Eucalyptus oil poisoning

Essential oil related seizures (EORS): A multi-center prospective study on essential oils and seizures in adults

OBJECTIVE

Essential oils (EOs) like eucalyptus and camphor have pro-convulsant properties. These EOs are present in many over- the- counter balms and oils. The effect of exposure to these EOs and occurrence of seizure is not systematically studied. The aim of this study was to evaluate the relationship between essential oils and the first episode of seizure and breakthrough seizures in known epileptic patients.

METHODS

This was a multi-center prospective study, conducted in four hospitals over four years. Every person presenting with the first episode of seizure or breakthrough seizure was asked about exposure to EOs, mode of exposure, time to onset of a seizure in relationship to exposure, duration of seizure, type of seizure, and antiepileptic drug therapy.

RESULTS

During the four-year period there were 55 patients with essential oil-related seizure (EORS). 22(40 %) had essential oil-induced seizures (EOIS) and 33(60 %) had essential oil-provoked seizures (EOPS). The female: male ratio was 1:1.1, the age of the patients ranged from 8 months to 77 years. In the EOIS group, 95 % had generalized tonic-clonic seizures and 5% had focal impaired awareness seizures. In the EOPS group, 42.4 % had focal impaired awareness seizures, 27.3 % generalized tonic-clonic seizures, 15 % focal to bilateral tonic-clonic seizures, and 15 % focal aware motor seizures. EOs implicated were preparations containing eucalyptus and camphor.

CONCLUSION

Exposure to essential oils of eucalyptus and camphor is an under-recognized cause of the first and breakthrough seizure. Identifying the true causative factor will prevent unnecessary antiepileptic drug therapy and future recurrence.

Use of medicinal plants for headache, and their potential implication in medication-overuse headache: Evidence from a population-based study in Nepal

Background

In Nepal, traditional treatment using medicinal plants is popular. Whereas medication-overuse headache is, by definition, caused by excessive use of acute headache medication, we hypothesized that medicinal plants, being pharmacologically active, were as likely a cause.

Methods

We used data from a cross-sectional, nationwide population-based study, which enquired into headache and use of medicinal plants and allopathic medications. We searched the literature for pharmacodynamic actions of the medicinal plants.

Results

Of 2100 participants, 1794 (85.4%) reported headache in the preceding year; 161 (7.7%) reported headache on ≥15 days/month, of whom 28 (17.4%) had used medicinal plants and 117 (72.7%) allopathic medication(s). Of 46 with probable medication-overuse headache, 87.0% (40/46) were using allopathic medication(s) and 13.0% (6/46) medicinal plants, a ratio of 6.7:1, higher than the overall ratio among those with headache of 4.9:1 (912/185). Of 60 plant species identified, 49 were pharmacodynamically active on the central nervous system, with various effects of likely relevance in medication-overuse headache causation.

Conclusions

MPs are potentially a cause of medication-overuse headache, and not to be seen as innocent in this regard. Numbers presumptively affected in Nepal are low but not negligible. This pioneering project provides a starting point for further research to provide needed guidance on use of medicinal plants for headache.

Eucalyptus Oil-Induced Seizures in Children: Case Reports and Review of the Literature

Objective  Eucalyptus oil (EO)-induced seizures (EOIS) in children is a less recognized entity and a rare cause of acute symptomatic seizures. The purpose of this review outlines the clinical features and outcomes of EOIS with observed cases. Patients and Methods  We identified three pediatric patients with EOIS who were treated at Prathima Institute of Medical Sciences, Karim Nagar, India. Results  Seizures were developed in three children within 15 to 25 minutes after the ingestion of EO. All the children have taken EO first time and all have the first episode of seizures. One child had status epilepticus. Neuroimaging and electroencephalogram were normal. Two children were treated with antiepileptic drugs for 2 weeks. All the children were recovered within 2 days and none of them had a recurrence of seizures. Conclusion  EOIS is an underrecognized and rare entity. The knowledge or awareness of EOIS among health care professionals can prevent unnecessary investigations and long-term antiepileptic drug therapy.

