digoxin and oleandrin

In the present study, we investigated the cardioactive glycosides oleandrin and ouabain, and compared them to digoxin in a model of cardiotoxicity induced by doxorubicin. Adult rats were distributed into four experimental groups. Each group was challenged with a single intraperitoneal application of doxorubicin at a dose of 12 mg/kg. Then, they were treated with saline solution and the glycosides oleandrin, ouabain, and digoxin at a dose of 50 µg/kg, for 7 days. They underwent echocardiography, electrocardiography, hematologic, biochemical tests, and microscopic evaluation of the heart. All animals presented congestive heart failure, which was verified by a reduction in the ejection fraction. Oleandrin and digoxin were able to significantly reduce (p < 0.05) the eccentric remodeling caused by doxorubicin. Oleandrin and digoxin were significantly lower (p < 0.05) than the control group in maintaining systolic volume and left ventricular volume in diastole. Other parameters evaluated did not show significant statistical differences. All animals showed an increase in erythrocyte count, and an increase in the duration of the QRS complex on the ECG and myocardial necrosis at the histopathological analysis. It is concluded that the glycosides oleandrin, ouabain, and digoxin in the used dosage do not present therapeutic potential for the treatment of congestive heart failure caused by doxorubicin.

Topics: Animals; Cardenolides; Cardiac Glycosides; Cardiotonic Agents; Cardiotoxicity; Digoxin; Disease Models, Animal; Doxorubicin; Heart Failure; Ouabain; Rats, Wistar; Recovery of Function; Stroke Volume; Ventricular Function, Left; Ventricular Remodeling

This is a case of voluntary ingestion of Nerium oleander leaves in an adolescent requiring the use of atropine and emergency chartering of antidigoxin antibodies (Digifab®) due to the difficulty of assessing oleandrin level and associated toxicity. Upon hospital admission, a digoxinemia was performed (0.44μg/mL) and the presence of oleandrine was detected. Oleandrin levels at toxic levels may be suspected by a measure of blood digoxin and explain the patient's clinical signs, which could adapt the therapeutic management.

Topics: Adolescent; Cardenolides; Digoxin; Humans; Nerium; Plant Leaves

Topics: Animals; Antioxidants; Cardenolides; Cardiotoxicity; Digoxin; Dose-Response Relationship, Drug; Heart; Heart Diseases; Heart Rate; Male; Myocytes, Cardiac; Necrosis; Ouabain; Oxidative Stress; Rats, Wistar; Reactive Oxygen Species; Ventricular Remodeling

Topics: Aged; Atrial Fibrillation; Cardenolides; Digoxin; Electrocardiography; Female; Foodborne Diseases; Humans

Oleander interferes with serum digoxin measurements using various immunoassays. The potential interference of oleander and its active ingredient, oleandrin, with a relatively new homogenous sequential chemiluminescent digoxin assay based on luminescent oxygen channeling technology (LOCI digoxin assay, Siemens Diagnostics) has not been previously reported.. Aliquots of a digoxin-free serum pool were supplemented with increasing concentrations of oleandrin, or with oleander extract, followed by measuring the apparent digoxin concentrations using the LOCI digoxin assay using Vista 1500 analyzer. Mice were fed oleandrin or oleander extract, and their blood digoxin levels at 1 and 2 h were measured with the LOCI digoxin assay. In addition, two digoxin serum pools were prepared by combining sera of patients receiving digoxin; aliquots of both pools were supplemented with oleandrin or oleander extract and digoxin concentrations were again measured. Attempts to overcome this interference were made by measuring free digoxin concentration using a third digoxin pool.. Significant apparent digoxin concentrations were observed after supplementing aliquots of the drug-free serum pool with oleandrin or oleander extract. Mice fed with oleandrin or oleander extract also showed apparent digoxin levels 1 and 2 h after feeding. Digoxin values were also falsely lower or elevated (bidirectional interference) when aliquots of digoxin serum pools were further supplemented with oleandrin or oleander extract depending on concentration; this interference was not eliminated by free digoxin monitoring.. Oleandrin interferes with LOCI digoxin assay.

