Oleander toxicity: an examination of human and animal toxic exposures

Management of yellow oleander poisoning

BACKGROUND

Poisoning due to deliberate self-harm with the seeds of yellow oleander (Thevetia peruviana) results in significant morbidity and mortality each year in South Asia. Yellow oleander seeds contain highly toxic cardiac glycosides including thevetins A and B and neriifolin. A wide variety of bradyarrhythmias and tachyarrhythmias occur following ingestion. Important epidemiological and clinical differences exist between poisoning due to yellow oleander and digoxin; yellow oleander poisoning is commonly seen in younger patients without preexisting illness or comorbidity. Assessment and initial management. Initial assessment and management is similar to other poisonings. No definite criteria are available for risk stratification. Continuous ECG monitoring for at least 24 h is necessary to detect arrhythmias; longer monitoring is appropriate in patients with severe poisoning. Supportive care. Correction of dehydration with normal saline is necessary, and antiemetics are used to control severe vomiting. Electrolytes. Hypokalemia worsens toxicity due to digitalis glycosides, and hyperkalemia is life-threatening. Both must be corrected. Hyperkalemia is due to extracellular shift of potassium rather than an increase in total body potassium and is best treated with insulin-dextrose infusion. Intravenous calcium increases the risk of cardiac arrhythmias and is not recommended in treating hyperkalemia. Oral or rectal administration of sodium polystyrene sulfonate resin may result in hypokalemia when used together with digoxin-specific antibody fragments. Unlike digoxin toxicity, serum magnesium concentrations are less likely to be affected in yellow oleander poisoning. The effect of magnesium concentrations on toxicity and outcome is not known. Hypomagnesaemia should be corrected as it can worsen cardiac glycoside toxicity. Gastric decontamination. The place of emesis induction and gastric lavage has not been investigated, although they are used in practice. Gastric decontamination by the use of single dose and multiple doses of activated charcoal has been evaluated in two randomized controlled trials, with contradictory results. Methodological differences (severity of poisoning in recruited patients, duration of treatment, compliance) between the two trials, together with differences in mortality rates in control groups, have led to much controversy. No firm recommendation for or against the use of multiple doses of activated charcoal can be made at present, and further studies are needed. Single-dose activated charcoal is probably beneficial. Activated charcoal is clearly safe. Arrhythmia management. Bradyarrhythmias are commonly managed with atropine, isoprenaline, and temporary cardiac pacing in severe cases, although without trial evidence of survival benefit, or adequate evaluation of possible risks. Accelerating the heart rate with atropine or beta-adrenergic agents theoretically increases the risk of tachyarrhythmias, and it has been claimed that atropine increases tachyarrhythmic deaths. Further studies are required. Tachyarrhythmias have a poor prognosis and are more difficult to treat. Lidocaine is the preferred antiarrhythmic; the role of intravenous magnesium is uncertain. Digoxin-specific antibody fragments. Digoxin-specific antibody fragments are effective in reverting life-threatening cardiac arrhythmias; prospective observational studies show a beneficial effect on mortality. High cost and lack of availability limit the widespread use of digoxin-specific antibody fragments in developing countries.

CONCLUSIONS

Digoxin-specific antibody fragments remain the only proven therapy for yellow oleander poisoning. Further studies are needed to determine the place of activated charcoal, the benefits or risks of atropine and isoprenaline, the place and choice of antiarrhythmics, and the effect of intravenous magnesium in yellow oleander poisoning.

A fatal case of oleandrin poisoning

The study presents a case of fatal poisoning with oleander leaves in an adult diabetic male. After repeated vomiting, and gastrointestinal distress the patient was admitted at the hospital with cardiac symptoms 1h after the ingestion. Urine samples were assayed immunochemically and by GC-MS for drugs of abuse and for general toxicological screen. Blood was analyzed for alcohol and volatiles by static head space GC-MS. Blood and oleander leaves were analyzed by LC-MS/MS for oleandrin and related compounds, the main cardiac glycosides of Nerium oleander. Oleandrin was detected by LC-MS/MS in the blood sample at a concentration of approximately 10 ng/ml. Another cardiac glycoside with pseudo-molecular ion of m/z 577, a likely structural isomer of oleandrin, was also detected in the blood and oleander leaves. However, by using the response as a function of concentration for oleandrin, this cardiac glycoside was roughly estimated at a concentration of approximately 10 ng/ml in the deceased blood. This would give a total fatal blood concentration of cardiac glycosides of about approximately 20 ng/ml in the deceased blood.