A Pediatric Case of Accidental Eucalyptus Oil Poisoning from New Delhi, India: Emergency Measures, Historical Context, and Implications for Practice

Eucalyptus oil (EO) and EO containing products are readily available worldwide over the counter as topical nasal decongestants, rubefacients, anti-pyretics, and anti-inflammatory agents. However, EO is poisonous when orally ingested, or otherwise internally administered, resulting in serious outcomes such as seizures, vomiting, drowsiness, and even death. In this case report, we describe emergency measures adopted in a suspected case of EO ingestion by a 17-month-old female infant. It was found that stomach washes with normal saline followed by the oral administration of ranitidine to prevent vomiting restored and maintained normalcy over a 24-hour period. We situate our experience within the Indian context and recommend that pediatricians and healthcare workers routinely and explicitly warn parents about the serious consequences of the incorrect usage of substances containing essential oils in general and EO in particular.

Plant toxins and acute medicinal plant poisoning in children: A systematic literature review

BACKGROUND

For many years, medicinal plants and herbal therapy have been widely used in different societies for the treatment of various diseases. Besides their therapeutic potency, some of the medicinal plants have strong toxicity in human, especially in children and elderly. Despite common beliefs that natural products are safe, there have been few reports on their toxicities.

MATERIALS AND METHODS

In the present study, we aimed to systematically review the literature wherein acute plant poisoning and herbal intoxication have been reported in pediatric patients. After literature search and selection of the appropriate documents, the desired data were extracted and described qualitatively.

RESULTS

A total of 127 articles with overall 1453 intoxicated cases were collected. The results of this study showed that some medicinal plants can cause acute poisoning and complications such as hepatic and renal failure in children.

CONCLUSION

The findings of this survey showed that acute plant poisoning can be life?threatening in children, and since a single?ingested dose of toxic plants can cause acute poisoning, parents should be aware of these toxic effects and compare the side effects of self?medication with its potential benefits.

Antifungal activity of essential oils against fungi isolated from air

Fungal contamination of indoor air is an issue of increasing public health concern. Essential oils have been demonstrated to have antifungal capabilities, but there are limited studies investigating the efficacy of essential oils against fungi relevant to air quality. This study provides a preliminary screening of the antifungal properties of clove, lavender and eucalyptus essential oils against a range of fungal species isolated from environmental air samples. The ability of the essential oils to inhibit fungal growth was examined using the disk diffusion assay on malt extract agar and was compared with vinegar, bleach and limonene, with phenol as a positive control. Results identified essential oils which demonstrated antifungal potential against species of environmental origin. Clove oil was found to be most efficacious, with eucalyptus and lavender oils showing some antifungal potential albeit less broad spectrum and with less persistence over time in this assay. All essentials oils performed better than traditional cleaning compounds such as vinegar. Clove oil would be a suitable candidate for further research to validate its use in improving indoor air quality. Further research should next take into consideration the practical application method, concentration and long-term persistence of antifungal properties.

Beneficial and Healthy Properties of Eucalyptus Plants: A Great Potential Use

Eucalyptus (Eucapyptusspp.), an evergreen tall tree native to Australia and Tasmania, has been used since ancient times by the aboriginal population for several purposes. In particular, the speciesE. globulusis widely used in the pulp industry, as well as for the production of eucalyptus oil extracted on a commercial scale in many countries as raw materials in perfumery, cosmetics, food, beverages, aromatherapy and phytotherapy. The 1,8-cineole (eucalyptol), the principal and the most important constituent extracted from eucalyptus leaves, demonstrated an antimicrobial and anti-inflammatory activities. Despite the fact that the healthy effects of eucalyptus have been well established by research, further studies are necessary to investigate other prime effects of the plant and its possible implication in the treatment of a greater number of pathological conditions.