Topics: Animals; Cardenolides; Digoxin; Humans; Luminescent Measurements; Mice; Nerium; Plant Extracts

Cardiac glycosides of plant origin are implicated in toxic ingestions that may result in hospitalization and are potentially lethal. The utility of commonly available digoxin serum assays for detecting foxglove and oleander ingestion has been demonstrated, but no studies have evaluated the structurally similar convallatoxin found in Convallaria majalis (lily of the valley) for rapid laboratory screening, nor has digoxin immune Fab been tested as an antidote for this ingestion.. We aimed to (1) evaluate multiple digoxin assays for cross-reactivity to convallatoxin, (2) identify whether convallatoxin could be detected in vivo at clinically significant doses, and (3) determine whether digoxin immune Fab could be an effective antidote to convallatoxin.. Cross-reactivities of purified convallatoxin and oleandrin with five common digoxin immunoassays were determined. Serum from mice challenged with convallatoxin was tested for apparent digoxin levels. Binding of convallatoxin to digoxin immune Fab was determined in vitro.. Both convallatoxin and oleandrin were detectable by a panel of commonly used digoxin immunoassays, but cross-reactivity was variable between individual assays. We observed measurable apparent digoxin levels in serum of convallatoxin intoxicated mice at sublethal doses. Convallatoxin demonstrated no binding by digoxin immune Fab.. Multiple digoxin immunoassays detect botanical cardiac glycosides including convallatoxin and thus may be useful for rapid determination of severe exposures, but neutralization of convallatoxin by digoxin immune Fab is unlikely to provide therapeutic benefit.

Topics: Animals; Animals, Outbred Strains; Cardenolides; Cardiotonic Agents; Convallaria; Cross Reactions; Digoxin; Dose-Response Relationship, Drug; Female; Immunoassay; Immunoglobulin Fab Fragments; Lethal Dose 50; Mice; Plant Poisoning; Poisoning; Strophanthins; Vasodilator Agents

Nerium oleander is a very popular urban ornamental plant in Europe, but it is also extremely dangerous because it contains several types of glycosides, accidental ingestion of which can cause cardiac arrhythmias and even deaths. The rarity of such cases makes it difficult to think of oleander poisoning without evidences that suggest this possibility as the cause of the unexpected death. This report concerns the discovery of the bodies of 2 young people, a man and a woman, in a forest in conditions of extreme malnutrition. Medicolegal investigations showed neither pathologic nor traumatic causes of death, but the presence of vegetal remains in the stomach was noticed. A common toxicological analysis resulted negative, but the implementation of more detailed investigations showed the presence of digoxin in the blood of both cadavers, excluding the possibility of a pharmaceutical provenience of digoxin, this laboratory result was interpreted as evidence of ingestion of oleander, which contains oleandrine, the cross reaction of which with digoxin is widely described in the literature. Identification of the 2 subjects, which occurred after 4 years, strengthened the hypothesis of accidental poisoning by oleander because it was ascertained that the 2 young people were vegans--extreme vegetarians who reject the ingestion of foods of animal origin and live by eating only what they find in nature.

Topics: Adult; Cardenolides; Cardiac Glycosides; Digoxin; Female; Forensic Toxicology; Gastrointestinal Contents; Humans; Male; Nerium

Cardiac glycosides have been reported to exhibit cytotoxic activity against several different cancer types, but studies against colorectal cancer are lacking. In a screening procedure aimed at identifying natural products with activity against colon cancer, several cardiac glycosides were shown to be of interest, and five of these were further evaluated in different colorectal cancer cell lines and primary cells from patients. Convallatoxin (1), oleandrin (4), and proscillaridin A (5) were identified as the most potent compounds (submicromolar IC50 values), and digitoxin (2) and digoxin (3), which are used in cardiac disease, exhibited somewhat lower activity (IC50 values 0.27-4.1 microM). Selected cardiac glycosides were tested in combination with four clinically relevant cytotoxic drugs (5-fluorouracil, oxaliplatin, cisplatin, irinotecan). The combination of 2 and oxaliplatin exhibited synergism including the otherwise highly drug-resistant HT29 cell line. A ChemGPS-NP application comparing modes of action of anticancer drugs identified cardiac glycosides as a separate cluster. These findings demonstrate that such substances may exhibit significant activity against colorectal cancer cell lines, by mechanisms disparate from currently used anticancer drugs, but at concentrations generally considered not achievable in patient plasma.