Toxicity in goats caused by oleander (Nerium oleander)

Cases of poisoning by oleander (Nerium oleander) were observed in several species, except in goats. This study aimed to evaluate the pathological effects of oleander in goats. The experimental design used three goats per group: the control group, which did not receive oleander and the experimental group, which received leaves of oleander (50 mg/kg/day) for six consecutive days. On the seventh day, goats received 110 mg/kg of oleander leaves four times at one-hourly interval. A last dose of 330 mg/kg of oleander leaves was given subsequently. After the last dose was administered, clinical signs such as apathy, colic, vocalizations, hyperpnea, polyuria, and moderate rumen distention were observed. Electrocardiogram revealed second-degree atrioventricular block. Death occurred on an average at 92 min after the last dosing. Microscopic evaluation revealed renal necrosis at convoluted and collector tubules and slight myocardial degeneration was observed by unequal staining of cardiomyocytes. Data suggest that goats appear to respond to oleander poisoning in a manner similar to other species.

Plant poisoning

Each year over 100,000 exposures to toxic plants are reported to poison centers throughout the United States. Most of these exposures are of minimal toxicity largely because of the fact that they involve pediatric ingestions, which are of low quantity. The more serious poisonings usually involve adults who have either mistaken a plant as edible or have deliberately ingested the plant to derive perceived medicinal or toxic properties. The plants within this manuscript have been chosen because they have been documented to cause fatalities or account for emergency medicine visits. In this discussion, plants are grouped by their toxins rather than on the basis of their taxonomy.

Therapeutic drug monitoring of digoxin: impact of endogenous and exogenous digoxin-like immunoreactive substances

Digoxin is a cardioactive drug with a narrow therapeutic range. Therapeutic drug monitoring is essential in clinical practice for efficacy as well as to avoid digoxin toxicity. Immunoassays are commonly used in clinical laboratories for determination of serum or plasma digoxin concentrations. Unfortunately, digoxin immunoassays are affected by both endogenous and exogenous compounds. Endogenous compounds are termed 'digoxin-like immunoreactive substances' (DLIS), which are found in elevated concentrations in volume-expanded patients. Exogenous compounds that interfere with digoxin assays are various drugs such as spironolactone, potassium canrenoate as well as Digibind (Fab fragment of antidigoxin antibody), which is used in treating life-threatening digoxin overdose. Moreover, various Chinese medicines such as Chan Su, Lu-Shen Wan and oleander-containing herbal preparations also interfere with serum digoxin measurements by immunoassays. Monitoring unbound (free) digoxin concentration may under certain circumstances eliminate such interferences. Clinicians should be aware of limitations of therapeutic drug monitoring of digoxin using immunoassays.

Pharmacokinetics of digoxin cross-reacting substances in patients with acute yellow Oleander (Thevetia peruviana) poisoning, including the effect of activated charcoal

Intentional self-poisonings with seeds from the yellow oleander tree (Thevetia peruviana) are widely reported. Activated charcoal has been suggested to benefit patients with yellow oleander poisoning by reducing absorption and/or facilitating elimination. Two recent randomized controlled trials (RCTs) assessing the efficacy of activated charcoal yielded conflicting outcomes in terms of mortality. The effect of activated charcoal on the pharmacokinetics of Thevetia cardenolides has not been assessed. This information may be useful for determining whether further studies are necessary. Serial blood samples were obtained from patients enrolled in an RCT assessing the relative efficacy of single-dose and multiple-dose activated charcoal (SDAC and MDAC, respectively) compared with no activated charcoal (NoAC). The concentration of Thevetia cardenolides was estimated with a digoxin immunoassay. The effect of activated charcoal on cardenolide pharmacokinetics was compared between treatment groups by determining the area under the curve for each patient in the 24 hours following admission, the 24-hour mean residence time, and regression lines obtained from serial concentration points, adjusted for exposure. Erratic and prolonged absorption patterns were noted in each patient group. The apparent terminal half-life was highly variable, with a median time of 42.9 hours. There was a reduction in 24-hour mean residence time and in the apparent terminal half-life estimated from linear regression in patients administered activated charcoal, versus the control group (NoAC). This effect was approximately equal in patients administered MDAC or SDAC. Activated charcoal appears to favorably influence the pharmacokinetic profile of Thevetia cardenolides in patients with acute self-poisoning and may have clinical benefits. Given the conflicting clinical outcomes noted in previous RCTs, these mechanistic data support the need for further studies to determine whether a particular subgroup of patients (eg, those presenting soon after poisoning) will benefit from activated charcoal.

Antidotes for acute cardenolide (cardiac glycoside) poisoning

BACKGROUND

Cardenolides are naturally occurring plant toxins which act primarily on the heart. While poisoning with the digitalis cardenolides (digoxin and digitoxin) are reported worldwide, cardiotoxicity from other cardenolides such as the yellow oleander are also a major problem, with tens of thousands of cases of poisoning each year in South Asia. Because cardenolides from these plants are structurally similar, acute poisonings are managed using similar treatments. The benefit of these treatments is of interest, particularly in the context of cost since most poisonings occur in developing countries where resources are very limited.