Oxidative stress response in canine in vitro liver, kidney and intestinal models with seven potential dietary ingredients

In vitro cell culture systems are a useful tool to rapidly assess the potential safety or toxicity of chemical constituents of food. Here, we investigated oxidative stress and organ-specific antioxidant responses by 7 potential dietary ingredients using canine in vitro culture of hepatocytes, proximal tubule cells (CPTC), bone marrow-derived mesenchymal stem cells (BMSC) and enterocyte-like cells (ELC). Cellular production of free radical species by denatonium benzoate (DB), epigallocatechin gallate (EPI), eucalyptol (EUC), green tea catechin extract (GTE) and sodium copper chlorophyllin (SCC), tetrahydroisohumulone (TRA) as well as xylitol (XYL) were continuously measured for reactive oxygen/nitrogen species (ROS/RNS) and superoxide (SO) for up to 24h. DB and TRA showed strong prooxidant activities in hepatocytes and to a lesser degree in ELC. DB was a weak prooxidant in BMSC. In contrast DB and TRA were antioxidants in CPTC. EPI was prooxidant in hepatocytes and BMSC but showed prooxidant and antioxidant activity in CPTC. SCC in hepatocytes (12.5mg/mL) and CPTC (0.78mg/mL) showed strong prooxidant and antioxidant activity in a concentration-dependent manner. GTE was effective antioxidant only in ELC. EUC and XYL did not induce ROS/RNS in all 4 cell types. SO production by EPI and TRA increased in hepatocytes but decreased by SCC in hepatocytes and ELC. These results suggest that organ-specific responses to oxidative stress by these potential prooxidant compounds may implicate a mechanism of their toxicities.

A systematic review of the reporting of adverse events associated with medical herb use among children

PURPOSE

Information about the safety of herbal medicine often comes from case reports published in the medical literature, thus necessitating good quality reporting of these adverse events. The purpose of this study was to perform a systematic review of the comprehensiveness of reporting of published case reports of adverse events associated with herb use in the pediatric population.

METHODS

Electronic literature search included 7 databases and a manual search of retrieved articles from inception through 2010. We included published case reports and case series that reported an adverse event associated with exposure to an herbal product by children under the age of 18 years old. We used descriptive statistics. Based on the International Society of Epidemiology's "Guidelines for Submitting Adverse Events Reports for Publication," we developed and assigned a guideline adherence score (0-17) to each case report.

RESULTS

Ninety-six unique journal papers were identified and represented 128 cases. Of the 128 cases, 37% occurred in children under 2 years old, 38% between the ages of 2 and 8 years old, and 23% between the ages of 9 and 18 years old. Twenty-nine percent of cases were the result of an intentional ingestion while 36% were from an unintentional ingestion. Fifty-two percent of cases documented the Latin binomial of the herb ingredients; 41% documented plant part. Thirty-two percent of the cases reported laboratory testing of the herb, 20% documented the manufacturer of the product, and 22% percent included an assessment of the potential concomitant therapies that could have been influential in the adverse events. Mean guideline adherence score was 12.5 (range 6-17).

CONCLUSIONS

There is considerable need for improvement in reporting adverse events in children following herb use. Without better quality reporting, adverse event reports cannot be interpreted reliably and do not contribute in a meaningful way to guiding recommendations for medicinal herb use.

Unintentional exposure of young children to camphor and eucalyptus oils

BACKGROUND

Essential oils, such as camphorated and eucalyptus oils, are volatile oils that can be absorbed by mouth and through the skin; if ingested orally by children, they can be harmful, even life-threatening.

OBJECTIVE

To determine the frequency of essential oil ingestion among children in Toronto, Ontario.

METHODS

Charts from December 1995 through March 1997 at the Ontario Regional Poison Information Centre, The Hospital for Sick Children, Toronto were reviewed to collect information on calls about essential oil ingestion, and a search of MEDLINE articles from 1966 to 1998 was conducted using the key words: 'camphor', 'eucalyptus', 'paediatric', and 'poisoning'.

