Efficacy and safety of cinobufacini injection combined with vinorelbine and cisplatin regimen chemotherapy for stage III/IV non-small cell lung cancer: A protocol for systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: The main component of cinobufacini injection is dry toad skin, which is used as adjuvant therapy for stage III/IV non-small cell lung cancer patients in long-term combination with vinorelbine and cisplatin. However, the efficacy and safety of this combination therapy remain unclear. METHODS: A systematic review and meta-analysis will be conducted following the preferred reported items for systematic review and meta-analysis guidelines. Two independent reviewers (LRL and ZLN) will carry out a comprehensive search of the PubMed, Web of Science, Cochrane Library, EMBASE, the Chinese Science and Technology Periodical Database, China National Knowledge Infrastructure, Wanfang Databases, China Biology Medicine. The last search date will be July 30, 2020. Reference list of all selected articles will independently screened to identify additional studies left out in the initial search. The Cochrane Risk of Bias Tool will be used to evaluate the risk of bias of the randomized controlled trials. Outcome index: The main efficacy indicators were based on the objective efficacy evaluation criteria of the World Health Organization antineoplastic drugs or the objective efficacy evaluation criteria of solid tumors established by RECIST. Secondary criteria Karnofsky performance scale (KPS) score, pain efficacy criteria, side effects of chemotherapy such as myelosuppression and gastrointestinal symptoms. Assessment of risk of bias and data synthesis will be conducted using Review Manager V5.3 software. RESULTS: This study will systematically evaluate the efficacy and safety of cinobufacini combined with vinorelbine and cisplatin in the treatment of stage III/IV non-small cell lung cancer. The results of this systematic review will be published in peer-reviewed scientific journals. ETHICS: The ethical approval is not required since systematic review is based on published studies. INPLASY REGISTRATION NUMBER: INPLASY202060091.

Cinobufotalin injection combined with chemotherapy for the treatment of advanced NSCLC in China: A PRISMA-compliant meta-analysis of 29 randomized controlled trials.

BACKGROUND AND OBJECTIVE: Cinobufotalin injection (CFI), a kind of Chinese medicine, has been considered as a promising complementary therapy option for advanced non-small cell lung cancer (NSCLC), but their efficacy and safety remain controversial. This study aimed to systematically evaluate the efficacy and safety of CFI and chemotherapy-combined therapy for advanced NSCLC. METHODS: Clinical trials were searched from Web of Science, Cochrane Library, PubMed, Embase, China National Knowledge Infrastructure (CNKI), Chinese Biological Medicine Database (CBM), Chinese Medical Citation Index (CMCI), Wanfang database and Chinese Scientific Journal Database (VIP). Main measurements, including therapeutic efficacy, quality of life (QoL) and adverse events, were extracted from the retrieved publications and were systematically evaluated. RESULTS: The 29 trials including 2300 advanced NSCLC patients were involved in this study. Compared with chemotherapy alone, its combination with CFI significantly prolonged the patients' 1-, 2- and 3-year overall survival rate (OS) (1-year OS, OR = 1.94, 95% CI = 1.42-2.65, P < .0001; 2-year OS, OR = 2.31, 95% CI = 1.55-3.45, P < .0001; 3-year OS, OR = 4.69, 95% CI = 1.78-12.39, P = .002) and improved patients' overall response (ORR, OR = 1.84, CI = 1.54-2.18, P < .00001), disease control rate (DCR, OR = 2.09, 95% CI = 1.68-2.60, P < .00001) and QoL (quality of life improved rate, QIR, OR = 2.64, 95% CI = 1.98-3.52, P < .00001; karnofsky performance score, KPS, OR = 10.97, 95% CI = 5.48-16.47, P < .0001). Most adverse events caused by chemotherapy were obviously alleviated (P < .05) when CFI was also applied to patients. CONCLUSION: The combination of CFI and chemotherapy is safe, and is more effective in treating NSCLC than chemotherapy alone. Therefore, CFI mediated therapy could be recommended as an adjuvant treatment method for NSCLC.