OBJECTIVES

To determine the efficacy of antidotes for the treatment of acute cardenolide poisoning, in particular atropine, isoprenaline (isoproterenol), multiple-dose activated charcoal (MDAC), fructose-1,6-diphosphate, sodium bicarbonate, magnesium, phenytoin and anti-digoxin Fab antitoxin.

SEARCH STRATEGY

We searched MEDLINE, EMBASE, the Controlled Trials Register of the Cochrane Collaboration, Current Awareness in Clinical Toxicology, Info Trac, www.google.com.au, and Science Citation Index of studies identified by the previous searches. We manually searched the bibliographies of identified articles and personally contacted experts in the field.

SELECTION CRITERIA

Randomised controlled trials where antidotes were administered to patients with acute symptomatic cardenolide poisoning were identified.

DATA COLLECTION AND ANALYSIS

We independently extracted data on study design, including the method of randomisation, participant characteristics, type of intervention and outcomes from each study. We independently assessed methodological quality of the included studies. A pooled analysis was not appropriate.

MAIN RESULTS

Two randomised controlled trials were identified, both were conducted in patients with yellow oleander poisoning. One trial investigated the effect of MDAC on mortality, the relative risk (RR) was 0.31 (95% confidence interval (CI) 0.12 to 0.83) indicating a beneficial effect. The second study found a beneficial effect of anti-digoxin Fab antitoxin on the presence of cardiac dysrhythmias at two hours post-administration; the RR was 0.60 (95% CI 0.44 to 0.81). Other benefits were also noted in both studies and serious adverse effects were minimal. Studies assessing the effect of antidotes on other cardenolides were not identified. One ongoing study investigating the activated charcoal for acute yellow oleander self-poisoning was also identified.

AUTHORS' CONCLUSIONS

There is some evidence to suggest that MDAC and anti-digoxin Fab antitoxin may be effective treatments for yellow oleander poisoning. However, the efficacy and indications of these interventions for the treatment of acute digitalis poisoning is uncertain due to the lack of good quality controlled clinical trials. Given pharmacokinetic differences between individual cardenolides, the effect of antidotes administered to patients with yellow oleander poisoning cannot be readily translated to those of other cardenolides. Unfortunately cost limits the use of antidotes such as anti-digoxin Fab antitoxin in developing countries where cardenolide poisonings are frequent. More research is required using relatively cheap antidotes which may also be effective.

Acute cattle intoxication from Nerium oleander pods

Seven outbreaks of acute intoxication from oleander (Nerium oleander) in cattle were reported in Northeast of Brazil. A total of 92 cattle were poisoned by oleander in 7 different herds; 57 animals died (67% of affected cattle). All cases reported here occurred during dry season. Two of the outbreaks resulted from offering oleander triturated and mixed with fodder. In the other cases, accidental ingestion of residual parts of oleander derived from pruning or cutting plants on grazing land were responsible. Clinical signs were diverse; the most common were locomotion disturbances, diarrhoea, depression and sudden death. Postmortem findings varied from no significant lesions to widespread haemorrhage. The presence of oleander leaves in the rumen was noted in all cases. The lack of information about the toxicity of oleanders was the main cause for the accident, which prompt us to stimulate wide divulgation of the common toxic plants.

Phase 1 trial of Anvirzel™ in patients with refractory solid tumors

Anvirzel is an aqueous extract of the plant Nerium oleander which has been utilized to treat patients with advanced malignancies. The current study reports a phase 1 trial to determine the maximum tolerated dose (MTD) and safety of Anvirzel in patients with advanced, refractory solid tumors. Patients were randomized to receive this agent by intramuscular injection at doses of 0.1, 0.2, 0.4 ml/m2/day with subsequent patients receiving 0.8 or 1.2 ml/m2/day sequentially. Eighteen patients were enrolled and completed at least one treatment cycle of three weeks. Most patients developed mild injection site pain (78%). Other toxicities included fatigue, nausea, and dyspnea. Traditional dose limiting toxicity was not seen, but the MTD was defined by injection volume as 0.8 ml/m2/day. No objective anti-tumor responses were seen. Anvirzel can be safely administered at doses up to 1.2 ml/m2/day, with the amount administered intramuscularly limited by volume. The recommended phase II dose level is 0.8 ml/m2/day.

The New Enzyme-Linked Immunosorbent Digoxin Assay on the ADVIA Integrated Modular System® is Virtually Free From Oleander Interference

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.

