Aetheroleum Eucalypti is the essential oil obtained by steam distillation and rectification of the fresh leaves or terminal branchlets of Eucalyptus globulus Labill (Myrtaceae) or other Eucalyptus species rich in 1,8-cineole (1-3).
Eucalyptus cordata Miq., E. diversifolia Miq., E. gigantea Dehnh., E. glauca D.C., E. globulus St Lag., E. pulverulenta Link (4).
Selected vernacular names
Aceite de eucalipto, esencia de eucalipto, essence d’eucalyptus rectifiée, eucalipto essenza, eucalyptus oil, eucalyptus olie, Eucalyptusöl, huile essentielle d’eucalyptus, klei de eucalipt, minyak ekaliptus, oleo de eucalipto, Oleum eucalypti, tinh dâu Bach dan (1-7).
Indigenous to Australia, cultivated in subtropical regions of the world including Africa, South America (e.g. Argentina, Brazil and Paraguay), Asia (e.g. China, India and Indonesia), southern Europe and the United States of America (4, 7-11).
A large tree with smooth bark, very pale or ash-grey, up to 3-20 m high. Branchlets quadrangular, glaucous. Leaves of young trees and first leaves of young shoots opposite, sessile, oval-oblong, with a cordate base, farinaceousglaucous; older leaves dangling, spirally arranged, lanceolate-falcate, up to 30 cm long. Flowers with very short pedicels, mostly umbellate, sometimes 2-3 in a fascicle. Calyx-tube double: outer tube drops early, smooth, inner tube semi-persistent and warty. Stamens about 1.5 cm long; fruit turbinate, angular, 2.0-2.5 cm in diameter (12, 13).
Plant material of interest: essential oil
A colourless or pale yellow liquid that darkens slightly on long storage (1, 2).
Odour: aromatic, camphoric; taste: pungent, camphoric, followed by a sensation of cold (1-3).
Powdered plant material
General identity tests
Thin-layer and gas chromatography (1-3).
Tests for specific microorganisms and microbial contamination limits are as described in the WHO guidelines on quality control methods for medicinal plants (14).
Refractive index: 1.458-1.470 (1-3); specific gravity: 0.906-0.925 (2); optical rotation: 0° to +10° (2); solubility in ethanol: soluble in 5 volumes of 70% ethanol (2, 5). Methods to detect the presence of aldehyde and phellendrene are available (2).
The recommended maximum limit of aldrin and dieldrin is not more than 0.05mg/kg (15). For other pesticides, see the European pharmacopoeia (15), and the WHO guidelines on quality control methods for medicinal plants (14) and pesticide residues (16).
For maximum limits and analysis of heavy metals, consult the WHO guidelines on quality control methods for medicinal plants (14).
Where applicable, consult the WHO guidelines on quality control methods for medicinal plants (14) for the analysis of radioactive isotopes.
Contains not less than 70% (w/w) 1,8-cineole (also known as cineol, cineole or eucalyptol) (1, 2). Quantitative analysis according to the method described for 1,8-cineole (1-3).
Major chemical constituents
The major constituent is 1,8-cineole (54-95%). In addition, there are moderate amounts of α-pinene (2.6%), p-cymene (2.7%), aromadendrene, cuminaldehyde, globulol and pinocarveol (11, 13). The structure of 1,8-cineole is presented below.
Uses supported by clinical data
Uses described in pharmacopoeias and in traditional systems of medicine
Symptomatic treatment of catarrh and coughs (17, 18). As a component of certain dental root canal sealers; topically as a rubefacient for treatment of rheumatic complaints (18, 19).
Uses described in folk medicine, not supported by experimental or clinical data
Treatment of cystitis, diabetes, gastritis, kidney disease (unspecified), neuralgia, laryngitis, leukorrhoea, malaria, pimples, ringworm, sinusitis, wounds, ulcers of the skin, urethritis and vaginitis (4, 6).
Aetheroleum Eucalypti inhibited the growth in vitro of Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, Enterococcus faecalis and Escherichia coli (20-25), but not of Bacillus cereus, Penicillium cyclopium or Aspergillus aegyptiacus (22, 25). Intramuscular injection of the essential oil (500mg/kg body weight) inhibited the growth of Mycobacterium tuberculosis in guinea-pigs, and enhanced the efficacy of streptomycin and isoniazid (26).
The essential oil inhibited prostaglandin biosynthesis in vitro at a concentration of 37µmol/l (27).
Respiratory tract effects
Intragastric administration of the essential oil increased respiratory tract secretions in cats (100mg/kg body weight), guinea-pigs (50mg/kg body weight), rabbits (100 mg/kg body weight) and rats (100mg/kg body weight) (28). Administration of non-lethal doses of the essential oil by steam inhalation to urethane-treated rabbits did not enhance the output of respiratory tract fluid (29).
The antitussive effect of the essential oil was compared to that of codeine in guinea-pigs in which coughs were induced by mechanical stimulation. Inhalation of the essential oil (5% emulsified in normal saline) had a significant antitussive effect relative to codeine (15mg/kg body weight) of 0.68 (P < 0.05). When the essential oil was administered by intraperitoneal injection (50mg/kg body weight), the antitussive effect relative to codeine was 0.57, which was also significant (P < 0.001) (30).
