Prevention of venous thromboembolic events in patients with lower leg immobilization after trauma: Systematic review and network meta-analysis with meta-epsidemiological approach.

BACKGROUND: Lower limb trauma requiring immobilization is a significant contributor to overall venous thromboembolism (VTE) burden. The clinical effectiveness of thromboprophylaxis for this indication and the optimal agent strategy are still a matter of debate. Our main objective was to assess the efficacy of pharmacological thromboprophylaxis to prevent VTE in patients with isolated temporary lower limb immobilization after trauma. We aimed to estimate and compare the clinical efficacy and the safety of the different thromboprophylactic treatments to determine the best strategy. METHODS AND FINDINGS: We conducted a systematic review and a Bayesian network meta-analysis (NMA) including all available randomized trials comparing a pharmacological thromboprophylactic treatment to placebo or to no treatment in patients with leg immobilization after trauma. We searched Medline, Embase, and Web of Science until July 2021. Only RCT or observational studies with analysis of confounding factors including adult patients requiring temporary immobilization for an isolated lower limb injury treated conservatively or surgically and assessing pharmacological thromboprophylactic agents or placebo or no treatment were eligible for inclusion. The primary endpoint was the incidence of major VTE (proximal deep vein thrombosis, symptomatic VTE, and pulmonary embolism-related death). We extracted data according to Preferred Reporting Items for Systematic Reviews and Meta-analyses for NMA and appraised selected trials with the Cochrane review handbook. Fourteen studies were included (8,198 patients). Compared to the control group, rivaroxaban, fondaparinux, and low molecular weight heparins were associated with a significant risk reduction of major VTE with an odds ratio of 0.02 (95% credible interval (CrI) 0.00 to 0.19), 0.22 (95% CrI 0.06 to 0.65), and 0.32 (95% CrI 0.15 to 0.56), respectively. No increase of the major bleeding risk was observed with either treatment. Rivaroxaban has the highest likelihood of being ranked top in terms of efficacy and net clinical benefit. The main limitation is that the network had as many indirect comparisons as direct comparisons. CONCLUSIONS: This NMA confirms the favorable benefit/risk ratio of thromboprophylaxis for patients with leg immobilization after trauma with the highest level of evidence for rivaroxaban. TRIAL REGISTRATION: PROSPERO CRD42021257669.

DLNO/DLCO ratio evolution under targeted therapy in patients with pulmonary hypertension.

The ratio of the diffusing capacity of the lung for carbon monoxide (DLCO) and for nitric oxide (DLNO) measured simultaneously is modified in patients with precapillary pulmonary hypertension (PH). The potential impact of targeted therapy on the DLCO/DLNO ratio is unknown. Simultaneous measurements of DLNO and DLCO were performed at baseline, 3-4 month follow-up (first evaluation) and 12-month follow-up (second evaluation) after initiation of targeted PH therapies in incident cases of precapillary PH. The main outcome was the change in DLNO/DLCO ratio under treatment between baseline and the first evaluation. Twenty-nine patients were included (mean age: 66.8 years, 62.1% female). No significant change in the DLNO/DLCO ratio was found between baseline and the first evaluation. Similarly, no significant differences were noted with regard to changes in Dm or Vc, the DLNO/DLCO ratio in different patient subgroups, or in the 20 patients evaluated at the second follow-up. Within the limitations of this study, the DLNO/DLCO ratio is not useful in monitoring the response to treatment in PH.

Statistical controversies in clinical research: limitations of open-label studies assessing antiangiogenic therapies with regard to evaluation of vascular adverse drug events-a meta-analysis.

