosis was found during revision in four out of five patients and we postulated a mechanism for rod failure based on retrieval analysis.

PATIENTS AND METHODS

Retrieval analysis was performed on the seven explanted rods. The mean duration of MCGR from implantation to revision was 35 months (17 to 46). The mean age at revision was 12 years (7 to 15; four boys, one girl).

RESULTS

A total of six out of seven rods had tissue metallosis and pseudo-capsule surrounding the actuator. A total of four out of seven rods were pistoning. There were two rods which were broken. All rods had abrasive circumferential markings. A significant amount of metal debris was found when the actuators were carefully cut open. Analytical electron microscopy demonstrated metal fragments of predominantly titanium with a mean particle size of 3.36 microns (1.31 to 6.61).

CONCLUSION

This study highlights concerns with tissue metallosis in MCGR. We recommend careful follow-up of patients who have received this implant. Cite this article: Bone Joint J 2016;98-B:1662-7.

Perception of Slope and Distance in Photographs and in the Real World

We report a series of experiments in which spatial judgments of the real world were compared with equivalent judgments of photographs of the real-world scenes. In experiment 1, subjects judged the angle from the horizontal of natural slopes. Judgments of slope correlated with true slope (r=0.88) but judgments were in general overestimates. Equivalent judgments of slope in photographs again correlated with true slope (r=0.91) but judgments tended to be overestimates for small angles (6°) and underestimates for larger angles (up to 25°). In experiment 2 slope judgments were made under laboratory conditions rather than in the natural world. The slopes, which were viewed monocularly, varied from 5° – 45°, and were either plain, or textured, or included perspective information (a rectangle drawn on the surface) or had both texture and perspective. Judgments were overestimates, but the correlation with true slope was high (r=0.97). Slopes with either texture or perspective were judged more accurately than plain slopes, but combining texture and perspective information conferred no further benefit. Judgment of the angle of the same slopes in photographs produced similar results, but the degree of overestimation (closer to the vertical) was greater than for the real slopes. In experiment 3, subjects either judged the distance of landmarks ranging from 200 m to 5000 m from the observation point, or judged distance to the landmarks in photographs. In both cases subjects' judgments were well described by a power function with exponents close to one. Although there are large individual differences, subjects' judgments of slope and distance are accurate to a scale factor, and photographs yield similar judgments to real scenes.

Early experience of MAGEC magnetic growing rods in the treatment of early onset scoliosis

PURPOSE

Magnetically controlled growing rod systems have been introduced over recent years as an alternative to traditional growing rods for management of early onset scoliosis. The purpose of this paper is to report our early experience of a magnetically controlled growing rod system (MAGEC, Ellipse).

METHODS

Review of pre-operative, postoperative and follow-up Cobb angles and spinal growth in case series of eight patients with a minimum 23 months' follow-up (23-36 months).

RESULTS

A total of six patients had dual rod constructs implanted and two patients received single-rod constructs. Four patients had MAGEC rods as a primary procedure. Four were revisions from other systems. Mean age at surgery in the primary group was 4.5 years (range 3.9-6.9). In patients who had MAGEC as a primary procedure, mean pre-operative Cobb angle was 74° (63-94), with postoperative Cobb angle of 42° (32-56) p ≤ 0.001 (43% correction). Mean Cobb angle at follow-up was 42° (35-50). Spinal growth rate was 6 mm/year. One sustained proximal screw pull out. A final patient sustained a rod fracture. Mean age at surgery in the revision group was 10.9 years (range 9-12.6). Mean pre-operative Cobb angle was 45° (34-69). Postoperative Cobb angle was 42° (33-63) (2% correction). Mean Cobb angle at follow-up was 44° (28-67). Mean spinal growth rate was 12 mm/year. Two patients developed loss of distraction.

CONCLUSION

MAGEC growing rod system effectively controls early onset scoliosis when used as either a primary or revision procedure. Although implant-related complications are not uncommon, the avoidance of multiple surgeries following implantation is beneficial compared with traditional growing rod systems.