[Nerium oleander self poisoning treated with digoxin-specific antibodies]

A chronically depressed 44-year-old man was rescued by the French medicalised ambulance service four hours after the ingestion of Nerium oleander leaves in a suicide attempt. Cardiotoxicity was evidenced by the presence of bradycardia with mental confusion and vomiting. The patient was empirically treated in the prehospital phase with a single dose of digoxin-specific Fab antibody fragments (Digidot). In spite of this treatment, the patient presented a new episode of important bradycardia (25 b/minute). Thereafter, the patient's rhythm stabilized and neurological signs and vomiting resolved. The patient recovered uneventfully and was discharged from the intensive care unit two days later.

Determination of oleandrin in tissues and biological fluids by liquid chromatography-electrospray tandem mass spectrometry

A rapid LC-MS/MS method, using a triple-quadrupole/linear ion trap mass spectrometer, was developed for the quantitative determination of oleandrin in serum, urine, and tissue samples. Oleandrin, the major cardiac glycoside of oleander (Nerium oleander L.), was extracted from serum and urine samples with methylene chloride and from tissues with acetonitrile. The tissue extracts were cleaned up using Florisil solid-phase extraction columns. Six replicate fortifications of serum and urine at 0.001 microg/g (1 ppb) oleandrin gave average recoveries of 97% with 5% CV (relative standard deviation) and 107% with 7% CV, respectively. Six replicate fortifications of liver at 0.005 microg/g (5 ppb) oleandrin gave average recoveries of 98% with 6% CV. This is the first report of a positive mass spectrometric identification and quantitation of oleandrin in tissue samples from oleander intoxication cases. The sensitivity and specificity of the LC-MS/MS analysis enables it to be the method of choice for toxicological investigations of oleander poisoning.

Rapid Detection of Oleander Poisoning Using Digoxin Immunoassays

Oleander is an ornamental shrub that grows in the United States, Australia, India, Sri Lanka, China, and other parts of the world. All parts of the plant are poisonous because the presence of cardiac glycoside oleandrin. Despite its toxicity, oleander extract is used in folk medicines. Because of its structural similarity, oleandrin cross-reacts with the fluorescence polarization immunoassay (FPIA) for digoxin. We studied the potential of detecting oleandrin in serum using 5 common digoxin immunoassays (FPIA, MEIA, both from Abbott; Beckman digoxin assay on Synchron LX, Chemiluminescent assay, CLIA from Bayer Diagnostics) and a recently FDA-approved turbidimetric assay on the ADVIA 1650 analyzer (Bayer). Aliquots of drug-free and digoxin-like immunoreactive substances (DLIS)-free serum pools were supplemented with ethanol extract of oleander leaves or oleandrin (Sigma Chemicals) in amounts expected in vivo after severe overdose. We observed significant apparent digoxin concentration with FPIA, Beckman, and the new turbidimetric assay (1 mL drug-free serum supplemented with 5.0 microL of oleander extract: apparent digoxin 2.36 ng/mL by the FPIA, 0.32 ng/mL by the MEIA, 0.93 ng/mL by the Beckman, 0.82 ng/mL by the new turbidimetric assay). The CLIA showed no cross-reactivity. Similar observations were made when serum pools were supplemented with oleandrin. Because cross reactivity should be tested in the presence of the primary analyte, we supplemented serum pools prepared from patients receiving digoxin with oleander extract or oleandrin. The measured digoxin concentrations were falsely elevated with the FPIA, Beckman, and turbidimetric assays, the highest false elevation being observed with the FPIA. Surprisingly, apparent digoxin concentrations were falsely lowered when MEIA was used. Digibind neutralizes free apparent digoxin concentration in vitro in serum pools supplemented with oleander extract, and this effect can be measured by the FPIA. We conclude that FPIA is most sensitive to detect the presence of oleander in serum. In contrast, the CLIA (no cross-reactivity) should be used for monitoring digoxin in a patient receiving digoxin and self-medicated with a herbal remedy containing oleander.

A Rare Cause of Complete Heart Block After Transdermal Botanical Treatment for Psoriasis

We report the case of a 59-year-old man with a new 3 degrees AV block with a history of psoriasis. After implantation of a definitive DDDR pacemaker, the patient reported a transdermal self-medication with an extract of Nerium oleander for the treatment of his psoriasis. The pharmacological, epidemiological, and clinical features are discussed in brief.

Multiple-dose activated charcoal for treatment of yellow oleander poisoning: a single-blind, randomised, placebo-controlled trial

BACKGROUND

Deliberate self-poisoning with yellow oleander seeds is common in Sri Lanka and is associated with severe cardiac toxicity and a mortality rate of about 10%. Specialised treatment with antidigoxin Fab fragments and temporary cardiac pacing is expensive and not widely available. Multiple-dose activated charcoal binds cardiac glycosides in the gut lumen and promotes their elimination. We aimed to assess the efficacy of multiple-dose activated charcoal in the treatment of patients with yellow-oleander poisoning.