RESULTS

Callers to the Poison Information Centre reported that 251 children had ingested an essential oil or product: eucalyptus oil 50 children; camphorated oil 18 children; VapAir (Drug Trading, Canada) vaporizing liquid 93 children; and Vicks VaporRub (Procter & Gamble, Canada) 90 children. The most common symptoms were cough, vomiting and cough associated with vomiting. Two children had seizures but recovered. The MEDLINE search found 18 reports of paediatric ingestion of the oils or oil products. The main symptoms were vomiting, lethargy, coma and seizures. One child died.

CONCLUSION

Although widely used by health care consumers, essential oils and the products that contain them can be harmful when ingested by children. Further education for parents and other caregivers about the risks involved in exposure to these products is required.

Pharmacokinetics of 1,8-cineole, a dietary toxin, in the brushtail possum (Trichosurus vulpecula): Significance for feeding

1,8-Cineole (cineole) is a Eucalyptus leaf toxin that defends against predation by herbivores such as the brushtail possum (Trichosurus vulpecula). The aim of the current study was to characterize the pharmacokinetics of cineole in the possum to improve understanding about how possums can avoid cineole toxicity when eating a Eucalyptus diet. Nine male possums were trapped in the wild and acclimated to captivity; a subcutaneous port was then implanted for venous blood sampling. Cineole was administered intravenously (10 and 15 mg kg(-1)) via a lateral tail vein and orally (30, 100 and 300 mg kg(-1)) by gavage, and blood concentrations of cineole and its metabolites were determined by gas chromatography. Cineole had a large terminal volume of distribution (V(z) = 27 l kg(-1)) and a high clearance (43 ml min(-1) kg(-1)), equal to hepatic blood flow. The terminal half-life was approximately 7 h. Oral bioavailability was low (F = 0.05) after low doses, but increased tenfold with dose, probably due to saturable first-pass metabolism. These findings indicate that when possums feed on a cineole diet, they eat until the cineole consumed is sufficient to saturate pre-systemic metabolism, leading to a rapid rise in bioavailability and cineole blood levels, and a cessation of the feeding bout. This is the first report on the pharmacokinetics of a dietary toxin in a wild herbivore, and provides insights into the interactions between the blood concentration of a plant secondary metabolite and the browsing behaviour of a herbivore.

Cloning and expression of koala (Phascolarctos cinereus) liver cytochrome P450 CYP4A15

In the present study, the cloning, expression and characterization of hepatic cytochrome P450 (CYP) CYP4A from koala (Phascolarctos cinereus), an obligate eucalyptus feeder, is described. It has been previously reported that microsomal lauric acid hydroxylase activity (a CYP4A marker) and CYP content were higher in koala liver in comparison to that in human, rat or wallaby, species that do not ingest eucalyptus leaves as food [Ngo, S., Kong, S., Kirlich, A., Mckinnon, R.A., Stupans, I., 2000. Cytochrome P450 4A, peroxisomal enzymes and nicotinamide cofactors in koala liver. Comp. Biochem. Physiol., C 127, 327-334]. A 1544 bp koala liver CYP4A cDNA, designated CYP4A15, was cloned by reverse transcription-polymerase chain reaction and rapid amplification of cDNA ends. The koala CYP4A15 cDNA encodes a protein of 500 amino acids and shares 69% nucleotide and 65% amino acid sequence identity to human CYP4A11. Transfection of the koala CYP4A15 cDNA into Cos-7 cells resulted in the expression of a protein with lauric acid hydroxylase activity. The koala CYP4A15 cDNA-expressed enzyme catalysed lauric acid hydroxylation at the rates of 0.45+/-0.18 nmol/min/mg protein and 4.79+/-1.91 nmol/min/nmol CYP (mean+/-SD, n=3), which were comparable to that of rat CYP4A subfamilies. Total CYP content for koala CYP4A15-expressed protein in Cos-7 cells was 0.094+/-0.001 nmol/mg protein (mean+/-SD, n=3) with negligible CYP content in untransfected Cos-7 cells lysate. Immunoblot analysis, using a sheep anti-rat CYP4A polyclonal antibody, detected multiple CYP4A immunoreactive bands in the liver from all species studied. The koala bands were found to be fainter and less confined but appeared much broader as compared to rat, human and wallaby. Northern blot analysis, utilising the koala CYP4A15 cDNA 417 bp probe, detected a mRNA species of approximately 2.6 kb in the koala liver and a mRNA species of approximately 2.4 kb in other species studied. Relative to the intensity of the beta-actin mRNA species, much stronger CYP4A mRNA signal was detected for koala liver relative to rat and human. In Southern blot analysis of EcoR 1-digested genomic DNAs, using the same koala CYP4A15 cDNA probe, the size of CYP4A gene fragments observed for the koala and other species were different, suggested a different CYP4A gene organization across species. Collectively, this study provides primary molecular data regarding koala CYP4A15 gene. The possibility that there may be higher CYP4A15 expression in the koala liver could not be excluded.