Background: Previous meta-analyses have shown paradoxical increased risk of bleeding and thrombotic events in patients receiving antiangiogenics (AA) that may be simply explained by the studies design included. By a meta-epidemiological approach, we aim to investigate the impact of double-blind (DB) and open-label study designs on the risks of bleeding, venous thrombotic events (VTE) and arterial thrombotic events (ATE) in cancer patients treated with AA. Materials and methods: We searched Medline, Cochrane, ClinicalTrials.gov databases and proceedings of major oncology congresses for clinical trials published from January 2003 to January 2016. Randomized clinical trials that assigned patients with solid cancers to AA or control groups were eligible for inclusion. Combined odds ratios (ORs) for the risks of bleeding events, VTE and ATE were calculated for open and DB trials. Estimation bias of the treatment effect was determined by the ratio of OR, by dividing the OR values obtained in open-label trials by those obtained in DB trials. Results: The literature-based meta-analysis included 166 trials (72 024 patients). For bleeding events, comparison of AA versus control yielded an overall OR of 2.41 [95% confidence interval (95% CI) 2.12-2.73; P < 0.001], but this risk was overestimated by 1.68 (95% CI 1.33-2.13) in open-label studies. Concerning VTE, the OR was 1.19 (95% CI 1.04-1.35; P = 0.012) overall with AA, but this effect disappears when considering only DB trials (OR 0.99, 95% CI 0.83-1.17). The corresponding ratio of OR showed a significant overestimation of 1.53 (95% CI 1.19-1.96) in open-label trials. For ATE, an OR of 1.59 (95% CI 1.30-1.94; P < 0.001) was observed, associated with a significant overestimation of 1.65 (95% CI 1.13-2.43) in open-label trials. Conclusions: Open-label studies overestimated the risk of vascular adverse events with AA by at least 50%. Meta-analyses assessing adverse drug events should therefore be restricted to DB randomized trials.

Assessment of clinically relevant bleeding as a surrogate outcome for major bleeding: validation by meta-analysis of randomized controlled trials.

Essentials Surrogacy of clinically relevant bleeding (CRB) for major bleeding has never been validated. Our meta-analysis evaluated CRB surrogacy in trials of new versus traditional anticoagulants. Surrogacy was not validated in orthopedic surgery, venous thromboembolism or atrial fibrillation The difficulty in demonstrating the surrogacy may reflect a lack of homogeneity in its definition SUMMARY: Background Clinically relevant bleeding (CRB), comprising major bleeding and clinically relevant non-major bleeding, has been used as a surrogate for major bleeding in most anticoagulant trials. The validity of this surrogate to estimate trade-off between thrombotic and bleeding events in clinical trials was never assessed. Methods We systematically reviewed randomized phase III trials comparing new anticoagulants with the standard of care for venous thromboembolism prevention following major orthopedic surgery, venous thromboembolism (VTE) treatment, or stroke and systemic embolism prevention in atrial fibrillation (AF), and reporting both major bleeding and CRB rates. The validity of CRB as a surrogate for major bleeding was assessed according to the strength of the association between the relative risks of major bleeding and CRB, measured by the use of R2trial and its 95% confidence interval (CI). Results In the postoperative prophylactic setting (13 studies), major bleeding and CRB rates were 1.12% and 3.56%, respectively, and R2trial was 0.69 (95% CI 0.34-0.93). For acute VTE studies (n = 12), major bleeding and CRB rates were 1.87% and 9.07%; the corresponding R2trial values were 0.28 (95% CI 0.01-0.80) and 0.68 (95% CI 0.09-1.00) when only double-blind studies were considered (n = 7). For AF studies (n = 7; 22 strata), major bleeding and CRB rates were 4.82% and 15.3%, and R2trial was 0.59 (95% CI 0.15-0.82). Conclusion Despite an apparent correlation between CRB and major bleeding in major orthopedic surgery, AF, and double-blind acute VTE studies, the wide CIs suggest that CRB might not be an acceptable surrogate outcome in any of these settings.

Bleeding risk of terminally ill patients hospitalized in palliative care units: the RHESO study.

Essentials Bleeding incidence as hemorrhagic risk factors are unknown in palliative care inpatients. We conducted a multicenter observational study (22 Palliative Care Units, 1199 patients). At three months, the cumulative incidence of clinically relevant bleeding was 9.8%. Cancer, recent bleeding, thromboprophylaxis and antiplatelet therapy were independent risk factors. SUMMARY: Background The value of primary thromboprophylaxis in patients admitted to palliative care units is debatable. Moreover, the risk of bleeding in these patients is unknown. Objectives Our primary aim was to assess the bleeding risk of patients in a real-world practice setting of hospital palliative care. Our secondary aim was to determine the incidence of symptomatic deep vein thrombosis and to identify risk factors for bleeding. Patients/Methods In this prospective, observational study in 22 French palliative care units, 1199 patients (median age, 71 years; male, 45.5%), admitted for the first time to a palliative care unit for advanced cancer or pulmonary, cardiac or neurologic disease were included. The primary outcome was adjudicated clinically relevant bleeding (i.e. a composite of major and clinically relevant non-major bleeding) at 3 months. The secondary outcome was symptomatic deep vein thrombosis. Results The most common reason for palliative care was cancer (90.7%). By 3 months, 1087 patients (91.3%) had died and 116 patients had presented at least one episode of clinically relevant bleeding (fatal in 23 patients). Taking into account the competing risk of death, the cumulative incidence of clinically relevant bleeding was 9.8% (95% confidence interval [CI], 8.3-11.6). Deep vein thrombosis occurred in six patients (cumulative incidence, 0.5%; 95% CI, 0.2-1.1). Cancer, recent bleeding, antithrombotic prophylaxis and antiplatelet therapy were independently associated with clinically relevant bleeding at 3 months. Conclusions Decisions regarding the use of thromboprophylaxis in palliative care patients should take into account the high risk of bleeding in these patients.