METHODS

On admission, participants received one dose of activated charcoal and were then randomly assigned either 50 g of activated charcoal every 6 h for 3 days or sterile water as placebo. A standard treatment protocol was used in all patients. We monitored cardiac rhythm and did 12-lead electocardiographs as needed. Death was the primary endpoint, and secondary endpoints were life-threatening cardiac arrhythmias, dose of atropine used, need for cardiac pacing, admission to intensive care, and number of days in hospital. Analysis was by intention to treat.

FINDINGS

201 patients received multiple-dose activated charcoal and 200 placebo. There were fewer deaths in the treatment group (five [2.5%] vs 16 [8%]; percentage difference 5.5%; 95% CI 0.6-10.3; p=0.025), and we noted difference in favour of the treatment group for all secondary endpoints, apart from number of days in hospital. The drug was safe and well tolerated.

INTERPRETATION

Multiple-dose activated charcoal is effective in reducing deaths and life-threatening cardiac arrhythmias after yellow oleander poisoning and should be considered in all patients. Use of activated charcoal could reduce the cost of treatment.

Activated charcoal is effective but equilibrium dialysis is ineffective in removing oleander leaf extract and oleandrin from human serum: monitoring the effect by measuring apparent digoxin concentration

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.

Murine pharmacokinetics and metabolism of oleandrin, a cytotoxic component of Nerium oleander

Pharmacokinetic studies of [3H]oleandrin, a cardiac glycoside component of Anvirzel, were conducted in mice after either an i.v. dose (40 micrograms/kg) or a p.o. dose (80 micrograms/kg). Oleandrin was rapidly absorbed after oral dosing (Cmax at 20 min) although the elimination half-life was longer (2.3 +/- 0.5 h) than that after i.v. dosing (0.4 +/- 0.1 h). The AUC0-infinity values obtained after i.v. and p.o. dosing were 24.6 +/- 11.1 and 14.4 +/- 4.3 (ng.h/ml), respectively, resulting in an oral bioavailability of approximately 30%. After i.v. administration, oleandrin concentration in liver was approximately twice that measured in heart or kidney tissue. Oleandrigenin, the aglycone of oleandrin, was also found in these tissues. At 5 min, > 60% of the total radioactivity in liver was due to oleandrin while 28% of the given dose was present as oleandrigenin. Twenty-four hours following injection, 8% of total radioactivity was excreted in urine and contained both oleandrigenin (4.4% of the injected dose) and oleandrin (1.9%). Sixty-six percent of injected radioactivity was found in feces and consisted of oleandrin and oleandrigenin in equal amounts. Uptake of oleandrin in brain after i.p. injection of oleandrin (3 mg/kg) or oleander extract (700 mg/kg) was examined. Measured by LC/MS/MS, oleandrin content in brain was higher following injection of extract than it was with an equivalent dose of oleandrin. The data suggest that components within oleander extract may enhance transport of oleandrin across the blood brain barrier.

Detecting organic toxins in possible fatal poisonings – a diagnostic problem

Two fatal cases are reported where there was strong circumstantial evidence of plant toxin ingestion. In only one case however was a low urine level of hyoscine detected (in keeping with a history of Datura sp. consumption). Fatal cases of plant toxin ingestion may be a problem for the laboratory given the wide range and rarity of certain plant poisons, and the limitation of standard screening. Identification of plant materials at the scene of suspected poisoning may be crucial in directing toxicological investigations.

Yellow oleander poisoning in Sri Lanka: outcome in a secondary care hospital

Cardiac toxicity after self-poisoning from ingestion of yellow oleander seeds is common in Sri Lanka. We studied all patients with yellow oleander poisoning (YOP) admitted to a secondary care hospital in north central Sri Lanka from May to August 1999, with the objective of determining the outcome of management using currently available treatment. Patients with bradyarrhythmias were treated with intravenous boluses of atropine and intravenous infusions of isoprenaline. Temporary cardiac pacing was done for those not responding to drug therapy. During the study period 168 patients with YOP were admitted to the hospital (male:female = 55:113). There were six deaths (2.4%), four had third-degree heart block and two died of undetermined causes. They died soon after delayed admission to the hospital before any definitive treatment could be instituted. Of the remaining 162 patients, 90 (55.6%) patients required treatment, and 80 were treated with only atropine and/or isoprenaline while 10 required cardiac pacing in addition. Twenty-five (14.8%) patients had arrhythmias that were considered life threatening (second-degree heart block type II, third-degree heart block and nodal bradycardia). All patients who were treated made a complete recovery. Only a small proportion of patients (17%) admitted with YOP developed life-threatening cardiac arrhythmias. Treatment with atropine and isoprenaline was safe and adequate in most cases.