Platelet-membrane-biomimetic nanoparticles for targeted antitumor drug delivery.

BACKGROUND: Nanoscale drug-delivery systems (DDSs) have great promise in tumor diagnosis and treatment. Platelet membrane (PLTM) biomimetic DDSs are expected to enhance retention in vivo and escape uptake by macrophages, as well as minimizing immunogenicity, attributing to the CD47 protein in PLTM sends "don't eat me" signals to macrophages. In addition, P-selectin is overexpressed on the PLTM, which would allow a PLTM-biomimetic DDS to specifically bind to the CD44 receptors upregulated on the surface of cancer cells. RESULTS: In this study, porous nanoparticles loaded with the anti-cancer drug bufalin (Bu) were prepared from a chitosan oligosaccharide (CS)-poly(lactic-co-glycolic acid) (PLGA) copolymer. These were subsequently coated with platelet membrane (PLTM) to form PLTM-CS-pPLGA/Bu NPs. The PLTM-CS-pPLGA/Bu NPs bear a particle size of ~ 192 nm, and present the same surface proteins as the PLTM. Confocal microscopy and flow cytometry results revealed a greater uptake of PLTM-CS-pPLGA/Bu NPs than uncoated CS-pPLGA/Bu NPs, as a result of the targeted binding of P-selectin on the surface of the PLTM to the CD44 receptors of H22 hepatoma cells. In vivo biodistribution studies in H22-tumor carrying mice revealed that the PLTM-CS-pPLGA NPs accumulated in the tumor, because of a combination of active targeting effect and the EPR effect. The PLTM-CS-pPLGA/Bu NPs led to more effective tumor growth inhibition over other bufalin formulations. CONCLUSIONS: Platelet membrane biomimetic nanoparticles played a promising targeted treatment of cancer with low side effect.

Clinical effect of intravenous infusion of zoledronic acid combined with oral medication of cinobufagin in the treatment of metastatic bone tumors.

Aim of the study was to observe and analyze the clinical effect of intravenous infusion of zoledronic acid combined with oral medication of cinobufagin in treating metastatic bone tumors. The 120 patients who have been treated in the hospital for metastatic bone tumor from June 2014 to June 2017 were selected as research objects. They were randomly divided into research group and control group, each containing 60. The research group was treated with intravenous infusion of zoledronic acid combined with oral medication of cinobufagin. In the control group, only zoledronic acid intravenous infusion was administered. The overall treatment effect of the two groups was observed. The pain of two groups was evaluated using numerical rating scale (NRS). The results showed that compared with the control group, the research group achieved better clinical effect and had a higher quality of life, and the intergroup difference was of statistical significance, P<0.05. There was no difference in rate of adverse reactions between the two groups, P>0.05, without statistical significance. The combined therapy of intravenous infusion of zoledronic acid and oral medication of cinobufagin can obtain better therapeutic effect in treating metastatic bone tumors.

Clinical study on thalidomide combined with cinobufagin to treat lung cancer cachexia.

OBJECTIVE: To discuss and assess the clinical value of treating lung cancer cachexia with thalidomide combined with cinobufagin.s. METHODS: A cohort of 54 patients, who were diagnosed with lung carcinoma, was randomly divided into two groups, a trial group and a control group, respectively. The trial group was given 150 mg/day thalidomide and 2700 mg/day cinobufagin; the control group only received 2,700 mg/day cinobufagin. The therapy lasted for 12 weeks, and the nutritional status, quality of life, survival, and side effects in patients in the two groups were recorded. RESULTS: The nutritional status, quality of life, and survival of patients with lung cancer cachexia in the trial group were significantly improved compared to the control group. The trial group received 150 mg thalidomide, which by contrast reduced the incidence of side effect and increased tolerance. CONCLUSION: Using thalidomide combined with cinobufagin to treat patients with lung cancer cachexia will significantly improve their nutritional status and quality of life. This therapy is better than that using cinobufagin alone and is well tolerated.