[Influence of anticoagulant therapy during pregnancy on the peripartum and anesthesia delivery terms]. / Influence d'un traitement anticoagulant pendant la grossesse sur l'anesthésie per-partum et les modalités d'accouchement.

OBJECTIVES: The objective of the study was to evaluate the influence of anticoagulation on intrapartum anesthesia and delivery modalities. METHODS: This ancillary study is concerned with anticoagulated patients included in the study STRATHEGE, in the Saint-Etienne and Lyon University Hospital from 2007 to 2012, which are compared to a control population. The primary endpoint is to evaluate the type of anesthesia received by women in labor, according to the center at the time of delivery compared to no treatment. The secondary endpoints are comparing the input mode to work, mode of delivery, stop management arrangements of these treatments, the rate of thromboembolic and hemorrhagic complications. RESULTS: Two hundred and three cases were included and 812 controls, matched on age, body mass index and parity. 61.6% of the cases had an epidural during childbirth against 87% of controls (p<0.05), spinal rates (22.5% versus 1.85%) and general anesthesia (5.4% versus 0.7%) were higher in the case group. The delivery rate vaginally was 90% in controls, against 65% of cases. The postpartum hemorrhage rate was similar in both groups (p> 0.05). A relay of the low molecular weight heparin was performed in 63% of the cases in Lyon, but the types of anesthesia received according to the centers were similar. CONCLUSION: Anticoagulant therapy at the time of delivery, does not limit access to effective analgesia, but with an increased rate of spinal anesthesia and general anesthesia at the expense of epidural anesthesia. The management of a parturient anticoagulant is complex and still exists today, great care disparities in the various maternity hospitals.

Indirect comparison meta-analysis of two enoxaparin regimens in patients undergoing major orthopaedic surgery. Impact on the interpretation of thromboprophylactic effects of new anticoagulant drugs.

Two enoxaparin dosage regimens are used as comparators to evaluate new anticoagulants for thromboprophylaxis in patients undergoing major orthopaedic surgery, but so far no satisfactory direct comparison between them has been published. Our objective was to compare the efficacy and safety of enoxaparin 3,000 anti-Xa IU twice daily and enoxaparin 4,000 anti-Xa IU once daily in this clinical setting by indirect comparison meta-analysis, using Bucher's method. We selected randomised controlled trials comparing another anticoagulant, placebo (or no treatment) with either enoxaparin regimen for venous thromboembolism prophylaxis after hip or knee replacement or hip fracture surgery, provided that the second regimen was assessed elsewhere versus the same comparator. Two authors independently evaluated study eligibility, extracted the data, and assessed the risk of bias. The primary efficacy outcome was the incidence of venous thomboembolism. The main safety outcome was the incidence of major bleeding. Overall, 44 randomised comparisons in 56,423 patients were selected, 35 being double-blind (54,117 patients). Compared with enoxaparin 4,000 anti-Xa IU once daily, enoxaparin 3,000 anti-Xa IU twice daily was associated with a reduced risk of venous thromboembolism (relative risk [RR]: 0.53, 95% confidence interval [CI]: 0.40 to 0.69), but an increased risk of major bleeding (RR: 2.01, 95% CI: 1.23 to 3.29). In conclusion, when interpreting the benefit-risk ratio of new anticoagulant drugs versus enoxaparin for thromboprophylaxis after major orthopaedic surgery, the apparently greater efficacy but higher bleeding risk of the twice-daily 3,000 anti-Xa IU enoxaparin regimen compared to the once-daily 4,000 anti-Xa IU regimen should be taken into account.