Feeding Behavior of Lambs in Relation to Kinetics of 1,8-cineole Dosed Intravenously or into the Rumen

The monoterpene 1,8-cineole is a major constituent of the essential oils that adversely influence intake of sage brush by herbivores, but little is known about the mechanisms of its action. We investigated the influence of 1,8-cineole on the feeding behavior of two groups of sheep, one group dosed intravenously and the other intra-ruminally. In the first study, we infused 40 mg/kg BW of 1,8-cineole intravenously into four lambs on wk 1, 2, and 4. In the second, we administered 125 mg/kg BW of 1,8-cineole into the rumen of four lambs as a single-bolus dose in wk 1 and 2. Lambs dosed intravenously spent less time feeding than controls (28 vs. 60 min; P<0.05), as did lambs dosed intra-ruminally (35 vs. 60 min; P<0.05). Dosed lambs ate less than controls during rumen dosing studies (P<0.05). For the intravenous infusion studies, rates of elimination did not differ among weeks (P<0.05). For the rumen infusion studies, however, the absorption rate constant increased from 0.035/min to 0.076/min from wk 1 to 2, while the absorption half-life declined from 24 to 10 min (P<0.05). Maximum plasma concentrations and time to reach maximum plasma concentrations were no faster in wk 2 than wk 1, but the primary elimination rate constant was 2.3 times higher in wk 2 (0.058/min) than in wk 1 (0.025/min) (P<0.05). Dosed lambs exhibited clinical effects-licking of lips, drowsiness, staggering, and 1,8-cineole-smelling breath-that were much more pronounced with intravenous than rumen infusions. Dosing did not affect the acid-base balance. Collectively, these data suggest 1) rapid absorption and distribution of 1,8-cineole was responsible for initiating satiety, while more prolonged excretion was responsible for the duration of the satiety effect, and 2) lambs more readily adapted to 1,8-cineole in the rumen-dose study than in the intravenous-dose study.

Rapid Absorption of Dietary 1,8-Cineole Results in Critical Blood Concentration of Cineole and Immediate Cessation of Eating in the Common Brushtail Possum (Trichosurus vulpecula)

The blood concentration of 1,8-cineole and its metabolites was measured in six male brushtail possums while they voluntarily fed on diets laced with varying concentrations of cineole for 3 d. On the third day, blood samples were collected during and after each bout of feeding for 3 hr. Blood cineole was measured by using headspace solid-phase microextraction (SPME), while cineole metabolites were measured by liquid-liquid extraction followed by gas chromatography-mass spectroscopy. Feeding patterns were measured by continual recording of residual food weight and time. Cineole absorption was rapid, resulting in a peak blood concentration at the end of each feeding bout. The blood concentration of cineole did not exceed a critical value (51.8 +/- 14.1 micromol/l) regardless of the concentration in the diet. Food and, therefore, cineole intake was regulated. The amount of food ingested in the first feeding bout decreased from 236 +/- 52 g on the control diet to 36 +/- 20 g on the 4% cineole diet. The amount of cineole ingested in the first bout (1.18 +/- 1.10 g) was the same regardless of the dietary concentration and was controlled by the size of the meal. Total food eaten during the 7-hr feeding session decreased by 64% from 368 +/- 94 g (control diet) to 131 +/- 52 g (4% diet). Total cineole intake increased from 2.47 +/- 0.60 g (1% diet) to 5.05 +/- 2.41 g (4% diet). Cineole metabolites accumulated throughout the sampling period and were generally still rising at the end of blood sampling period. Blood levels of metabolites were at least 10-fold higher than cineole levels. The immediate control of feeding seems to be regulated by blood levels of cineole, whereas metabolites are likely to be more important in regulating the chronic ingestion of cineole.