Flavanone and flavonol glycosides from the leaves of Thevetia peruviana and their HIV-1 reverse transcriptase and HIV-1 integrase inhibitory activities

Two new flavanone glucosides, (2R)- and (2S)-5-O-beta-D-glucopyranosyl-7,4'-dihydroxy-3',5'-dimethoxyflavanone[pervianoside I (3), peruvianoside II(4)] and a new flavonol glycoside, quercetin 3-O-[beta-D-glucopyranosyl-(1-->2)-[alpha-L-rhamnopyranosyl-(1-->6)]-beta-D-galactopyranoside] (peruvianoside III, 13) were isolated from the leaves of Thevetia peruviana Schum., together with nine known flavonol glycosides and two known iridoid glucosides. The structures of all compounds were determined on the basis of chemical and spectroscopic methods. Their inhibitory effects against HIV-1 reverse transcriptase and HIV-1 integrase were also investigated.

Benefits, adverse effects and drug interactions of herbal therapies with cardiovascular effects

Because the use of herbal therapies in the U.S. is escalating, it is essential to be aware of clinical and adverse effects, doses and potential drug-herb interactions. A consumer poll in 1998 indicated that one-third of respondents use botanical remedies, and nearly one in five taking prescription medications also used herbs, high-dose dietary supplements or both. An estimated 15 million adults are at risk for potential adverse interactions involving prescription medications and herbs or vitamin supplements, yet most practicing physicians have little knowledge of herbal remedies or their effects. Herbal products are marketed without the proof of efficacy and safety that the Food and Drug Administration (FDA) requires of drugs. The Dietary Supplement and Health Education Act of 1994 allocates responsibility to manufacturers for ensuring safety and efficacy with no specific requirements to submit documentation. Manufacturers may state a product's physiologic effects but may not make claims for the treatment or cure of specific diseases. Consumers and practitioners have little information about product safety, contraindications, interactions or effectiveness and are reliant on manufacturers to provide accurate labeling. Recently, the growing number of foods with herbs has raised concerns at the FDA, which requires evidence that food additives are safe. Considering that the growing appeal of herbal remedies is likely to continue, physicians, particularly cardiologists, must become familiar with the available cardiovascular information on herbs. This review highlights the existing data on the efficacy, adverse effects and interactions for herbal therapies that impact on the cardiovascular system.

Effects of the sap of the common oleander Nerium indicum (Apocyanaceae) on male fertility and spermatogenesis in the oriental tobacco budworm Helicoverpa assulta (Lepidoptera, Noctuidae)

We investigated the effects of sap of the common oleander Nerium indicum (Apocyanaceae) on male fertility and spermatogenesis in the oriental tobacco budworm Helicoverpa assulta. We found that continuous feeding of oleander sap during the larval period significantly affects fertility in males but not in females. This effect was also induced by direct injection of oleander sap into the hemocoel of 2-day-old pupae. Histological analyses of developing testes following oleander injection revealed a developmental delay and progressively more severe morphological abnormalities in the later stages of development. The effects of oleander sap on spermatogenesis in H. assulta were associated with greatly reduced levels of the two major polyamines, spermidine and spermine, in testis compared with saline-injected controls. In contrast, levels of putrescine, which is a precursor of both spermidine and spermine, and the activities of the enzymes ornithine decarboxylase and arginine decarboxylase, which are involved in the biosynthesis of putrescine, were initially elevated following oleander injection, but subsequently failed to undergo the induction that normally occurs during late pupal development. The effects of oleander sap on spermidine and spermine levels could be the result of direct inhibition by chemical constituents of the oleander sap of one of the enzymes used in common in the conversions of putrescine to spermidine and spermidine to spermine; alternatively, these effects on polyamine metabolism could be secondary to the disruption of a more fundamental process in the developmental program guiding spermatogenesis in H. assulta.

LC/MS/MS analyses of an oleander extract for cancer treatment

An HPLC/MS/MS method has been developed for the characterization and quantification of the cardiac glycosides oleandrin, odoroside, neritaloside and the aglycone oleandrigenin, all contained in a patented-hot-water extract of Nerium oleander L (Anvirzel). Qualitative analysis of such extracts was achieved using a hybrid tandem quadrupole time-of-flight (QqTOF) mass spectrometer. Collision-induced dissociation (CID) mass spectra of oleandrin, oleandrigenin, odoroside, and neritaloside were obtained with greater than 5 ppm mass accuracy and resolution routinely in excess of 8000 (fwhm). The detection limit for oleandrin of 20 pg (injected) was realized when the precursor-to-product ion transition, m/z 577 --> 373, was monitored. We have also applied the analytical method to the determination of oleandrin, oleandrigenin, neritaloside, and odoroside in human plasma following an intramuscular injection of Anvirzel.