The effects of delta1-cortienic acid on skin blanching, pharmacokinetics and stability of loteprednol etabonate

The effect of delta1-cortienic acid (delta1-CA) on human skin blanching activity of the soft corticosteroid, loteprednol etabonate (LE), has been studied. Ten volunteers had applied to their forearms a dose of LE ranging from 0.1 to 1 mM, or LE from 0.1 to 1 mM in combination with 2-times the concentration of delta1-CA (0.2 - 2mM). The results indicate that delta1-CA increased LE's effect on human vasoconstriction/skin blanching activity, both in the intensity and duration. This enhancing effect of delta1-CA was also observed in other blanching studies with other corticosteroids, such as hydrocortisone. The enhancement may occur through the displacement of LE bound to transcortin (also known as corticosteroid-binding globulin, or CBG) by delta1-CA as delta1-CA has a higher affinity for CBG than that for glucocorticoid receptor (GR), resulting in more free-LE to act on GR, and increased skin blanching. In rat studies, intravenous injection of delta1-CA (5-50 mg/kg) did not affect the pharmacokinetics of LE (5 mg/kg), indicating that delta1-CA is safe for combined use with LE. In stability studies, the presence of delta1-CA at the same concentrations as LE in aqueous suspension (0.1 and 0.2%) significantly increased the stability of LE. Thus, the combination of delta1-CA with LE serves an enhancing and stabilizing role while not impacting the pharmacokinetic properties of LE.

Is return to professional rugby union likely after anterior cervical spinal surgery?

We have examined the outcome in 19 professional rugby union players who underwent anterior cervical discectomy and fusion between 1998 and 2003. Through a retrospective review of the medical records and telephone interviews of all 19 players, we have attempted to determine the likelihood of improvement, return to professional sport and the long-term consequences. We have also attempted to relate the probability of symptoms in the neck and radicular pain in the arm to the position of play. Neck and radicular pain were improved in 17 patients, with 13 returning to rugby, the majority by six months after operation. Of these, 13 returned to their pre-operative standard of play, one to a lower level and five have not played rugby again. Two of those who returned to the game have subsequently suffered further symptoms in the neck, one of whom was obliged to retire. The majority of the players with problems in the neck were front row forwards.

A return to playing rugby union after surgery and fusion of the anterior cervical spine is both likely and safe and need not end a career in the game.

Cognitive effects of short-term use of raloxifene: a randomized clinical trial

Two questions regarding findings from the Women's Health Initiative are (1) What is the effect of various hormonal regimens including selective estrogen receptor modulators? and (2) Is the negative effect on cognitive functioning related to the older age (65+ years) of the women? This study addresses these two questions in a short-term randomized trial of the effects of raloxifene versus alendronate on cognition. The study found only one significant interaction where the raloxifene and alendronate group changed differently across the two testing occasions. Hence, raloxifene does not have any impact, positive or negative, on short-term cognitive functioning when compared to alendronate.

Influence of the N-acetylation polymorphism on the metabolism of talampanel: an investigation in fasted and fed subjects genotyped for NAT2 variants

Talampanel is a 2,3-benzodiazepine-type allosteric (noncompetitive) AMPA-antagonist currently being developed as an orally active, broad-spectrum anticonvulsant. Here, a detailed study of its N-acetylation in humans is presented using plasma concentration data of both TLP and its N-acetyl metabolite obtained from healthy volunteers (n = 28) genotyped for N-acetyltansferase NAT2 isozymes. Plasma samples were obtained for up to 48 h after a single oral dose of 75 mg TLP both in fasted and in fed subjects. A perfect correspondence could be established between the phenotype inferred before the study from genotyping and that determined after the study by using plasma metabolite-to-parent molar ratios confirming that this route of metabolism is indeed mediated by NAT2. Analysis of the data has been performed using both noncompartmental analysis and a custom-built, unified parent-metabolite PK model, which incorporates three different acetylation rates according to the genotype-based classification of each subject as slow, intermediate, or fast acetylator to simultaneously fit plasma levels for both TLP and its metabolite. This suggest that for TLP in humans, (i) N-acetylation represents only a relatively small fraction of its total elimination (about one-fourth in fast acetylators and much less in slow acetylators), (ii) acetylation is about eight-twelve times faster in fast and three-six times faster in intermediate acetylators than in slow acetylators, and (iii) the N-acetyl metabolite is eliminated faster than the parent TLP.