Topics: Antineoplastic Agents; Antineoplastic Combined Chemotherapy Protocols; Camptothecin; Cardenolides; Colonic Neoplasms; Digitoxin; Digoxin; Drug Screening Assays, Antitumor; HT29 Cells; Humans; Irinotecan; NF-kappa B; Proscillaridin; Strophanthins

Despite known toxicity of oleander, this product is used in herbal preparations. Oleander interferes with various digoxin immunoassays. It is possible that a person taking digoxin also may take oleander-containing herbal products, and digoxin immunoassays interfering with oleander cannot be used for therapeutic monitoring of digoxin. Recently, Bayer Diagnostics introduced a new enzyme-linked chemiluminescent immunosorbent digoxin assay for application on the ADVIA IMS System (ECLIA-digoxin). We studied potential interference of oleander with this new digoxin assay and found that this assay is virtually free from oleander interference. When aliquots of drug-free serum pools were supplemented with ethyl alcohol extract of oleander leaf or pure oleandrin standard, we observed significant apparent digoxin concentration when measured by the fluorescence polarization immunoassay (FPIA) but minimal digoxin-like immunoreactivity using the ECLIA digoxin assay. Because cross-reactivity should be studied in the presence of primary analyte, we prepared 2 serum pools using sera from patients receiving digoxin. Then aliquots of first digoxin pool were supplemented with oleandrin standard and aliquots of second digoxin pool with oleander extract. We observed significant increases in apparent digoxin concentration in the presence of both oleandrin and oleander extract using the FPIA. However, we observed no statistically significant change in digoxin concentration when ECLIA digoxin assay was used, indicating that this assay is virtually free from oleander interference.

Topics: Cardenolides; Clinical Laboratory Techniques; Digoxin; Enzyme-Linked Immunosorbent Assay; Humans; Nerium; Reproducibility of Results

Accidental poisoning from oleander leaf or oleander tea can be life threatening. The authors studied the effectiveness of activated charcoal and equilibrium dialysis in removing oleander leaf extract and commercially available oleandrin as well as oleandrigenin, the active components of oleander plant, from human serum. Oleander leaf extract was prepared in distilled water and drug-free serum was supplemented with the extract. Then serum was treated with activated charcoal at room temperature and an aliquot was removed at 0 minutes, 10 minutes, 20 minutes, and finally 30 minutes to study the presence of oleander extract by measuring the apparent digoxin concentration using the FPIA for digoxin. The authors observed effective removal of oleander extract by activated charcoal. When the authors supplemented other drug-free serum pools with pure oleandrin or oleandrigenin and then subsequently treated them with activated charcoal, the authors observed complete removal of digoxin-like immunoreactivity at the end of 30 minutes' treatment. When drug-free serum pool supplemented with either oleander leaf extract, oleandrin, or oleandrigenin was passed through a small column packed with activated charcoal, the authors observed almost no apparent digoxin concentration following the passage through the column indicating that activated charcoal is very effective in removing oleander from human serum in vitro. In contrast, when serum pools containing either oleander leaf extract or oleandrin were subjected to equilibrium dialysis against phosphate buffer at pH 7.4, the authors observed no significant reduction in apparent digoxin concentration even after 24 hours. The authors conclude that activated charcoal is effective but equilibrium dialysis is ineffective in removing oleander leaf extract from human serum.

Topics: Cardenolides; Charcoal; Confidence Intervals; Dialysis; Digoxin; Humans; Nerium; Plant Extracts; Plant Leaves

Cardiac glycosides are used clinically to increase contractile force in patients with cardiac disorders. Their mechanism of action is well established and involves inhibition of the plasma membrane Na+/K+-ATPase, leading to alterations in intracellular K+ and Ca(2+) levels. Here, we report that the cardiac glycosides oleandrin, ouabain, and digoxin induce apoptosis in androgen-independent human prostate cancer cell lines in vitro. Cell death was associated with early release of cytochrome c from mitochondria, followed by proteolytic processing of caspases 8 and 3. Oleandrin also promoted caspase activation, detected by cleavage poly(ADP-ribose) polymerase and hydrolysis of a peptide substrate (DEVD-pNA). Comparison of the rates of apoptosis in poorly metastatic PC3 M-Pro4 and highly metastatic PC3 M-LN4 subclones demonstrated that cell death was delayed in the latter because of a delay in mitochondrial cytochrome c release. Single-cell imaging of intracellular Ca(2+) fluxes demonstrated that the proapoptotic effects of the cardiac glycosides were linked to their abilities to induce sustained Ca(2+) increases in the cells. Our results define a novel activity for cardiac glycosides that could prove relevant to the treatment of metastatic prostate cancer.