Anvirzel, an extract of Nerium oleander, induces cell death in human but not murine cancer cells

The purpose of this study was to examine the mechanism(s) and differential cell-killing effects of Anvirzel, an extract of oleander (Nerium oleander; family-Apocynaceae), and its derivative compound Oleandrin on human, canine and murine tumor cells. Cells received different concentrations of Anvirzel (1.0 ng/ml to 500 microg/ml) or Oleandrin (0.01 ng/ml to 50 microg/ml) in both continuously treated and pulse-treated/recovery cultures. The cytotoxicity of these compounds was then determined. Both Anvirzel and Oleandrin were able to induce cell killing in human cancer cells, but not in murine cancer cells; the cell-killing potency of Oleandrin was greater than that of Anvirzel. Canine oral cancer cells treated with Anvirzel showed intermediate levels of response, with some abnormal metaphases and cell death resulting from the treatment. From these results we conclude that Anvirzel and Oleandrin act in a species-specific manner, and while testing the effectiveness of a new compound for cancer treatment, one must use not only murine but a variety of cancer cells, including those of human origin.

Anti-digoxin Fab fragments in cardiotoxicity induced by ingestion of yellow oleander: a randomised controlled trial

BACKGROUND

Severe cardiac glycoside cardiotoxicity after ingestion of yellow oleander seeds is an important problem in rural areas of Sri Lanka. Currently, patients must be transferred to the capital for temporary cardiac pacing. We did a randomised controlled trial to investigate whether anti-digoxin Fab could reverse serious oleander-induced arrhythmias.

METHODS

After a preliminary dose-finding study, 66 patients who presented to hospital with a serious cardiac arrhythmia were randomised to receive either 1200 mg of anti-digoxin Fab or a saline placebo. A 12-lead electrocardiogram, 3 min rhythm strip, and blood sample for measurement of electrolytes and cardiac glycosides were taken before treatment and at 12 timepoints thereafter.

FINDINGS

34 patients received anti-digoxin Fab and 32 received placebo. The presenting arrhythmia had resolved completely after 2 h in 15 antibody-treated patients and two controls (p<0.001); 24 and five patients, respectively, were in sinus rhythm at 8 h (p<0.001). Kaplan-Meier analysis of time to first reversal showed a significant response to anti-digoxin Fab. The heart rate increased in cases, from 49.1 per min at baseline to 66.8 at 2 h, but not in controls (50.6 per min at baseline to 51.5; p<0.001). Mean serum potassium concentrations decreased from 4.9 mmol/L to 4.1 mmol/L at 2 h in cases; no such decrease occurred in controls.

INTERPRETATION

Anti-digoxin Fab fragments are a safe and effective treatment for serious cardiac arrhythmias induced by yellow oleander. Their use in small rural hospitals in Sri Lanka should minimise costly transfer of patients and reduce the numbers of deaths; however, further study will be required to confirm this reduction.

Toxicological studies on stem bark, leaf and seed kernel of yellow oleander (Thevetia peruviana)

A comparative study of the toxic effects of extracts from stem bark, leaf and seed kernel of yellow oleander (Thevetia peruviana) in albino rats was carried out. Male and female albino rats weighing 150-200 g were administered crude aqueous extracts of stem bark, leaf and seed kernel of the plant by intraperitoneal injection or exposed to baits prepared with the dry extracts of the plant parts. The control groups either received distilled water by injection, or were fed non-poisoned baits. Extracts from all the plant parts were toxic, and produced marked poisoning symptoms that culminated in death. Poisoning symptoms manifested earlier (10 min after treatment) in rats administered aqueous kernel extracts intraperitoneally as against 45 min to several hours in rats poisoned by ingestion of toxicant. Poisoning symptoms indicated serious cardiac, neuromotor and mental malfunctioning, and manifested as tachycardia, arrhythmia, paralysis, ataxia and disorientation. The lethal dose was lowest (507 mg/kg) with the concentrated aqueous kernel extract (CAKE), and highest (5700 mg/kg) with the bait formulated using 40% of the kernel meal - FKM(B). Rats treated by injection with aqueous kernel extract (AKE) died faster within 10 h, than those with the aqueous leaf or stem bark extracts that died after 260 h. No mortality or abnormal behavioural changes were observed among animals in the control groups.

Acute yellow oleander (Thevetia peruviana) poisoning: cardiac arrhythmias, electrolyte disturbances, and serum cardiac glycoside concentrations on presentation to hospital

OBJECTIVE

To describe the cardiac arrhythmias, electrolyte disturbances, and serum cardiac glycoside levels seen in patients presenting to hospital with acute yellow oleander (Thevetia peruviana) poisoning and to compare these with published reports of digitalis poisoning.