28-day oral toxicity study with soft corticosteroid BNP-166 in rats and dogs, followed by a 14-day recovery period

The aim of the present study was to evaluate the soft corticosteroid BNP-166 in rats and dogs treated orally with 0.2, 2.0, and 20.0 mg/kg for 28 days and the reversibility of any abnormalities during a 14-day post-dosing period. The test substance, BNP-166, was well tolerated during the 28-day treatment period. The observed changes were all characteristic for the pharmacological actions of a glucocorticoid. Treatment related changes occurred in the adrenals and thymus, and, to a lesser extent, in the lymph nodes, spleen and liver. There were no statistically significant reductions in the cortisol levels of all groups in the 0.2 and 2 mg/kg treatments. Significant reductions were observed in the high-dose group (20 mg/kg), but levels returned to normal by the end of the 14-day recovery period. Based on the results, the No Observable Adverse Effect Level (NOAEL) of BNP-166 soft corticosteroid in rat and dog after 28-day oral administration is 2 mg/kg. This value is approximately 40 times higher than that of budesonide. Pharmacodynamic and receptor binding studies have shown BNP-166 to have a similar potency to budesonide; therefore, BNP-166 can be considered safer when administered orally than other corticosteroids such as prednisolone or budesonide.

A comparative double-blind, randomised trial of a new second generation LMWH (bemiparin) and UFH in the prevention of post-operative venous thromboembolism. The Bemiparin Assessment group

A randomised, prospective, double-blind trial was performed, to compare the safety and efficacy of a new low-molecular-weight heparin (LMWH) Bemiparin and standard unfractionated heparin (UFH), for the prophylaxis of postoperative venous thromboembolism. 300 patients scheduled to undergo elective hip arthroplasty were included. The principal outcome measures were the incidence of thromboembolic events and bleeding complications. 149 patients received 3,500 anti-Xa IU of bemiparin plus a placebo injection daily and 149 patients received 5,000 IU of UFH twice a day. The two groups were similar with respect to factors likely to affect the risk of developing post-operative venous thromboembolism (VTE) and risk of bleeding events. During the post-operative period, 34 patients developed VTE complications; 9 (7.2%) in the bemiparin group and 25 (18.7%) in the UFH group. VTE in the two groups was statistically significant (OR of 2.96; 95% CI 1.32-6.62 and p = 0.01). There were no significant differences in the frequency of bleeding complications: major bleeding requiring discontinuation of prophylaxis, (OR 1.21; 95% CI 0.36-4.05; p = 1.00), the measured median operative blood loss (p = 0.77) or the median postoperative drain loss (p = 0.97), and the number of patients who developed wound haematoma (OR 0.87; 95% CI 0.31-2.46; p = 1.00). A comparison of coagulation parameters on the preoperative day with post-operative day 2 +/- 1, day 6 +/- 1 and day of discharge showed a significantly higher AT concentration, anti-factor Xa activity and TFPI levels in the bemiparin group when compared with UFH. This study demonstrates that bemiparin, in a single daily subcutaneous dose of 3,500 anti-Xa IU in high risk patients undergoing hip arthroplasty is more effective than UFH administered twice daily at a dose of 5,000 IU in the prevention of postoperative VTE. Both agents are equally safe.

A randomized, double-masked, placebo-controlled parallel study of loteprednol etabonate 0.2% in patients with seasonal allergic conjunctivitis

OBJECTIVE

To evaluate the effects of loteprednol etabonate (LE) 0.2% in reducing the signs and symptoms of seasonal allergic conjunctivitis.

DESIGN

Randomized, double-masked, placebo-controlled, parallel group multicenter study of 6 weeks duration.

PARTICIPANTS

A total of 135 patients with signs and symptoms of seasonal allergic conjunctivitis participated.

INTERVENTION

All patients received either LE 0.2% or placebo (vehicle) four times a day in both eyes for 42 days.

MAIN OUTCOME MEASURES

Bulbar conjunctival injection (primary sign) and itching (primary symptom) over the first 2 weeks of treatment was measured.