Impact of double-blind vs. open study design on the observed treatment effects of new oral anticoagulants in atrial fibrillation: a meta-analysis.

BACKGROUND: The prospective, randomized, open, blinded endpoint evaluation (PROBE) design has been proposed as a valid alternative to the double-blind (DB) design for trials comparing new oral anticoagulants (NOAs) with INR-adjusted vitamin K antagonists in patients with non-valvular atrial fibrillation (NVAF). OBJECTIVES: To determine whether the observed treatment effects of NOAs in patients with NVAF differ between PROBE/open-label trials and DB trials. METHODS: All phase II or III trials were eligible. The main efficacy and safety outcomes were stroke/systemic embolism (SSE) and major bleeding, respectively. Other outcomes included ischemic SSE, hemorrhagic stroke, intracranial and extracranial bleeding, myocardial infarction, and all-cause and cardiovascular mortality. Interaction (Cochran's chi-squared test) between PROBE and DB designs was tested. RESULTS: Thirteen studies (61 620 patients) were included. For SSE, a greater treatment effect of NOAs vs. INR-adjusted warfarin was observed in PROBE trials (RR 0.76, CI 0.65-0.89) compared with DB trials (RR 0.88, CI 0.78-0.98), but the interaction test was non-significant (P = 0.16). A significant 67% enhancement of treatment effect was found with PROBE/open-label trials compared with DB trials (interaction test, P = 0.05) for hemorrhagic stroke. No other interaction was significant. A non-significant interaction (P = 0.07) between oral direct thrombin inhibitors (RR 0.33; 0.22-0.51) and factor Xa inhibitors (RR 0.54; 0.40-0.72) was seen. No heterogeneity was found for any outcome. CONCLUSIONS: Our meta-analysis showed no significant interaction of study design for the main efficacy and safety outcomes. However, the non-significantly exaggerated reduction in SSE suggests interdependence of treatment effect and PROBE design, especially for hemorrhagic stroke.

Antipsychotics: a real or confounding risk factor for venous thromboembolism?

In a meta-analysis of case-control studies, Zhang et al. (2011) found an increased risk of venous thromboembolic events (VTE) in patients exposed to antipsychotics (OR=2.39 [1.71-3.35]). Our updated meta-analysis including the 2 available cohort studies, recognized as a more relevant type of observational study, showed a weaker, but still strong association (OR=1.84 [1.39; 2.44]). In view of the lack of data on the confirmed risk factors for VTE in existing studies, prospective studies including adjustment for these risk factors are warranted to confirm this association and to assess the benefit/risk ratio of antipsychotics in high-risk patients.

[Single-dose intraincisional levobupivacaine infiltration in caesarean postoperative analgesia: a placebo-controlled double-blind randomized trial]. / Infiltration peropératoire de lévobupivacaïne après césariennes: étude randomisée en double insu contre placebo.

OBJECTIVES: The efficacy of single-dose intraincisional infiltration with levobupivacaine in postoperative analgesia and chronic pain after caesarean sections is unknown. STUDY: A placebo-controlled double-blind randomized trial. PATIENTS AND METHODS: After ethical approval, and written inform consent, 140 women scheduled for a caesarean section were randomly assigned and received 30mL of levobupivacaine 0.5% (L group) or saline (placebo-P group) into their wound. The primary endpoint was morphine consumption (using intravenous morphine patient-controlled analgesia) for the first 24h after surgery. At 1h to 48h, side effects, pain at rest and pain 2months later were recorded. RESULTS: All included patients had similar demographic and surgical characteristics. The morphine consumption was significantly lower in the L group at h6, h8 and h12 (considering both total intake and each request). At h4, the mean total morphine consumption was 25 (12) mg in the L group versus 31 (14) mg in the P group (P=0.05). Time until discharge and side effects including nausea-vomiting (14 vs 20%), wound scar complications (6 vs 8%) and chronic pain after 2months (25% in both groups complained of small pain, and 75% no pain) were similar between the two groups (P>0.05). CONCLUSION: Single-dose local infiltration of levobupivacaine 0.5% reduced opioid requirement at 12h, with no difference after 24h. www.clinicaltrials.com, number: NCT00621907.

Systematic review of trocar-site hernia.