Bufalin, a bufanolide steroid from the parotoid glands of the Chinese toad, suppresses hERG K+ currents expressed in HEK293 cells.

In this study, we investigated the effect of bufalin on the human ether-à-go-go-related gene (hERG) K+ channels using the perforated patch recording technique. We measured a half-maximal inhibitory concentration (IC50 ) of 24.83 µM and maximal inhibitory effect of 39.45 ± 1.14% with bufalin. These findings suggest that bufalin is a potent hERG K+ channel blocker and may provide a new way for understanding Chan Su-induced arrhythmia.

TXNIP/TRX/NF-κB and MAPK/NF-κB pathways involved in the cardiotoxicity induced by Venenum Bufonis in rats.

Venenum Bufonis (VB) is a widely used traditional medicine with serious cardiotoxic effects. The inflammatory response has been studied to clarify the mechanism of the cardiotoxicity induced by VB for the first time. In the present study, Sprague Dawley (SD) rats, were administered VB (100, 200, and 400 mg/kg) intragastrically, experienced disturbed ECGs (lowered heart rate and elevated ST-segment), increased levels of serum indicators (creatine kinase (CK), creatine kinase isoenzyme-MB (CK-MB), alanine aminotransferase (ALT), aspartate aminotransferase (AST)) and serum interleukin (IL-6, IL-1ß, TNF-α) at 2 h, 4 h, 6 h, 8 h, 24 h, and 48 h, which reflected that an inflammatory response, together with cardiotoxicity, were involved in VB-treated rats. In addition, the elevated serum level of MDA and the down-regulated SOD, CAT, GSH, and GPx levels indicated the appearance of oxidative stress in the VB-treated group. Furthermore, based on the enhanced expression levels of TXNIP, p-NF-κBp65, p-IκBα, p-IKKα, p-IKKß, p-ERK, p-JNK, and p-P38 and the obvious myocardial degeneration, it is proposed that VB-induced cardiotoxicity may promote an inflammatory response through the TXNIP/TRX/NF-κB and MAPK/NF-κB pathways. The observed inflammatory mechanism induced by VB may provide a theoretical reference for the toxic effects and clinical application of VB.

Marinobufagenin-induced vascular fibrosis is a likely target for mineralocorticoid antagonists.

OBJECTIVE: Endogenous cardiotonic steroids, including marinobufagenin (MBG), stimulate vascular synthesis of collagen. Because mineralocorticoid antagonists competitively antagonize effect of cardiotonic steroids on the Na/K-ATPase, we hypothesized that spironolactone would reverse the profibrotic effects of MBG. METHODS: Experiment 1: Explants of thoracic aortae and aortic vascular smooth muscle cells from Wistar rats were cultured for 24 h in the presence of vehicle or MBG (100 nmol/l) with or without canrenone (10 µmol/l), an active metabolite of spironolactone. Experiment 2: In 16 patients (56 ±â€Š2 years) with resistant hypertension on a combined (lisinopril/amlodipine/hydrochlorothiazide) therapy, we determined arterial pressure, pulse wave velocity, plasma MBG, and erythrocyte Na/K-ATPase before and 6 months after addition of placebo (n = 8) or spironolactone (50 mg/day; n = 8) to the therapy. RESULTS: In rat aortic explants and in vascular smooth muscle cells, pretreatment with MBG resulted in a two-fold rise in collagen-1, and a marked reduction in the sensitivity of the aortic rings to the vasorelaxant effect of sodium nitroprusside following endothelin-1-induced constriction (EC50 = 480 ±â€Š67 vs. 23 ±â€Š3 nmol/l in vehicle-treated rings; P < 0.01). Canrenone blocked effects of MBG on collagen synthesis and restored sensitivity of vascular rings to sodium nitroprusside (EC50 = 17 ±â€Š1 nmol/l). Resistant hypertension patients exhibited elevated plasma MBG (0.42 ±â€Š0.07 vs. 0.24 ±â€Š0.03 nmol/l; P = 0.01) and reduced Na/K-ATPase activity (1.9 ±â€Š0.15 vs. 2.8 ±â€Š0.2 µmol Pi/ml per h, P < 0.01) vs. seven healthy individuals. Six-month administration of spironolactone, unlike placebo treatment, was associated with a decrease in pulse wave velocity and arterial pressure, and with restoration of Na/K-ATPase activity in the presence of unchanged MBG levels. CONCLUSION: MBG-induced vascular fibrosis is a likely target for spironolactone.