RESULTS

A reduction in severity was seen in both LE and placebo groups for bulbar conjunctival injection (1.5 vs. 1.0 units on a 0-3 scale) and itching (3.4 vs. 3.0 units on a 0-4 scale) over the first 2 weeks. The treatment effect by these measures was -0.5 and -0.4 units in favor of LE (P < or = 0.008). Resolution (i.e., the proportion of patients with signs or symptoms no longer present) at day 14 strongly favored LE-treated patients (36% and 15%; 58% and 38%, for injection and itching, respectively). Both treatments were well tolerated. One patient in each treatment group (1 of 67 and 1 of 68, respectively) had an elevation of intraocular pressure of 10 mmHg or greater during the 6 weeks of treatment.

CONCLUSIONS

Loteprednol etabonate 0.2% was more effective than placebo in the treatment of seasonal allergic conjunctivitis. Loteprednol etabonate 0.2% had a safety profile comparable to placebo.

The conjunctival provocation test model of ocular allergy: utility for assessment of an ocular corticosteroid, loteprednol etabonate

Two studies were conducted using the conjunctival provocation test (CPT) model of ocular allergy. The objective of the first study was to evaluate the sensitivity of the CPT model to a topical corticosteroid. Selected was loteprednol etabonate 0.5%, previously found effective in the treatment of ocular allergy and inflammation. The study was a randomized double-masked, placebo-controlled, paired-comparison of loteprednol etabonate 0.5% (LE), b.i.d. or q.i.d. Sixty subjects who had a minimum pre-determined allergic response received LE in one eye and placebo in the fellow eye for 28 days from Day 7 to Day 35. Antigen challenges were carried out on Days 0, 7 (baseline), 21 and 35. The primary endpoints were interocular differences in itching and mean redness (the average of ciliary, conjunctival and episcleral vessel beds). LE (either b.i.d. or q.i.d.) was significantly more effective than placebo for reducing mean redness and itching. No clinical or statistically significant changes in intraocular pressure were observed. Based upon the results of Study 1, we used the CPT model to aid in the selection of a concentration of loteprednol etabonate for subsequent studies in environmental seasonal allergic conjunctivitis. This was a randomized double-masked, placebo-controlled, paired-comparison of loteprednol etabonate 0.1%, 0.2% and 0.3%, q.i.d. in 88 subjects. The dosing and testing regimen was similar to the first portion of the study. Loteprednol etabonate, 0.1%, 0.2% and 0.3%, was numerically superior to the placebo in reducing mean redness and itching. At the 20-minute post allergen challenge, the 0.1% concentration was significantly superior (p < 0.05) to the placebo on Visit 4 (2 and 4 hour challenge) in reducing the mean redness; however, LE was only numerically superior in relieving itching. The 0.2% concentration was significantly superior (p < 0.05) to the placebo in the reduction of mean redness and itching on Visit 3 (Day 21) and in reduction of mean redness on Visit 4 (4 hour challenge). The 0.3% concentration was significantly superior (p < 0.05) to the placebo in the reduction of mean redness on all visits, and statistically significant in the reduction of itching on Visit 4 (4 hour challenge). While there were some elevations of IOP with LE 0.2%, they were not clinically significant. In conclusion, the CPT model of ocular allergy is useful in the evaluation of corticosteroids. Furthermore, based upon a dose-response study in this model, 0.2% loteprednol etabonate was selected for further evaluation in environmental seasonal allergic conjunctivitis studies.

Double-masked, placebo-controlled evaluation of loteprednol etabonate 0.5% for postoperative inflammation. Loteprednol Etabonate Post-operative Inflammation Study Group 1

PURPOSE

To compare the efficacy and safety of loteprednol etabonate 0.5% with those of a placebo (vehicle) in controlling anterior chamber cell and flare reaction in patients having cataract surgery with intraocular lens (IOL) implantation.

METHODS

This randomized, double-masked, placebo-controlled, parallel-group multicenter study comprised patients who exhibited a minimum anterior chamber inflammation (ACI) score (sum of cell and flare reaction) of 3 (0 to 9 scale) on the day after cataract removal with posterior chamber IOL implantation. All 227 patients received loteprednol etabonate 0.5% or the placebo 4 times a day in the operated eye for up to 14 days after surgery. Five patients without valid on-treatment follow-up visits were not evaluated for efficacy.