Eucalyptol, an essential oil, reduces contractile activity in rat cardiac muscle

Eucalyptol is an essential oil that relaxes bronchial and vascular smooth muscle although its direct actions on isolated myocardium have not been reported. We investigated a putative negative inotropic effect of the oil on left ventricular papillary muscles from male Wistar rats weighing 250 to 300 g, as well as its effects on isometric force, rate of force development, time parameters, post-rest potentiation, positive inotropic interventions produced by Ca2+ and isoproterenol, and on tetanic tension. The effects of 0.3 mM eucalyptol on myosin ATPase activity were also investigated. Eucalyptol (0.003 to 0.3 mM) reduced isometric tension, the rate of force development and time parameters. The oil reduced the force developed by steady-state contractions (50% at 0.3 mM) but did not alter sarcoplasmic reticulum function or post-rest contractions and produced a progressive increase in relative potentiation. Increased extracellular Ca2+ concentration (0.62 to 5 mM) and isoproterenol (20 nM) administration counteracted the negative inotropic effects of the oil. The activity of the contractile machinery evaluated by tetanic force development was reduced by 30 to 50% but myosin ATPase activity was not affected by eucalyptol (0.3 mM), supporting the idea of a reduction of sarcolemmal Ca2+ influx. The present results suggest that eucalyptol depresses force development, probably acting as a calcium channel blocker.

The effects of Eucalyptus terpenes on hepatic cytochrome P450 CYP4A, peroxisomal Acyl CoA oxidase (AOX) and peroxisome proliferator activated receptor alpha (PPARalpha) in the common brush tail possum (Trichosurus vulpecula)

Eucalyptus leaves contain a high proportion of essential oils comprising of a complex mixture of monoterpenes such as 1,8-cineole, alpha-pinene, d-limonene and p-cymene. In this study, hepatic levels of microsomal lauric acid hydroxylase and peroxisomal cyanide-intensive palmitoyl coenzyme A oxidative activities were examined in livers of possums given an artificial diet consisting of the above monoterpenes for 10 days. These values were compared with those of possums fed a control diet containing only fruits and cereals. Peroxisomal cyanide-intensive palmitoyl coenzyme A oxidative activity was significantly higher in livers of treated possums relative to that of control possums (2.96+/-0.93 vs. 0.98+/-0.88 nmol/mg protein per min, P<0.01) (mean+/-S.D., n=4). A small increase in microsomal lauric acid hydroxylase activity was observed in the treated possum in comparison with the control group (4.40+/-0.85 vs. 3.60+/-0.48 nmol/mg protein per min) (mean+/-S.D., n=4). A higher NAD/ NADP ratio was observed in treated possums as compared with control possums (4.73+/-0.65 vs. 3.51+/-0.64 nmol/mg protein per min, P<0.05) (mean+/-S.D., n=4). No other statistically significant differences in pyridine nucleotide contents were found between control and treated possums. Northern blot analysis of mRNA from rat, human, terpene treated and control possum livers, using the corresponding koala cDNA probes, detected a more intense acyl CoA oxidase (AOX) mRNA band in livers of terpene fed possums. Negligible differences in the intensity of CYP4A and PPARalpha mRNA bands were observed between the two groups. These data suggest that Eucalyptus terpenes elevate hepatic AOX expression in possums.