Topics: Adenocarcinoma; Apoptosis; Calcium; Cardenolides; Cardiac Glycosides; Cardiotonic Agents; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Separation; Cytochrome c Group; Digoxin; DNA Fragmentation; Dose-Response Relationship, Drug; Flow Cytometry; Humans; Male; Myocardium; Ouabain; Poly(ADP-ribose) Polymerases; Prostatic Neoplasms; Time Factors; Tumor Cells, Cultured

The microparticle enzyme immunoassay (MEIA for digoxin (Abbott Laboratories, Abbott Park, Ill) requires no sample pretreatment and is widely used in clinical toxicology laboratories for monitoring serum digoxin concentrations. One advantage of the new MEIA is the lower cross-reactivities with such cross-reactants as digitoxin, oleandrin, and bufalin compared with the fluorescence polarization immunoassay (FPIA)for digoxin. Digitoxin, oleandrin, and bufalin showed positive cross-reactivity with MEIA and FPIAs for digoxin in the absence of the primary analyte, digoxin. A surprising finding was that digoxin concentrations were falsely decreased by these cross-reactants when serum pools containing digoxin were supplemented with various concentrations of these cross-reactants and when digoxin concentrations were measured by the MEIA. In contrast, digoxin concentrations were falsely elevated when measured by the FPIA. For example, when a serum pool containing 2.15 nmol/L of digoxin was supplemented with 129.5 nmol/L of bufalin, the apparent digoxin concentrations were 1.45 nmol/L with the MEIA and 3.00 nmol/L with the FPIA. Taking the advantage of only 25% protein binding of digoxin and more than 95% protein binding of digitoxin and bufalin, we demonstrated that monitoring free digoxin instead of total digoxin eliminated negative interference of digoxin by these cross-reactants in the MEIA and positive interference in the FPIA. Although oleandrin is also strongly bound to serum protein, high concentrations of oleandrin still modestly affect the free digoxin assay for both MEIA and FPIAs.

Topics: Bufanolides; Cardenolides; Cardiac Glycosides; Cardiotonic Agents; Cross Reactions; Digitoxin; Digoxin; False Positive Reactions; Fluorescence Polarization Immunoassay; Humans; Immunoenzyme Techniques; Microspheres

Oleandrin plant poisoning is common in children and the plant extract is used in Chinese medicines. The toxicity is due to oleandrin and the deglycosylated metabolite oleandrigenin. Bufalin and cinobufotalin (toad cardiac toxins) are also widely used in Chinese medicines like Chan SU, and Lu-Shen -WU. Severe toxicity from bufalin after consumption of toad soup has been reported. Taking advantage of structural similarities of these toxins with digitoxin, we demonstrated that these compounds can be rapidly detected in blood by the fluorescence polarization immunoassay for digitoxin. The cross reactivities of these compounds with digoxin assay were much lower. For example, when a drug free serum was supplemented with 10 microg/ml of oleandrin, we observed 127.7 ng/ml of digitoxin equivalent but only 2.4 ng/ml of digoxin equivalent concentration. Digibind neutralized all cardiac toxins studied as evidenced by significant fall of free concentrations. When aliquots of serum pool containing 50.0 microg/ml of oleandrin were supplemented with 0, 10.0, 25.0, 50.0, 100, and 200 microg/ml of digibind, the mean free concentrations were 30.6, 23.3, 16.0, 10.7, 7.8 and 5.5 microg/ml respectively. Similarly, with 50.0 microg/ml of oleandrigenin (total concentration: 36.2 ng/ml), the free concentration was 14.5 ng/ml digitoxin equivalent in the absence of digibind and 5.4 ng/ml in the presence of 200 microg/ml of digibind. In another specimen containing 500 ng/ml bufalin (total concentration: 156.9 ng/ml), the free concentration was 8.6 ng/ml in the absence of digibind and none detected in the presence of 100.0 microg/ml digibind. Because such neutralization may also occur in vivo, digibind may be useful in treating patients exposed to these toxins.