RESULTS

By the final visit, the ACI had resolved in 64% (70/109) of patients in the loteprednol etabonate group and 29% (33/113) of those in the placebo group (P < .001). The resolution rate and mean change from baseline of the individual components of ACI (cell and flare), as well as other signs and symptoms, was better in the loteprednol etabonate group. Both treatments were well tolerated. Among the 53 patients who did not complete the study, 34 (29%) were placebo patients discontinued for inadequate anti-inflammatory effect. The treatment failure rate and the time course of failures were lower in the loteprednol etabonate group; the differences were clinically meaningful and statistically significant (P < .001). Three patients in the loteprednol etabonate group had an intraocular pressure elevation of 10 mm Hg or more over the preoperative screening value.

CONCLUSION

Loteprednol etabonate 0.5% led to a clinically meaningful reduction in the signs and symptoms of postoperative ACI and had an acceptable safety profile when compared with a placebo.

A criterion-referenced measure of latex allergy knowledge

The exponential use of latex products has increased patients' and health care workers' sensitization to natural rubber latex. The purpose of this research study was to develop and test a set of items designed to measure professional nurses' knowledge about natural rubber latex reactions and interventions appropriate for latex precautions. The items were developed from research reports in the literature and changed to reflect the suggestions offered by experienced perioperative nurses (pilot = 8) and three nationally known experts in latex allergy responses. The revised form was mailed to the home or distributed at the workplace of perioperative nurses (n = 158). Criteria for item retention were < .90 difficulty index and clinical relevance. Certified nurses (i.e., CNORs) scored significantly higher than other nurses who took the test at the same time (t-test = 2.00, P = .05). A pretest and posttest evaluation of the revised 20 items was conducted before and after a latex allergy continuing education program during the spring of 1998. The current knowledge test (i.e., version 1.1) has reliability (alpha = .80); content validity (CVI = .92); and accumulated evidence of construct validity (preinstruction mean = 14.16, postinstruction mean = 17.15, t-paired = 10.54, df = 70, P = < .001). An empirically developed professional nurse latex allergy competency test suitable for clinical use was the outcome of this research study.

Change in intraocular pressure during long-term use of loteprednol etabonate

PURPOSE

Loteprednol etabonate is a novel site-active corticosteroid synthesized through structural modifications of prednisolone-related compounds so that it will undergo a predictable transformation to an inactive metabolite. In double-masked studies, loteprednol etabonate was effective in the treatment of giant papillary conjunctivitis, seasonal allergic conjunctivitis, postoperative inflammation, and uveitis. The objective of this analysis was to determine the incidence of clinically significant elevations in intraocular pressure (IOP) with long-term use of loteprednol etabonate.

PATIENTS AND METHODS

All subjects (healthy volunteers or patients with inflammation or allergy) in all sponsored loteprednol etabonate studies in the United States were evaluated. A clinically significant elevation in IOP was defined as > or = 10 mmHg at any visit, and long-term use was defined as > or = 28 days. Of the 2,210 subjects, 1,648 were treated for 28 days or longer with loteprednol etabonate (0.2% or 0.5%), prednisolone acetate 1%, or vehicle.

RESULTS

IOP elevation > or = 10 mmHg occurred in 1.7% (15/901) of patients taking long-term loteprednol etabonate, 0.5% (3/583) of those taking vehicle, and 6.7% (11/164) of those taking prednisolone acetate. Excluding patients who wore contact lenses, the incidence was 0.6% (4/624), 1.0% (3/304), and 6.7% (11/164) for loteprednol etabonate, vehicle, and prednisolone acetate, respectively. The incidence of IOP elevations with 0.2% loteprednol etabonate was 0.8% (1/133), similar to that for vehicle (0.7%, 1/135).

CONCLUSION

The results of this analysis in a large population of subjects undergoing long-term therapy and of a previously published controlled, double-masked study in corticosteroid responders suggest that loteprednol etabonate has less propensity to cause clinically significant elevations in IOP than prednisolone acetate.