DESIGN

Case series.

SETTING

Medical wards of Anuradhapura District General Hospital, Sri Lanka, and coronary care unit of the Institute of Cardiology, National Hospital of Sri Lanka, Colombo, the national tertiary referral centre for cardiology.

PATIENTS

351 patients with a history of oleander ingestion.

MEASUREMENTS

ECG and blood sample analysis on admission.

RESULTS

Most symptomatic patients had conduction defects affecting the sinus node, the atrioventricular (AV) node, or both. Patients showing cardiac arrhythmias that required transfer for specialised management had significantly higher mean serum cardiac glycoside and potassium but not magnesium concentrations. Although there was considerable overlap between groups, those with conduction defects affecting both sinus and AV nodes had significantly higher mean serum cardiac glycoside levels.

CONCLUSIONS

Most of these young previously healthy patients had conduction defects affecting the sinus or AV nodes. Relatively few had the atrial or ventricular tachyarrhythmias or ventricular ectopic beats that are typical of digoxin poisoning. Serious yellow oleander induced arrhythmias were associated with higher serum cardiac glycoside concentrations and hyperkalaemia but not with disturbances of magnesium.

Multiresidue screen for cardiotoxins by two-dimensional thin-layer chromatography

A two-dimensional thin-layer chromatographic method was developed for the qualitative determination of the cardiotoxins oleandrin, gitoxin, digitoxin, gitoxigenin, and grayanotoxins I, II, and III in gastrointestinal contents (stomach, rumen, colon, and cecum contents), feces, and plant material. The cardiotoxins were extracted with dichloromethane. The extract was cleaned up by charcoal and reverse phase solid-phase extraction columns. Analysis was performed by two-dimensional thin-layer chromatography on silica gel plates and visualized by aluminum chloride followed by chloramine T spray. The method detection limits were 0.05 microg/g for oleandrin, 0.1 microg/g for gitoxin, and 0.2 microg/g for the other toxicants in gastrointestinal contents and feces and were 5 times higher in plant material. Four replicate fortifications of bovine rumen contents, bovine feces, and alfalfa at these levels were all well recovered. The diagnostic utility of the method was tested by analyzing samples submitted to the veterinary toxicology laboratory.

Epidemic of self-poisoning with seeds of the yellow oleander tree (Thevetia peruviana) in northern Sri Lanka

Deliberate self-harm is an important problem in the developing world. Ingestion of yellow oleander seeds (Thevetia peruviana) has recently become a popular method of self-harm in northern Sri Lanka -- there are now thousands of cases each year. These seeds contain cardiac glycosides that cause vomiting, dizziness, and cardiac dysrhythmias such as conduction block affecting the sinus and AV nodes. This paper reports a study of the condition's mortality and morbidity conducted in 1995 in Anuradhapura General Hospital, a secondary referral centre serving 750 000 people in Sri Lanka's north central province. 415 cases were admitted to the hospital during 11 months; 61% were women and 46% were less than 21 years old. A prospective study of 79 patients showed that 6% died soon after admission. 43% presented with marked cardiac dysrhythmias which necessitated ther transfer to the coronary care unit in Colombo for prophylactic temporary cardiac pacing. The reasons for the acts of self-harm were often relatively trivial, particularly in children; most denied that they wished to die. Unfortunately, the case fatality rate for oleander poisoning in Sri Lanka is at least 10%. This epidemic is not only causing many unnecessary deaths, it is also putting immense stress on the already stretched Sri Lankan health services. There is an urgent need for an intervention which could be used in rural hospitals, thus preventing the hazardous and expensive emergency transfer of patients to the capital.

The toxicology of African herbal remedies

Toxicity related to traditional medicines is becoming more widely recognized as these remedies become popular in developed countries. Accidental herbal toxicity occurs not only as a result of a lack of pharmaceutic quality control in harvesting and preparation but also because herbal remedies are believed to be harmless. Although there is a huge amount of data available documenting the pharmacologically active ingredients of many plants, it is seldom helpful to the toxicologist in an acute situation. Current analytic methods such as high-performance liquid chromatography, gas chromatography--mass spectrometry, and immunoassays can provide identification of the toxin in those few cases in which the history or symptoms give a clear lead, but broad screening methods remain to be developed. In most cases of plant poisoning, treatment continues to be only of symptoms, with few specific antidotes available. It is important that toxicologists in the West be alert to the possibility of encountering poisoning in patients due to traditional African remedies.

Life-threatening plant poisoning

Each year over 100,000 exposures to toxic plants are reported to poison control centers around the country. This article focuses on the more toxic plant exposures which may result in critical care admissions. The various plants are identified and described. Their mechanism of toxicity, clinical presentation of exposure and a management strategy for the critical care physician are discussed. Resources for further information are also listed.