Characterization of phase I metabolism of resibufogenin and evaluation of the metabolic effects on its antitumor activity and toxicity.

Resibufogenin (RB), one of the major active compounds of the traditional Chinese medicine Chansu, has displayed great potential as a chemotherapeutic agent in oncology. However, it is a digoxin-like compound that also exhibits extremely cardiotoxic effects. The present study aimed to characterize the metabolic behaviors of RB in humans as well as to evaluate the metabolic effects on its bioactivity and toxicity. The phase I metabolic profile in human liver microsomes was characterized systemically, and the major metabolite was identified as marinobufagenin (5ß-hydroxylresibufogenin, 5-HRB) by liquid chromatography-mass spectrometry and nuclear magnetic imaging techniques. Both cytochrome P450 (P450) reaction phenotyping and inhibition assays using P450-selective chemical inhibitors demonstrated that CYP3A4 was mainly involved in RB 5ß-hydroxylation with much higher selectivity than CYP3A5. Kinetic characterization demonstrated that RB 5ß-hydroxylation in both human liver microsomes and human recombinant CYP3A4 obeyed biphasic kinetics and displayed similar apparent kinetic parameters. Furthermore, 5-HRB could significantly induce cell growth inhibition and apoptosis in A549 and H1299 by facilitating apoptosome assembly and caspase activation. Meanwhile, 5-HRB displayed very weak cytotoxicity of human embryonic lung fibroblasts, and in mice there was a greater tolerance to acute toxicity. In summary, CYP3A4 dominantly mediated 5ß-hydroxylation and was found to be a major metabolic pathway of RB in the human liver, whereas its major metabolite (5-HRB) displayed better druglikeness than its parent compound RB. Our findings lay a solid foundation for RB metabolism studies in humans and encourage further research on the bioactive metabolite of RB.

Reduction of Na/K-ATPase potentiates marinobufagenin-induced cardiac dysfunction and myocyte apoptosis.

Decreases in cardiac Na/K-ATPase have been documented in patients with heart failure. Reduction of Na/K-ATPase α1 also contributes to the deficiency in cardiac contractility in animal models. Our previous studies demonstrate that reduction of cellular Na/K-ATPase causes cell growth inhibition and cell death in renal proximal tubule cells. To test whether reduction of Na/K-ATPase in combination with increased cardiotonic steroids causes cardiac myocyte death and cardiac dysfunction, we examined heart function in Na/K-ATPase α1 heterozygote knock-out mice (α1(+/-)) in comparison to wild type (WT) littermates after infusion of marinobufagenin (MBG). Adult cardiac myocytes were also isolated from both WT and α1(+/-) mice for in vitro experiments. The results demonstrated that MBG infusion increased myocyte apoptosis and induced significant left ventricle dilation in α1(+/-) mice but not in their WT littermates. Mechanistically, it was found that in WT myocytes MBG activated the Src/Akt/mTOR signaling pathway, which further increased phosphorylation of ribosome S6 kinase (S6K) and BAD (Bcl-2-associated death promoter) and protected cells from apoptosis. In α1(+/-) myocytes, the basal level of phospho-BAD is higher compared with WT myocytes, but MBG failed to induce further activation of the mTOR pathway. Reduction of Na/K-ATPase also caused the activation of caspase 9 but not caspase 8 in these cells. Using cultures of neonatal cardiac myocytes, we demonstrated that inhibition of the mTOR pathway by rapamycin also enabled MBG to activate caspase 9 and induce myocyte apoptosis.