A randomized, double-masked, placebo-controlled parallel study of 0.2% loteprednol etabonate in patients with seasonal allergic conjunctivitis

BACKGROUND

Loteprednol etabonate is a site-active corticosteroid with efficacy and safety in treating ocular inflammation at the 0.5% concentration. Evidence from dose-response studies suggested that the 0.2% concentration might be effective in treating ocular allergy.

OBJECTIVES

The objective of this study was to evaluate the effects of 0.2% loteprednol etabonate in reducing the signs and symptoms of seasonal allergic conjunctivitis.

METHODS

This was a randomized, double-masked, placebo-controlled, parallel-group multicenter study. Patients with signs and symptoms of environmental seasonal allergic conjunctivitis received either loteprednol etabonate or placebo bilaterally four times daily for 42 days.

RESULTS

Enrolled were 133 patients (66 receiving loteprednol etahonate; 67 receiving placebo). A reduction in severity was seen in both loteprednol etabonate and placebo groups for bulbar conjunctival injection (1.3 vs 0.9 units on a 0 to 3 scale) and itching (3.5 vs 3.1 units on a 0 to 4 scale) over the first 2 weeks. The treatment effect was -0.5 and -0.6 units in favor of loteprednol etabonate (P < .001). Resolution (the proportion of patients with the sign or symptom no longer present) at visit 4 (day 14) strongly favored loteprednol etabonate-treated patients over placebo-treated patients (31% and 9%, and 54% and 38%, for injection and itching, respectively). Both treatments were well tolerated. No patients in either treatment group (0 for loteprednol etabonate and 0 for vehicle) had an elevation of intraocular pressure of 10 mm Hg or greater during the 6 weeks of treatment.

CONCLUSIONS

Loteprenol etabonate (0.2%) was more effective than placebo in the treatment of seasonal allergic conjunctivitis. Loteprednol etabonate (0.2%) had a safety profile comparable to placebo during this 6-week trial.

Failure to detect systemic levels, and effects of loteprednol etabonate and its metabolite, PJ-91, following chronic ocular administration

The objective of this study was to determine the systemic exposure to loteprednol etabonate (LE) following its chronic, ocular instillation. This was a randomized, double-masked, placebo controlled, single center trial in 14 normal volunteers. Subjects were randomly assigned to receive either LE (n=10) or placebo (n=4) and instructed to instill one drop into each eye 8 times daily on Days 0 and 1 and four times daily on Days 2 through 42. Blood levels of loteprednol etabonate (LE) and its major metabolite PJ-91 (delta1 cortienic acid etabonate) in plasma, and circulating plasma cortisol levels were measured during the study. Plasma levels of LE or PJ-91 were below the level of quantitation (1 ng/mL) for all subjects in both treatment groups. Plasma cortisol levels were all within the normal range. Chronic exposure to LE at a concentration and frequency equal to or greater than the intended therapeutic dose does not result in detectable systemic levels or hypothalamic pituitary axis suppression.

A controlled evaluation of the efficacy and safety of loteprednol etabonate in the prophylactic treatment of seasonal allergic conjunctivitis. Loteprednol Allergic Conjunctivitis Study Group

PURPOSE

To evaluate the efficacy and safety of loteprednol etabonate 0.5% as prophylactic treatment for the ocular signs and symptoms of seasonal allergic conjunctivitis.

METHODS

In this randomized, double-masked, placebo-controlled, parallel study, 293 adults with history of seasonal allergic conjunctivitis were treated with either loteprednol etabonate or vehicle (placebo) four times daily, beginning before the onset of the allergy season and continuing for 6 weeks. The primary efficacy measure was a primary composite score (sum of itching and bulbar conjunctival injection scores). Supportive efficacy measures were the investigator global assessment and a secondary composite score (sum of tearing, erythema, chemosis, and discomfort scores), all calculated during the 21-day peak pollen season.

