Background: Electronic cigarettes (e-cigarettes), the smokeless alternative to conventional tobacco cigarettes, have become increasingly popular. E-cigarettes vaporise e-liquid, a solution of highly concentrated nicotine, propylene glycol (PG) and vegetable glycerine (VG). With the popularity of e-cigarettes, e-liquid refills have become easily accessible and several cases of intoxication due to the ingestion of e-liquid have been reported. We provide an overview of these cases, their pathophysiology and patients' characteristics. Methods: We carried out a retrospective evaluation of the scientific literature reporting on cases of liquid nicotine intoxication, using the following inclusion criteria: (1) the article is or contains a case report, (2) describes an intoxication with e-liquid, (3) the substance contains nicotine, and (4) intake is oral, intravenous or subcutaneous. Results: We found 26 case reports describing a total of 31 patients who suffered from e-liquid intoxication. All intoxications up to the age of six were reported as unintentional, whereas nearly all cases from ages 13 to 53 were due to suicide attempts. The three most prevalent symptoms of e-liquid intoxication were tachycardia, altered mental status and vomiting. Eleven cases resulted in the death of the patient. In the survivors, the highest plasma concentration of nicotine was 800 mg L À1 , while the lowest concentration in the non-survivors was 1600 mg L À1 . Conclusions: There is a mismatch between the generally accepted lethal oral nicotine dose of 60 mg, resulting in approximately 180 mg L À1 plasma concentration, and the 4.4-to 8.9-fold higher lethal plasma concentrations we found in cases of e-liquid intoxication. In these severe intoxications, plasma cotinine concentration does not act as a more reliable indicator of nicotine intoxication than nicotine itself. The ages of the patients display a bimodal distribution. In patients above the age of 10, intoxication results mainly from suicide attempts rather than accidental ingestion. The role of PG and VG in e-liquid intoxications is remarkably unclear. However, the similarity across nicotine and PG toxicity symptoms leads us to believe a cumulative effect cannot be excluded. ARTICLE HISTORY

Background Recreational use of nitrous oxide (N 2 O) is associated with many side effects, of which neurological complications are most common. Nitrous oxide abuse is also associated with psychiatric symptoms, but these have received less attention so far. Vitamin B12 deficiency may play a role in the development of these psychiatric symptoms. Aims To explore the relationship among the occurrence of recreational nitrous oxide-induced psychiatric symptoms, accompanying neurological symptoms, vitamin B12 status and choice of treatment. Methods A retrospective search for case reports was conducted across multiple databases (Pubmed, Embase, Web of Science, PsycINFO and CINAHL). Keywords included variants of "nitrous oxide", "case report" and "abuse". No restrictions to language or publication date were applied. Results The search retrieved 372 articles. A total of 25 case reports were included, representing 31 patients with psychiatric complications following nitrous oxide abuse. The most often reported symptoms were: hallucinations (n ¼ 16), delusions (n ¼ 11), and paranoia (n ¼ 11). When neurological symptoms were present, patients were treated more frequently with vitamin B12 supplementation. Conclusions This review highlights the need to recognize that psychiatric symptoms may appear in association with nitrous oxide use. Approximately half of the cases that presented with nitrous oxideinduced psychiatric complaints did not show neurological symptoms, and their vitamin B12 concentration was often within the hospital's reference range. Psychiatrists and emergency physicians should be aware of isolated psychiatric symptoms caused by recreational nitrous oxide abuse. We suggest asking all patients with new psychiatric symptoms about nitrous oxide use and protocolizing the management of nitrous oxide-induced psychiatric symptoms.

4386 Introduction: A neutralization of anticoagulant activity occurs when heparin binds to a variety of positively charged substances such as protamine and platelet factor 4 (PF4). PMX60056 (PolyMedix, Radnor, PA) is a novel compound that is being developed as a heparin antagonist. Since heparin-PF4 complexes are antigenic, with antibodies against this complex activating platelets to trigger thrombin generation, thrombus formation and associated morbidities, it is of interest to determine whether heparin:PMX60056 complexes affect platelet function. This study compares the effect of PMX60056 and protamine, alone and complexed to heparin, on platelet function as assessed by platelet aggregometry. Materials and Method: Whole blood, collected from 10 healthy individuals, was anticoagulated with 3.2% sodium citrate and centrifuged to make platelet rich plasma (PRP). PRP was supplemented with 10 μ g/ml heparin (~1.5 IU/ml), 10 μ g/ml heparin antagonist (protamine or PMX 60056) or a complex of 10 μ g/ml heparin and 10 μ g/ml heparin antagonist. Platelet aggregation was stimulated by the addition of ADP (5 or 10 μ M final concentration) or serum from a patient with heparin-induced thrombocytopenia. Result: ADP-induced platelet aggregation was not affected by the addition of heparin, protamine, PMX 60056, or complexes of heparin with heparin antagonist. In the HIT system, heparin + HIT serum led to a significant increase in platelet aggregation vs. saline (46.7 ± 3.2 % vs. 8.2 ± 2.9%). HIT serum + heparin antagonist did not induce platelet aggregation (PMX60056: 10.2 ± 4.4%; protamine: 11.6 ± 3.5%). The aggregation responses to HIT serum + heparin (46.7 ± 3.2%), HIT serum + heparin:PMX60056 (43.6 ± 5.8%) and HIT serum + heparin:protamine (47.8 ± 3.8%) were not significantly different. Conclusion: When mixed at equigravimetric amounts, protamine and PMX60056 do not prevent formation of immune complexes consisting of HIT antibody and heparin which lead to platelet activation. Previous data from human trials has suggested that smaller amounts of PMX60056 (less than equigravimetric) may effectively neutralize heparin. Thus, it is speculated that smaller heparin:PMX60056 complexes may induce less antibody formation than larger heparin:protamine complexes. Validation of this hypothesis in animal models or clinical studies is warranted. Disclosures: McAllister: PolyMedix, Inc.: Employment.