Marinobufagenin and cyclic strain may activate endothelial NADPH oxidase, contributing to the adverse impact of salty diets on vascular and cerebral health.

Limited but provocative ecologic epidemiology suggests that dietary salt may play a central role in the genesis of not only of stroke, but also dementia, including Alzheimer's disease. Impairment of nitric oxide bioactivity in the cerebral microvasculature is a likely mediator of this effect. Salted diets evoke increased adrenal secretion of the natriuretic steroid marinobufagenin (MBG), which promotes natriuresis via inhibition of renal tubular Na+/K+-ATPase; this effect is notably robust in salt-sensitive rodent strains in which other compensatory natriuretic mechanisms are subnormally efficient. MBG-mediated inhibition of sodium pumps in vascular smooth muscle likely plays a role in the hypertension induced by salty diets in these rodents. However, salt sensitivity in humans is associated with increased vascular mortality and ventricular hypertrophy independent of blood pressure; this suggests that MBG may be pathogenic via mechanisms unrelated to blood pressure control. Indeed, recent evidence indicates that MBG, via interaction with alpha1 isoforms of the sodium pump, can activate various intracellular signaling pathways at physiological concentrations too low to notably inhibit pump activity. An overview of current evidence suggests the hypothesis that MBG - as well as the cyclic strain induced by hypertension per se - may induce endothelial oxidative stress by activating NADPH oxidase. If so, this could rationalize the increase in vascular and systemic oxidative stress observed in salt-sensitive rodents fed salty diets, or in rodents infused with MBG; moreover, if this effect is a particularly prominent determinant of oxidative stress in cerebrovascular endothelium, it might help to explain the virtual absence of stroke and dementia in low-salt societies. As a corollary of this hypothesis, it can be predicted that spirulina-derived phycobilins, which appear to mimic the physiological role of bilirubin as an inhibitor of NAPDH oxidase complexes, may have potential for ameliorating the adverse health impacts of MBG and of salty diets. Potassium-rich diets are also likely to be protective in this regard, as they should suppress MBG production via their natriuretic impact, while their stimulatory effect on sodium pump activity may exert a hyperpolarizing effect on plasma membranes that suppresses NADPH oxidase activity.

[Clinical re-evaluation of effects of two different "cocktail therapy" to prevent from phlebitis induced by Chansu injection].

OBJECTIVE: To re-evaluate the effects of different "cocktail therapy" to prevent from phlebitis induced by Chansu injection. METHOD: Patients treated with Chansu injection were divided randomLy into 4 groups with 90 per group, control group, phentolaminum group, the magnesium sulfate group-phentolaminum group, and anisodamine-phentolaminum group. Patients in the control group only received the routine nursing treatment, and patients in the various experiment group received different interventions. The comparison was made in the morbidity and the starting time of occurrence of phlebitis, the severity of pain, duration of pain. RESULT: The morbidity of phlebitis was 8%, 8%, 6%, respectively. The starting time of phlebitis occurrence was (22 +/- 4), (27 +/- 5), (28 +/- 7) h, respectively. The NRS of pain was (4.75 +/- 1.51), (3.27 +/- 1.02), (2.71 +/- 1.63), respectively. The duration time of pain was (4.25 +/- 1.36), (2.51 +/- 1.05), (2.19 +/- 1.13) d respectively. In control group, the morbidity of phlebitis, the starting time of occurrence of phlebitis, the severity of pain, duration of pain was 30%, (16 +/- 4) h, (6.34 +/- 1.21), (5.47 +/- 1.07) d, respectively. As compared with the control group, a significance difference was found between every group in three test groups and control group respectively (P<0.05). CONCLUSION: The morbidity and the starting time of occurrence of phlebitis, the severity of pain, duration of pain was significantly reduced respectively by two different "cocktail therapy".