RESULTS

The proportion of patients who never developed moderate or severe signs and symptoms of allergy during the peak pollen season in the loteprednol etabonate treatment group was greater than that in the placebo group. For the primary composite score, this efficacy criterion was reached by 94% of patients (136/145) in the loteprednol etabonate group and 78% of patients (111/143) in the placebo group (P = .001). The magnitude of effect was similar for the investigator global assessment (86% [118/138] vs 64% [87/137]; P < .001) and, although not statistically significant, the secondary composite score (77% [112/145] vs 68% [97/143]; P = .092). None of the loteprednol etabonate-treated patients had an intraocular pressure increase of 10 mm Hg or more, whereas two placebo patients did.

CONCLUSIONS

Loteprednol etabonate is generally effective in prophylaxis of seasonal allergic conjunctivitis and has an acceptable safety profile.

A double-masked, placebo-controlled evaluation of the efficacy and safety of loteprednol etabonate in the treatment of giant papillary conjunctivitis. The Loteprednol Etabonate Giant Papillary Conjunctivitis Study Group I

PURPOSE

To evaluate the safety and effectiveness of loteprednol etabonate 0.5% ophthalmic suspension in reducing the ocular signs and symptoms accompanying contact lens-associated giant papillary conjunctivitis.

METHODS

In a randomized, double-masked, placebo-controlled, parallel-group study conducted at 14 academic or private practice clinics, 223 adults with contact lens-associated giant papillary conjunctivitis received either loteprednol or the loteprednol vehicle (placebo), one drop, four times daily for 6 weeks. Papillae, itching, contact lens intolerance, other signs and symptoms of giant papillary conjunctivitis (O-to-3 or O-to-4 grade scales), and intraocular pressure were measured.

RESULTS

The proportion of patients treated with loteprednol who at final visit demonstrated an improvement in papillae of at least one grade (78%, 85/109) was significantly greater than the proportion of those treated with placebo (51%, 56/110; P = .001). A treatment difference favoring loteprednol was seen with improvement in itching (95% vs 81%, 104/109 vs 89/110; P < .001) and lens intolerance (87% vs 77%, 95/109 vs 85/110; P = .053). Eight of 109 patients (7%, all taking loteprednol) had an intraocular pressure increase of 10 mm Hg or more on at least one visit during treatment. After discontinuation of loteprednol, intraocular pressure returned to normal levels. Both treatments were well tolerated, and no serious unexpected treatment-related medical events were reported.

CONCLUSIONS

The rapid therapeutic response combined with the low incidence and transient nature of any intraocular pressure increase suggests that loteprednol is an appropriate treatment for giant papillary conjunctivitis.

A double-masked, placebo-controlled evaluation of the efficacy and safety of loteprednol etabonate in the treatment of giant papillary conjunctivitis

PURPOSE

To evaluate the safety and effectiveness of loteprednol etabonate 0.5% ophthalmic suspension (LE) for reducing the ocular signs and symptoms accompanying contact lens associated giant papillary conjunctivitis (GPC). We conducted a randomized, double-masked, placebo-controlled, parallel study at 11 U.S. academic or private practice clinics.

METHODS

Two hundred and twenty adults with contact lens associated GPC were enrolled in this study. Patient were treated with either LE or the loteprednol etabonate vehicle (placebo), q.i.d. for 6 weeks. Papillae, itching, lens intolerance, as well as other signs and symptoms of GPC (0 to 3 or 0 to 4 point severity scales), and intraocular pressure were measured.

RESULTS

The proportion of patients treated with LE demonstrating an improvement in papillae of at least one grade (75%) was significantly greater than the proportion of those treated with placebo (50%, P < 0.001). A treatment difference favoring LE was also seen with improvement in itching (92% vs. 76%, P = 0.001) and lens intolerance (84% vs. 66%, P = 0.002). Three patients (all on LE) had an intraocular pressure (IOP) elevation of 10 mm Hg or higher from baseline on at least one on-treatment visit. Cessation of therapy was required in one of these patients.

CONCLUSIONS

Both treatments were well tolerated and no serious, unexpected, treatment-related medical events were reported. The rapid therapeutic response, combined with the low incidence, late development, and transient nature of any IOP elevation suggests that LE may be helpful in treating GPC.

Cerebrospinal fluid cutaneous fistula. An unusual complication of epidural anaesthesia

We describe two cases of cerebrospinal fluid-cutaneous fistula following epidural anaesthesia used for postoperative pain relief. In each case spinal headache occurred only after removal of the catheters and both patients were treated successfully with autologous blood patches.