Topics: Bufanolides; Cardenolides; Cardiotonic Agents; Chromatography, High Pressure Liquid; Cross Reactions; Digitoxin; Digoxin; Humans; Immunoassay; Immunoglobulin Fab Fragments; Mass Spectrometry; Neutralization Tests

Poisoning from the oleander plant is common. Taking advantage of the high cross-reactivity of oleandrin, the major cardiac glycoside found in the oleander plant, we demonstrated that the serum digitoxin assay can be successfully used for the rapid diagnosis of oleander poisoning. Digitoxin is rarely used for treatment of cardiac disorders in the United States and has a therapeutic range of 19.7 to 39.3 nmol/L. In a typical oleander poisoning, serum oleandrin concentrations may reach 174 mmol/L or more. A serum specimen supplemented with 174 mmol/L of oleandrin containing no digitoxin showed an apparent digitoxin concentration of 1,272.1 nmol/L, a very high value compared with the range of the serum digitoxin assay, which is 2.6 to 104.8 nmol/L. Moreover, the response of the serum digitoxin assay with serum specimens containing various concentrations of oleandrin (and no digitoxin) is linear. Therefore, the oleandrin concentration in serum can be calculated from the apparent digitoxin concentration to access the severity of poisoning. Recently, the usefulness of the digoxin-specific Fab antibody fragment in the treatment of oleander poisoning has been described; however, no laboratory test was performed to demonstrate the progress of therapy. We demonstrated that the digoxin-specific Fab antibody can bind oleandrin in vitro, thus reducing the pharmacologically active free oleandrin. Because Fab and oleandrin bound to Fab are absent in the protein-free ultrafiltrates, monitoring the activity of free oleandrin in the ultrafiltrates can be used for monitoring the effectiveness of therapy.

Topics: Cardenolides; Cardiac Glycosides; Cross Reactions; Digitoxin; Digoxin; Fluorescence Polarization; Humans; Immunoassay; Immunoglobulin Fab Fragments; Plants, Toxic

A case is presented of cardiac glycoside poisoning in a 1-year-old patient from the plant Nerium oleander (common oleander). The patient had bradycardia, vomiting, altered level of consciousness, and no history of ingestion. Antibody-based digoxin assays may cross-react with other cardiac glycosides nonquantitatively. Chromatographic techniques can be used in the specific diagnosis.

Topics: Animals; Anti-Arrhythmia Agents; Bradycardia; Cardenolides; Chromatography, High Pressure Liquid; Cross Reactions; Digoxin; False Positive Reactions; Glycosides; Humans; Immunoassay; Infant; Male; Plant Poisoning; Vomiting

Ingestion of oleander plant, containing the cardiac glycoside oleandrin, has been reported to induce fatal poisonings. Derivatives of oleandrin are structurally similar to digoxin. We investigated the cross-reactivities of oleandrin and its aglycone metabolite, oleandrigenin, in several commercially available digoxin immunoassays; assessed their ability to inhibit Na,K-ATPase catalytic activity; and measured their binding to proteins in serum. As assayed with ACS:180, Stratus, RIA, On-Line, and TDx digoxin assays, oleandrin at 100 micromol/L in digoxin-free serum gave apparent digoxin values of 0, 0.83, 2.24, 2.37, and 5.34 nmol/L, respectively, whereas oleandrigenin at that concentration gave results of 0, 0.52, 0.77, 4.94, and 1.40 nmol/L. Study of Na,K-ATPase inhibition showed IC50 values (micromol/L) of 0.22 for ouabain, 0.62 for oleandrin, 1.23 for oleandrigenin, and 2.69 for digoxin. At 25 degrees C, 96% of oleandrin and 48% of oleandrigenin were bound to serum proteins. Because detection of oleandrin and oleandrigenin by digoxin immunoassays is variable between assays as well as between congeners, assessment of cross-reactivity is warranted for each assay. The inhibition of Na,K-ATPase by oleandrin and oleandrigenin confirms that they likely exert their toxic effects through inhibition of sodium pump activity. In cases of digitalis-like poisoning with suspicion of oleander ingestion, a combination of digoxin immunoassays may be useful to effectively rule out the presence of oleander.