[Experimental study of suspicious sensitization component screening on Huachansu injection].

OBJECTIVE: To explore a new experimental method for screening of allergens in post-market traditional Chinese medicine injections by confirming allergens in Huachansu injection. METHOD: First of all, the serum of patients allergic to Huachansu injection were collected, at the same time, the dubious allergen was conjugated to bovine serum albumin (BSA) by EDC coupling procedure to form complete antigen (BNP-BSA), which makes it possible to reproduce the allergic reaction of Huachansu injection in vitro. The histamine liberation ratio, the level of TNF-alpha and Histamine released from RBL-2H3 mast cell were detected; the above data were compared with those obtained in vivo. RESULT: The difference of the histamine liberation ratio, the levels of TNF-alpha and histamine of the resibufogenin-BSA group, group of patients allergic to Huachansu injection were not significant compared with those of normal control group. However, there were significant difference in those data among the cinobufagin-BSA group, the blank control and normal control group (P<0.05). CONCLUSION: The allergen in the serum collected from patients allergic to Huachansu injection is resibufogenin.

[Clinical re-evaluation of effects of different treatments to prevent from phlebitis induced by Chansu injection].

OBJECTIVE: To re-evaluate the effects of different treatments to prevent from phlebitis induced by Chansu injection. METHOD: Patients treated with Chansu injection were divided randomly into 4 groups with 50 per group, control group, the magnesium sulfate group, phentolaminum group, and anisodamine group. Patients in the control group only received the routine nursing treatment, and patients in the various experiment group received different interventions. The comparison was made in the morbidity and the starting time of occurrence of phlebitis, the severity of pain, duration of pain. RESULT: The morbidity of phlebitis was 8%, 8%, 6% respectively. The starting time of phlebitis occurrence was (21 +/- 9.31) , (22.34 +/- 10.15), (20.19 +/- 11.23) h, respectively. The NRS of pain was (4. 15 +/- 1.03), (3.26 +/- 1.17), (4.32 +/- 1.36), respectively. The duration time of pain was (4.05 +/- 1.21), (3.37 +/- 1.17), (3.19 +/- 1.67) d, respectively. In control group, the morbidity of phlebitis, the starting time of occurrence of phlebitis, the severity of pain, duration of pain was 24%, (17 +/- 6.32) h, (6.58 +/- 1.29), (5.32 +/- 1.12) d, respectively. As compared with the control group, a significance difference was found between every group in three test groups and control group respectively (P<0.05). CONCLUSION: The morbidity and the starting time of occurrence of phlebitis, the severity of pain, duration of pain was significantly reduced respectively by external appication of magnesium sulfate, anisodamine, and intravenous drip infusion of phentolaminum.

The treatment of preeclampsia in a rat model employing Digibind.

Preeclampsia (PE) is a disorder that results in significant fetomaternal morbidity and mortality with yet no definitive pharmacological intervention. It involves the development of de novo hypertension and proteinuria after 20 weeks of pregnancy. All too often, intrauterine growth restriction (IUGR) occurs. Evidence has accrued that implicates the cardiac glycosides (the cardenolides and the bufadienolides) as potentially involved in the pathophysiology of PE. These compounds act by inhibiting Na(+)/K(+) ATPase. Digibind (digoxin immune Fab) antagonizes this action of the cardenolides. It also has cross-reactivity against the bufadienolides, including marinobufagenin. This study investigated the effects of Digibind in a rat model of PE. We induced a syndrome in rats, which includes many of the phenotypic characteristics of human PE. Digibind, in escalating doses, was given on days 10 to 20 of pregnancy. Digibind produced significant lowering of the blood pressure and reduced proteinuria in our rat model of PE. However, it also did not avert IUGR. In view of these findings, in our experimental model of human PE, further studies in the quest for effective treatment of PE need to focus on pharmaceuticals that can remedy the syndrome without compromising the fetus.