1172 Background: Low molecular weight heparins (LMWHs) are complex biologic drugs that exhibit heterogeneity in terms of saccharide chain length and in the composition (sulfate, acetyl), content, and location of functional groups. Such heterogeneity impacts the biologic activity of LMWHs as there is a certain threshold chain length required for thrombin inhibitory activity and a particular sequence is required for interaction with antithrombin. In July 2010 the US Food and Drug Administration published requirements necessary to demonstrate the ‘sameness’ of generic LMWHs with the originator LMWH. We undertook this study to compare the primary anticoagulant effect of thrombosis prevention and the primary adverse effect of bleeding of two FDA approved generic enoxaparins. Methods: Four batches of commercially available Sandoz US generic enoxaparin (Princeton, NJ) and two batches of Watson US generic enoxaparin (Parsippany, NJ) were compared. All products were obtained from hospital pharmacies as pre-filled syringes containing 40 mg of the drugs. The molecular weight profile of each batch was determined by HPLC in relation to well-defined heparin fractions and by utilizing the US Pharmacopeia method. In vitro activity was determined by supplementing each LMWH batch to normal human plasma over a range of concentrations (0–10 mg/ml) and analyzing these samples using aPTT, anti-FXa and anti-FIIa assays. Hemorrhagic activity was measured using a rat tail transection model five minutes after administration of a 2 mg/kg intravenous dose (n=8 rats/batch). Upon completion of the bleeding model, antithrombotic activity was assessed using a jugular vein clamping model (∼90 minutes post-dosing). Blood samples collected from treated rats were used to estimate circulating blood levels of LMWH using anti-FXa and anti-FIIa assays. Results: The two groups of generic enoxaparins exhibited a similar molecular weight profile with mean molecular weights of 4,270 ± 20 Da for the Sandoz products and 4,420 ± 80 Da for the Watson products. In vitro activities were similar between batches of the same product, but the individual products differed considerably (p=0.01). In the aPTT and anti-FIIa assays, the Watson LMWH produced significantly more activity than the Sandoz LMWH at concentrations ≥5 μg/ml. At 5 μg/ml, a clotting time of 74.0 ± 16.6 sec was observed with Watson batches compared to clotting times ranging from 52.9 to 54.9 sec for Sandoz LMWHs. While a similar pattern was observed with the anti-FXa assay, the differences between products were not statistically significant. In the bleeding model, all LMWHs prolonged the bleeding time compared to vehicle control. One batch of the Watson LMWH, however, produced a significantly longer bleeding time compared to all other samples tested (33.8 ± 5.1 min vs. a range of 11.9 ± 2.4 to 18.3 ± 4.3 minutes for the other samples; p=0.003). The same batch produced significantly more antithrombotic activity (6.3 ± 0.7 clampings) compared to the other samples (range of 4.0 ± 0.6 to 4.6 ± 0.5 clampings; p<0.001). One batch of Sandoz LMWH produced a significantly smaller prolongation of bleeding time compared to other samples. Circulating drug levels determined by anti-FXa and anti-FIIa activities were comparable in all treatment groups but did not appear to correlate with hemorrhagic or antithrombotic activities. Conclusion: The expectation was that all batches of all generic enoxaparins would produce the same in vitro, in vivo, and ex vivo outcomes. The findings of this study suggest that incorporation of traditional animal models in the development of generic enoxaparins may be of value as multiple biological effects of LMWHs, not fully addressed with the anti-FXa and anti-FIIa activities, contribute to the overall antithrombotic activity of these LMWHs. This study demonstrates that all generic enoxaparins available today may not necessarily be the same. These findings underscore the importance of in vivo studies in animal models to demonstrate the bioequivalence of the generic products. Disclosures: Jeske: Sanofi-Aventis, Paris, France: Research Funding. Walenga:Sanofi-Aventis, Paris, France: Research Funding. Escalante:Sanofi-Aventis, Paris, France: Research Funding. Hoppensteadt:Sanofi-Aventis, Paris, France: Research Funding. Cunanan:Sanofi-Aventis, Paris, France: Research Funding. Kahn:Sanofi-Aventis, Paris, France: Research Funding. Paulus:Sanofi-Aventis, Paris, France: Research Funding. Fareed:Sanofi-Aventis, Paris, France: Research Funding. Bakhos:Sanofi-Aventis, Paris, France: Research Funding.