Side-effects of complementary and alternative medicine

Complementary and alternative medicine are increasingly used to diagnose or treat allergic diseases, and numerous studies have reported benefits of this type of medicine. This article presents a review of the literature on risks of these methods. The potential sensitizing capacity of numerous herbal remedies may lead to allergic contact dermatitis and more rarely to IgE-mediated clinical symptoms. Mechanical injuries may be observed following acupuncture leading to pneumothorax, cardiac tamponade or spinal injury. Infectious complications after acupuncture include hepatitis and bacterial endocariditis. Organ toxicity has been observed associated with various herbal preparations involving the liver, kidneys, and the heart. Some herbs may have cancerogenic properties. Severe nutritional deficiencies can occur in infants and small children given strict alternative diets, resembling 'kwashiorkor'. Finally, among other miscellaneous adverse effects, adulteration with steroids, and herbal and drug interactions are discussed. The pattern of side-effects is similar to that observed by the use of conventional medicine. Therefore, caution may be justified using both conventional and unconventional methods. Only if the benefit is proven and the side-effects are established, should a given method be chosen.

Constituents of aromatic plants: eucalyptol

The subacute toxicity studies reported up to now in rats and mice suggested that mice were less susceptible than rats to the toxicity of eucalyptol. In fact, after gavage, it was found toxic in male rats at doses higher than 600 mg/kg while no effect was seen in mice up to 1200 mg/kg. However, the limitations and the quality of the study do not allow the extrapolation of a 'no effect level'. Several reports in rat and brushtail possum show the formation of hydroxylated bicycled products of eucalyptol as main metabolites. Moreover, metabolites which require ring opening have been also detected. Following the accidental exposure of human beings, death was reported in two cases after ingestion of 3.5-5 ml of essential eucalyptus oil, but a number of recoveries have also been described for much higher amounts of oil.

Xenobiotic metabolism in Australian marsupials

The Australian marsupials are significant and unique Australian fauna. Xenobiotic metabolism is the process of enzymatic modification of xenobiotics, which include the chemicals, such as agricultural chemicals and natural dietary toxins, that these animals may be exposed to. Very little is known about the enzymes involved in xenobiotic metabolism in this unique group of animals. Folivore marsupials such as the koala (Phascolarctos cinereus and the brushtail possum (Trichosurus vulpecula) represent unique adaptation which has only been relatively superficially examined to date. We provide an overview of our current knowledge of marsupial xenobiotic metabolism.

Characterisation of tolbutamide hydroxylase activity in the common brushtail possum, (Trichosurus vulpecula) and koala (Phascolarctos cinereus): inhibition by the eucalyptus terpene 1,8-cineole

Plant constituents such as terpenes are major constituents of the essential oil in Eucalyptus sp. 1,8-Cineole and p-cymene (Terpenes present in high amounts in Eucalyptus leaves) are potential substrates for the CYP family of enzymes. We have investigated tolbutamide hydroxylase as a probe substrate reaction in both koala and terpene pretreated and control brushtail possum liver microsomes and examined inhibition of this reaction by Eucalyptus terpenes. The specific activity determined for tolbutamide hydroxylase in the terpene treated brushtails was significantly higher than that for the control animals (1865+/-334 nmol/mg microsomal protein per min versus 895+/-27 nmol/mg microsomal protein per min). The activity determined in koala microsomes was 8159+/-370 nmol/mg microsomal protein per min. Vmax values and Km values for the terpene treated possum, control, possum and koala were 1932-2225 nmol/mg microsomal protein per min and 0.80 0.81 mM; 1406-1484 nmol/mg microsomal protein per min and 0.87-0.92 mM and 5895-6403 nmol/mg microsomal protein per min and 0.067-0.071 mM, respectively. Terpenes were examined as potential inhibitors of tolbutamide hydroxylase activity. 1,8-Cineole was found to be a competitive inhibitor for the enzyme responsible for tolbutamide hydroxylation (Ki 15 microM) in the possum. In koala liver microsomes stimulation of tolbutamide hydroxylase activity was observed when concentrations of cineole were increased. Therefore, although inhibition was observed, the type of inhibition could not be determined.