BACKGROUND: Broad implementation of laparoscopic surgery has made trocar-related complications clinically important. Trocar-site hernia (TSH) is an uncommon, but potentially serious, complication that occasionally requires emergency surgery. This systematic review was conducted to establish the prevalence and risk factors for TSH. METHODS: The review was conducted according to the PRISMA guidelines. MEDLINE, Embase, Web of Science and the Cochrane Library were searched to 7 June 2010 for studies on TSH. RESULTS: Twenty-two articles were included. One study was a randomized clinical trial, five were prospective cohort studies and 16 were retrospective cohort studies. The prevalence of TSH is low, with a median pooled estimate of 0·5 (range 0-5·2) per cent. No meta-analysis on risk factors could be performed. Pyramidal trocars, 12-mm trocars and a long duration of surgery were identified as the most important technical risk factors for TSH. Older age and a higher body mass index were observed to be patient-related risk factors. CONCLUSION: TSH is an uncommon complication of laparoscopic surgery. The most important technical risk factors are the design and size of the trocars. The scientific evidence for recommendations to avoid TSH is sparse.

Maternal mortality attributable to vascular dissection and rupture in the Netherlands: a nationwide confidential enquiry.

OBJECTIVE: To determine the incidence of maternal deaths attributable to vascular dissection and rupture in the Netherlands, and to assess clinical features, risk factors and the frequency of substandard care in the cases identified. DESIGN: Confidential enquiry into the causes of maternal deaths. SETTING: Nationwide in the Netherlands. POPULATION: A total of 3,108,235 live births. METHODS: Data analysis of all cases of maternal death from vascular dissection and rupture in the period 1993-2008. A literature review was also performed. MAIN OUTCOME MEASURES: Incidence, clinical features, risk factors and frequency of substandard care. RESULTS: A total of 23 maternal deaths attributable to vascular dissection and rupture were reported. In most cases the location was aortic (n=13), followed by coronary (n=4) and splenic (n=3) arteries. Clinical features were various, but most women presented with sudden unexplainable pain. Risk factors were present in 14 cases (61%), with hypertension being most frequently reported in ten cases (43%). Substandard care was determined to have been received in 13 cases (56%), inadequate assessment of complaints and a delay in diagnosis being the most frequent problems identified. CONCLUSIONS: Vascular dissection and rupture in pregnancy, although rare, carry a high risk of maternal and fetal morbidity and mortality. Because of the rarity of this condition and its variety in presentation, diagnosis is easily missed. A high index of suspicion when a woman presents with suggestive complaints, leading to an early diagnosis, may improve the prognosis for the woman and her child.

Individual patient data meta-analysis of enoxaparin vs. unfractionated heparin for venous thromboembolism prevention in medical patients.

BACKGROUND: Unfractionated heparin (UFH) and low-molecular-weight heparin (LMWH) are both recommended for venous thromboembolism (VTE) prophylaxis in hospitalized medical patients. OBJECTIVE: To perform an individual patient data meta-analysis to evaluate the relative efficacy and safety of the LMWH enoxaparin and UFH in preventing VTE in hospitalized medical patients. METHODS: Randomized clinical trials comparing subcutaneous enoxaparin (4000 IU once-daily) and UFH (5000 IU subcutaneous two- or three-times daily) for VTE prevention were identified by a systematic search. Individual patient data were obtained from each eligible trial. RESULTS: Overall, four trials were eligible, including 3600 patients randomized to receive enoxaparin (n = 1799) or UFH (n = 1801). Median patient age was 71 years, and 49.3% were female. Compared with UFH, enoxaparin was associated with risk reductions of 37% for total VTE [relative risk (RR) 0.63, 95% confidence interval (CI) 0.51-0.77] and 62% for symptomatic VTE (RR 0.38, 95% CI 0.17-0.85) at day 15. RR for total VTE in stroke and non-stroke patients was 0.59 (95% CI 0.47-0.74) and 0.87 (95% CI 0.51-1.50), respectively. Major bleeding rates were consistently low and similar between treatment groups at day 15 (RR 1.13, 95% CI 0.53-2.44). There was a trend towards reduced risk for mortality in patients receiving enoxaparin (RR 0.83, 95% CI 0.64-1.08), compared with UFH. CONCLUSIONS: Enoxaparin significantly reduces VTE in hospitalized medical patients, compared with UFH, without increasing the risk for major bleeding, and was associated with a trend towards reduced all-cause mortality.

Thrombin generation and heparin-induced thrombocytopenia.