Topics: Blood Proteins; Cardenolides; Cardiac Glycosides; Digoxin; Enzyme Inhibitors; Humans; Immunoassay; Sensitivity and Specificity; Sodium-Potassium-Exchanging ATPase

Two distinct spontaneous variants of the murine anti-digoxin hybridoma 26-10 were isolated by fluorescence-activated cell sorting for reduced affinity of surface antibody for antigen. Nucleotide and partial amino acid sequencing of the variant antibody variable regions revealed that 1 variant had a single amino acid substitution: Lys for Asn at heavy chain position 35. The second variant antibody had 2 heavy chain substitutions: Tyr for Asn at position 35, and Met for Arg at position 38. Mutagenesis experiments confirmed that the position 35 substitutions were solely responsible for the markedly reduced affinity of both variant antibodies. Several mutants with more conservative position 35 substitutions were engineered to ascertain the contribution of Asn 35 to the binding of digoxin to antibody 26-10. Replacement of Asn with Gln reduced affinity for digoxin 10-fold relative to the wild-type antibody, but maintained wild-type fine specificity for cardiac glycoside analogues. All other substitutions (Val, Thr, Leu, Ala, and Asp) reduced affinity by at least 90-fold and caused distinct shifts in fine specificity. The Ala mutant demonstrated greatly increased relative affinities for 16-acetylated haptens and haptens with a saturated lactone. The X-ray crystal structure of the 26-10 Fab in complex with digoxin (Jeffrey PD et al., 1993, Proc Natl Acad Sci USA 90:10310-10314) reveals that the position 35 Asn contacts hapten and forms hydrogen bonds with 2 other contact residues. The reductions in affinity of the position 35 mutants for digoxin are greater than expected based upon the small hapten contact area provided by the wild-type Asn. We therefore performed molecular modeling experiments which suggested that substitution of Gln or Asp can maintain these hydrogen bonds whereas the other substituted side chains cannot. The altered binding of the Asp mutant may be due to the introduction of a negative charge. The similarities in binding of the wild-type and Gln-mutant antibodies, however, suggest that these hydrogen bonds are important for maintaining the architecture of the binding site and therefore the affinity and specificity of this antibody. The Ala mutant eliminates the wild-type hydrogen bonding, and molecular modeling suggests that the reduced side-chain volume also provides space that can accommodate a congener with a 16-acetyl group or saturated lactone, accounting for the altered fine specificity of this antibody.

Topics: Amino Acid Sequence; Animals; Antibodies, Monoclonal; Antibody Specificity; Base Sequence; Binding Sites; Cardenolides; Cardiac Glycosides; Crystallography, X-Ray; Digoxin; DNA; Genetic Variation; Hybridomas; Immunoglobulin Heavy Chains; Mice; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed

An elderly woman allegedly ingested oleander leaves and died. Ventricular arrhythmias and asystole were unresponsive to cardiopulmonary resuscitation, pharmacologic agents, and cardioversion. The patient, who had no access to digoxin, had an initial serum digoxin concentration of 5.8 ng/mL. Cross-reactivities between oleander extract and pure oleandrin and digoxin in the digoxin radioimmunoassay were 100:1 and 29,000:1, respectively. We postulate that glycosides in oleander leaves produced the elevated serum digoxin concentration. Based on an assumed volume of distribution of the oleander glycosides of 1 L/kg, the calculated lethal dose absorbed by our patient was 200 times greater than lethal doses in several animal species and corresponded to the absorption of 4 g of oleander leaves.

Topics: Aged; Cardenolides; Cross Reactions; Digoxin; Female; Heart Arrest; Humans; Plant Extracts; Plant Poisoning; Plants, Medicinal; Radioimmunoassay; Ventricular Fibrillation

Topics: Cardenolides; Digitoxin; Digoxin; Nerium; Ouabain; Research