Topical eucalyptus oil poisoning

Eucalyptus oil is well documented as being extremely toxic if ingested. We report a case of systemic eucalyptus oil toxicity from topical application. A 6-year-old girl presented with slurred speech, ataxia and muscle weakness progressing to unconsciousness following the widespread application of a home remedy for urticaria containing eucalyptus oil. Six hours following removal of the topical preparation her symptoms had resolved, with no long term sequelae.

Clinical effects and management of eucalyptus oil ingestion in infants and young children

OBJECTIVE

To determine the symptoms and signs of eucalyptus oil poisoning in infants and young children, to estimate the toxic dose and to recommend management strategies.

DESIGN AND SETTING

Retrospective analysis of case histories of children admitted to the Royal Children's Hospital, Melbourne, between 1 January 1981 and 31 December 1992 with a diagnosis of eucalyptus oil poisoning.

MAIN OUTCOME MEASURES

Demographic data, circumstances of ingestion, doses, clinical effects, management, complications and duration of hospital stay.

RESULTS

109 children (mean age, 23.5 months; range, 0.5-107) were admitted; clinical effects were observed in 59%. Thirty-one (28%) had depression of conscious state; 27 were drowsy, three were unconscious after ingesting known or estimated volumes of between 5 mL and 10 mL, and one was unconscious with hypoventilation after ingesting an estimated 75 mL. Vomiting occurred in 37%, ataxia in 15% and pulmonary disease in 11%. No treatment was given for 12%. Ipecac or oral activated charcoal was given for 21%, nasogastric charcoal for 57%, and gastric lavage without anaesthesia for 4% and under anaesthesia for 6%. All patients recovered. Hazardous treatment and overtreatment were common. For 105 children, mean hospital stay was 22 hours (range, 4-72 h) and for 13 patients mean intensive care unit stay was 18 hours (range, 4-29 h). In 27 patients who ingested known doses of eucalyptus oil, 10 had nil effects after a mean of 1.7 mL, 11 had minor poisoning after a mean of 2.0 mL, five had moderate poisoning after a mean of 2.5 mL and one had major poisoning after 7.5 mL (P = 0.0198).

CONCLUSIONS

Ingestion of eucalyptus oil caused significant morbidity in infants and young children. Significant depression of conscious state should be anticipated after ingestion of 5 mL or more of 100% oil. Minor depression of consciousness may occur after 2-3 mL. Airway protection should precede gastric lavage.

Eucalyptus oil poisoning in childhood: 41 cases in south-east Queensland

Forty-two cases of oral eucalyptus oil poisoning in children under 14 years of age were identified in a defined population between 1 July 1984 and 30 June 1991, and 41 were subjected to retrospective case note analysis. Thirty-three children (80%) were entirely asymptomatic. This group included all of the four children reported to have ingested more than 30 mL of eucalyptus oil. Only two of the remaining children had symptoms or clinical signs on presentation to hospital. No child required advanced life-support. There was no correlation between the amount of eucalyptus oil taken and the presence of symptoms. If the estimated volume ingested is large, or symptoms are evident, on presentation at hospital gastrointestinal decontamination should lead to a good outcome with few clinical problems. Eucalyptus oil may be a less toxic compound than has previously been believed.

A comparison of apical seal: chloroform versus eucalyptol-dipped gutta-percha obturation

Three groups of extracted teeth were obturated using gutta-percha and lateral condensation. In one group the gutta-percha was dipped in chloroform before condensation. In a second a eucalyptol dip was used. No dip was used in the third group. A dye penetration study was done to compare leakage among the three groups. The teeth were cleared for viewing and measurements of dye penetration were made using a stereomicroscope. Statistical analysis using Kruskal-Wallis one-way analysis of variance of the results showed no significant difference among test groups at the 0.05 level.