Pharmacokinetic characterization and tissue distribution of the new glucocorticoid soft drug loteprednol etabonate in rats and dogs

Loteprednol etabonate, a new glucocorticoid soft drug with a characteristic chloromethyl ester function in the 17 beta-position, is currently in the early phases of clinical development. As the basis for human trials, this study describes a new reversed-phase high-performance liquid chromatographic method for the determination of levels of drug in plasma and urine samples and assesses the pharmacokinetic properties of loteprednol etabonate in dogs and rats. Intravenous administration of loteprednol etabonate (5 mg/kg) to dogs revealed a terminal half-life of 2.8 h, a volume of distribution of 3.7 L/kg, and a total body clearance of 0.9 L/h/kg. Intact loteprednol etabonate was not detectable in the urine. After oral administration of the drug (5 mg/kg) to dogs, only metabolites, but no intact drug, were found in the plasma, an indication for a high first-pass effect. A pronounced binding of the drug to plasma protein (> 90%) and a high erythrocyte-buffer partition coefficient of 7.8 were determined in vitro. Preliminary information about tissue distribution and possible metabolic pathways were obtained in rats after oral administration of a 14C-labeled loteprednol etabonate suspension (5 mg/kg). pH-selective extraction into ethyl acetate revealed three distinguishable fractions: (1) a neutral lipophilic fraction, presumably intact drug, (2) an acidic, lipophilic fraction, and (3) a hydrophilic nonextractable fraction. Levels of intact drug and metabolites were highest in liver and kidney, whereas significantly lower levels were found in other investigated organs (lung, brain, heart).(ABSTRACT TRUNCATED AT 250 WORDS)

Nalmefene: safety and kinetics after single and multiple oral doses of a new opioid antagonist

The aim of these two studies was to evaluate the safety and pharmacokinetics of oral nalmefene, a new orally effective opioid antagonist. In the first study, single ascending doses of 50, 100, 200, and 300 mg of nalmefene HCl were administered in double-blind fashion to four groups of healthy men. There were six subjects in each group; four received nalmefene and two received placebo. The drug was well tolerated at all dose levels with only mild and transient side effects, such as lightheadedness, at the higher doses. Model-independent pharmacokinetic analysis of the plasma concentration-time data showed that nalmefene was rapidly absorbed and had an elimination half-life that ranged from seven to 15 hours (mean, 10.7 hr). There was a good linear relationship (r = .97) between administered dose and total area under the curve at each dose level. Only about 4% of the dose was excreted in the urine as unchanged nalmefene, whereas up to 60% was excreted as a beta-glucuronidase/sulfatase hydrolysable conjugate(s) of nalmefene. In the second study, six healthy men were initially administered a single 50-mg dose of drug, and plasma samples were obtained at selected time intervals for 48 hours. A dosing schedule of 20 mg q12h was then started and continued for seven days. Plasma samples were collected immediately before each dose and at selected times for up to 48 hours after the last dose. The drug was well tolerated by all subjects, and no clinically significant adverse effects were observed during the seven-day administration period.(ABSTRACT TRUNCATED AT 250 WORDS)

Nalmefene: intravenous safety and kinetics of a new opioid antagonist

In a placebo-controlled, double-blind study we evaluated the safety and kinetics of a new narcotic antagonist, nalmefene, after 2, 6, 12, and 24 mg intravenous doses to healthy men. At each dose level four subjects received active drug and two received placebo. The drug was well tolerated at all dose levels with only mild and transient side effects, the most common of which was lightheadedness. The plasma concentration-time data were best fit with a triexponential equation, and the terminal elimination phase had a harmonic mean t1/2 of 8 to 9 hours. Only about 5% of the dose was excreted in the urine as intact nalmefene, with up to 60% excreted as nalmefene glucuronide. Although intersubject differences were noted, mean or dose-normalized mean kinetic parameters such as clearance, steady-state volume of distribution, terminal t1/2, and AUC showed no consistent trends related to increasing doses, indicating that nalmefene has linear pharmacokinetics.