Efficacy and safety of gemcitabine-oxaliplatin combined with huachansu in patients with advanced gallbladder carcinoma.

AIM: To evaluate the efficacy and safety of gemcitabine-oxaliplatin (GEMOX) combined with huachansu (cinobufagin) injection treatment in patients with locally advanced or metastatic gallbladder carcinoma (GBC), and to assess the quality of life (QOL) of such patients. METHODS: Twenty-five patients with locally advanced or metastatic GBC were treated with intravenous gemcitabine (1000 mg/m2) over 30 min on days 1 and 8, 2 h infusion of oxaliplatin (120 mg/ m2) on day 1, and 2-3 h infusion of huachansu (20 mL/ m2) on days -3-11, every 3-4 wk. Treatment was continued until occurrence of unacceptable toxicity or disease progression. QOL of patients was assessed by the EORTC QLQ-C30 at baseline, at the end of the first, third and sixth chemotherapy cycles, and 1 mo after the treatment. RESULTS: Among the 25 patients with a median age of 64 years (range 42-78 years), 23 were evaluable in the study. A total of 137 cycles of therapy were performed and the median cycle was 5 (range 1-8) per patient. Out of the 23 patients whose response could be evaluated, 8 partial responses (PR) were observed (34.8%), while 7 patients (30.4%) demonstrated a stable disease (SD). The disease control rate was 65.2%. Progression of cancer was observed in 8 (34.8%) patients. The median progression-free and overall survival time was 5.8 mo (95% CI: 4.5-7.1 mo) and 10.5 mo, respectively. The therapy was well tolerated, with moderate myelosuppression as the main toxicity. Anemia grade 2 was seen in 16.0%, neutropenia grade 3 in 8.0% and thrombocytopenia grade 3 in 24.0% of patients, respectively. Non-hematologic toxicity ranged from mild to moderate. No death occurred due to toxicity. The QOL of patients was improved after chemotherapy, and the scores of QOL were increased by 10 to 20 points. CONCLUSION: GEMOX combined with huachansu (cinobufagin) injection is well tolerated, effective, thus improving the QOL of patients with advanced GBC.

Rapid detection of cardioactive bufalin toxicity using fluorescence polarization immunoassay for digitoxin.

Intoxication caused by digitalis-like substances after ingestion of cooked toad soup has been reported. Bufalin, a cardioactive compound, is found in toad. Bufalin is also found in many Chinese medicines. Earlier reports demonstrated cross reactivity of bufalin with fluorescence polarization immunoassay for digoxin. In this report, the authors demonstrated a significantly higher cross reactivity of bufalin with the fluorescence polarization assay for digitoxin. They supplemented aliquots of normal plasma that had various concentrations of bufalin (1 to 50 micrograms/ml) from a local blood bank and measured apparent digitoxin concentrations using fluorescence polarization immunoassay and chemiluminescent assays (ACS digitoxin) for digitoxin. They measured apparent digoxin and digitoxin concentrations using fluorescence polarization, microparticle enzyme immunoassay, and chemiluminescent assays for digitoxin. They observed apparent digitoxin or digoxin concentrations in sera supplemented with bufalin only with the fluorescence polarization assays. For example, the apparent digitoxin concentration observed in a serum supplemented with 25 ng/ml of bufalin was 24.3 ng/ml of digitoxin equivalent. The apparent digoxin concentration observed in the same specimen was 1.33 ng/ml digoxin equivalent. Bufalin caused positive interference in serum digoxin or digitoxin measurements in specimens containing digoxin or digitoxin when concentrations were measured by fluorescence polarization assays. In contrast, bufalin lowered the measured digoxin concentrations in serum pools containing digoxin when digoxin concentrations were measured by the microparticle enzyme immunoassay. The authors conclude that bufalin toxicity can be rapidly detected by the fluorescence polarization assay for digitoxin.