Nasal decongestant activity
A clinical trial without controls assessed the effects of Aetheroleum Eucalypti as a nasal decongestant in 31 healthy volunteers. Inhalation of the essential oil (10 ml) over a period of 5 minutes had no effect on nasal resistance to airflow. However, the oil had a stimulant or sensitizing effect on nasal cold receptors, and the majority of subjects reported a sensation of increased airflow (31). A single-blind, parallel clinical trial assessed the efficacy of vaporized essential oil, camphor, menthol or steam in reducing nasal congestion in 234 patients with acute respiratory tract infections. The essential oil was significantly more effective in reducing nasal congestion only during the first hour following treatment (P < 0.02) (32). In other clinical studies of patients with acute common colds, no significant differences in nasal decongestant activity were reported between the essential oil (1.3%) in petrolatum and a petrolatum placebo (32).
A randomized, double-blind, placebo-controlled, crossover study assessed the efficacy of a combination product of the essential oil (eucalyptus oil) and Aetheroleum Menthae Piperitae (peppermint oil) for headache relief in 32 patients. Five different preparations were used (all in 90% ethanol, to a final weight of 100g): 10g peppermint oil and 5g eucalyptus oil; 10 g peppermint oil and traces of eucalyptus oil; traces of peppermint oil and 5g eucalyptus oil; traces of both peppermint oil and eucalyptus oil; or a placebo. The test preparations or placebo were applied topically to large areas of the forehead and temples, and the effects on neurophysiological, psychological and experimental algesimetric parameters were measured. All test preparations improved cognitive performance, and induced muscle and mental relaxation compared to the placebo, but had no effect on sensitivity to headache (33).
Preparations of Aetheroleum Eucalypti should not be administered internally to children (34), or patients with inflammation of the gastrointestinal tract, gall bladder disease or impaired liver function (4, 17, 34). Aetheroleum Eucalypti should not be taken internally during pregnancy (35), see Precautions.
Aetheroleum Eucalypti preparations should not be applied to the face, especially the nose, of infants or young children (17). Keep out of reach of children.
Oily vehicles for the essential oil are unsuitable for use in nasal sprays as the vehicle inhibits ciliary movement and may cause lipid pneumonia (19).
Although no published drug interactions were found, a number of animal studies indicate possible concern that the essential oil may induce liver enzymes involved in drug metabolism. Therefore, the effects of other drugs may be decreased following concomitant administration (17, 36).
Carcinogenesis, mutagenesis, impairment of fertility
The essential oil was a weak promoter of papilloma formation by 9, 10- dimethyl-12-benzanthracene in mice. However, the development of tumours in mice after intragastric administration of 8 or 32 mg 1,8-cineole per kg body weight daily for 80 weeks was similar to that in mice treated with vehicle controls (37).
Pregnancy: teratogenic effects
The essential oil was not teratogenic when administered subcutaneously to pregnant mice (135 mg/kg body weight) daily on days 6-15 of gestation (38).
Pregnancy: non-teratogenic effects
Eucalyptol (500mg/kg body weight, administered subcutaneously) has been reported to penetrate the placenta in rodents and reach concentrations in the fetal blood which are sufficient to stimulate hepatic enzyme activity (39). Therefore, Aetheroleum Eucalypti should not be taken internally during pregnancy (35).
See Contraindications and Warnings.
No information available on precautions concerning drug and laboratory test interactions or nursing mothers. Therefore, Aetheroleum Eucalypti should not be administered during lactation without medical supervision.
Topical applications of Aetheroleum Eucalypti are generally non-irritating, nonsensitizing and non-phototoxic (40). However, one case of systemic toxicity in a 6-year-old girl (41), and several cases of urticaria, contact dermatitis and skin irritation (42) have been reported.
Between 1981 and 1992, the clinical effects of poisoning were observed in 59% of 109 children after accidental ingestion of the essential oil (2-10 ml) (43, 44). The symptoms included depression of conscious state (28% of cases), drowsiness (25% of cases) and unconsciousness (3% of cases), and were dosedependent (43). Other reported symptoms included epigastric burning, nausea, vomiting, dizziness, muscular weakness, miosis, a feeling of suffocation, cyanosis, delirium and convulsions (8, 18, 45). Allergic reactions have been reported after ingestion of 20 lozenges containing the essential oil (46).
Between 1889 and 1922, 17 cases of fatal poisoning due to ingestion of the essential oil were reported (36). A dose of as little as 3.5ml was fatal (47). However, these data are old and the purity of the oil used is unknown.
Essential oil in solid, semisolid or liquid preparations (1) and galenical preparations (17). Store in a well-filled, tightly closed container, protected from heat and light (1, 2).
(Unless otherwise indicated)
Daily dosage: 0.3-0.6 ml essential oil or equivalent preparations (17). Capsules: 1 capsule of 100-200 mg, 2-5 times daily (48, 49). Lozenges: 1 lozenge of 0.2-15.0 mg dissolved slowly in the mouth, every 30-60 minutes (32). Mouth-wash: 20 ml of a 0.91 mg/ml solution, gargled twice daily (32). Inhalation: 12 drops/150 ml boiling water (49).
Daily dosage: several drops (17) or 30 ml essential oil in 500ml lukewarm water (35) rubbed into the skin for local application; 5-20% essential oil in liquid and semisolid preparations; 5-10% in hydroalcoholic preparations.
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