BACKGROUND: Heparin-induced thrombocytopenia (HIT) is a severe complication of heparin therapy. IgG antibodies targeting the platelet factor 4-heparin complex activate platelets and generate microparticles with procoagulant activity. OBJECTIVES: To determine whether the thrombin generation assay is capable of detecting procoagulant activity induced by patient platelet-poor plasma (PPP) in donor platelet-rich plasma (PRP). PATIENTS AND METHODS: We explored two groups of patients; group 1 (n = 23): patients with a positive clinical and biological diagnosis of HIT; group 2 (n = 25): patients with a negative clinical and biological diagnosis of HIT. Mixtures of donor PRP and patient PPP (1:1) were incubated either with unfractionated heparin 0.2 U mL(-1) or with physiological saline. Thrombin generation was assessed by calibrated thrombinography. The effect of heparin on the mixtures was evaluated according to the ratio of the values with and without heparin (wH/woH) of the five thrombogram parameters. RESULTS: With low heparin concentrations, plasma of group 1 activates donor platelets and generates procoagulant activity. A set of three ratios outside the cut-off values corresponds to the 'HIT thrombogram profile', characterized by a highly specific aspect of the thrombogram wH in relation to the thrombogram woH. None of the group 2 patients presented a HIT thrombogram profile. The results of thrombinography correlate well with the results of the platelet aggregation test. CONCLUSION: Our studies illustrate the central paradox of HIT, namely enhancement of thrombin generation in the presence of heparin. The HIT thrombogram profile as it is defined in this study can detect the procoagulant activity of HIT IgG antibodies.

[Stress and seborrheic dermatitis]. / Stress et dermatite séborrhéique.

BACKGROUND: It is widely accepted that episodes of seborrheic dermatitis are frequently induced by stress, as stated in all general reviews of the subject. However, there have been no studies to confirm this view. PATIENTS AND METHODS: This prospective study was performed in two phases. An initial questionnaire collected information on patients' identity, somatic and psychiatric history and seborrheic dermatitis characteristics. Information on triggering episodes was sought by means of an open question and patients were then asked if they had experienced stress during the week or month prior to the active episode. A second questionnaire containing the same questions (except for history) was completed four months later. The two questionnaires contained psychopathological evaluation scales designed to detect symptoms of anxiety and depression among patients (HAD: Hospital Anxiety and Depression scale; Beck; STAI: State-Trait Anxiety Inventory) and determine their perceived stress (PSS: Perceived Stress Scale by Cohen and Williamson). RESULTS: Eighty-two patients (36 women and 46 men) were included in the study. 82% of patients presented involvement of scalp, 33% of the face, 19% of the chest and 13% of other sites (ears, skinfolds). Patients themselves identified stress as the main triggering factor, whether for episodes in general, for the first episode or for the current episode. A stressful event was in fact found in the majority of cases. The fact that stress was recognised as a triggering factor for episodes was not associated with a higher depression score (HAD or Beck) but was associated with a higher anxiety score (STAI). The psychological effects of the disease were pronounced in 11% of patients, moderate in 20%, mild in 35%, and nil in 25%, with 9% of patients stating no opinion. Patients with facial involvement were more depressed in terms of Beck Depression Index score. Two characteristics noted at inclusion were predictive for the onset of at least one further episode or persistence of an ongoing episode four months later: patients' designation of stress as the cause of the previous episode, and STAI score. DISCUSSION: This study confirms that seborrheic dermatitis is often preceded by a stressful event and that stress tends to suggest a poor prognosis. This is the first study to show a possible link between stressful life events and episodes of seborrheic dermatitis. It suggests the need to confirm these results through a study comparing patients with seborrheic dermatitis and subjects without the disease. It also shows that depression is more common among patients with facial involvement and that anxiety is an aggravating factor.

Introduction of a nitroxide group on position 2 of 9-phenoxyacridine: easy access to spin labelled DNA-binding conjugates.

In the search for spin labelled intercalators of general use to construct DNA-binding conjugates, 6-chloro-2-[(1-oxyl-2,2,5,5-tetramethyl- pyrrolin-3-yl)methyloxy]-9-phenoxy-acridine 5, has been prepared. This key-intermediate reacts with amines to give the corresponding labelled 9-amino substituted acridines. Comparative EPR and fluorescence measurements show that the label causes only little modification of the binding properties of acridine.