At the end of Aromatherapy Awareness Week, let’s have a look at essential oils safety on infants and young children from slightly different angles. Whilst the qualities of essential oils are important, the basic metabolic pathways cannot be neglected when talking about using essential oils safely, as with other natural medicine such as food (!) and/or conventional ones.
The need for a dosage rules for medicines for children existed from the 8th century; age-based Dilling’s rule (Bone & Mills, 2013; Lack & Stuart-Taylor, 1997). Weight-based rule came along in the 1930s by A.J. Clark of Endiburgh (Bone & Mills, 2013; Lack & Stuart-Taylor, 1997). Bartelink et al (2006) recommend it for 2-6 months of age. The British National Formulary and major text books recommend body surface area (BSA) to be used for calculation of drug dosages for children (Bone & Mills, 2013; Lack & Stuart-Taylor, 1997). It may be appropriate after 6-months of age according to Bartelink et al (2006). Paediatirc dosing is complex: pharmacokinetics, pharmacodynamics and dose requirements are not clearly understood, and more research is needed (Lu & Rosenbaum, 2014).
Why do we need different dosages for children? It’s because our little people are not quite the same as small version of adults. Their physiology and biochemistry are very different from us, adults and they are very vulnerable (Lu & Rosenbaum, 2014; WHO, 2010). Their bodies are growing especially during the first 2 years of life (Lu & Rosenbaum, 2014). Maturation of hepatic enzymes and physiological maturation of organ systems are some of the factors that differentiate infants and children from adults (Bryant & Knights, 2011). Now let’s have a look briefly at pharmacokinetics of infants & young children, keep in mind the use of essential oils by inhalation and topical application 😉
Infants and young children have the thin skin: stratum corneum that greatly enhance permeability and topical absorption (Lu & Rosenbaum, 2014: WHO, 2010). They have better hydration of the epidermis (Lu & Rosenbaum, 2014: WHO, 2010) and although there are exceptions, increased tissue hydration generally appears to increase transdermal delivery of both hydrophilic and lipophilic permeant (Williams & Barry, 2003). Larger surface area in proportion to body mass means they are facing more risks of systemic absorption from topical application (Bryant & Knights, 2011: Furue et al, 2003). The mucus barrier plays an important protection against foreign particles and chemicals entering the lung (Lillehoj & Chul Kim, 2002), however Neonates’ lungs lack much of it (Bryant & Knights, 2011).
Their total body water and fat composition are significantly different from those of adults. Total body water alters from approximately 80% of body weight at birth, down to 65% at 12 months, and 50-60% for adults (Bryant & Knights, 2011; Lu & Rosenbaum, 2014; WHO, 2010). Their total fat content is about 1-3% of body weight in premature infants, 10-15% in full-term neonates, 20-30% at 1 year old and about 18% in the average adult (Lu & Rosenbaum, 2014; WHO, 2010). Neonates and infants’ tend to have reduced protein binding, that may cause an increased distribution of medicine from the plasma to the rest of the body (Lu & Rosenbaum, 2014). WHO (2010) stated that the blood-brain barrier is functionally incomplete in the neonate and lipid-solubility of substance determines the rate of penetration into the brain.
Substances are metabolised in the liver, and its primary purpose is to make substances more water-soluble to enhance renal excretion (Lu & Rosenbaum, 2014). The liver of a 3-month-old has about one-third of the overall biotransformation capacity of those of adults (Cresteil, 2009). The delayed maturation of hepatic enzyme function in infants and young children means slower clearance and prolonged renal elimination, that may lead to increase toxicity of some medicine (Bryant & Knights, 2011; Cresteil, 2009). By the time the infant is 12 months, drug absorption, distribution and excretion are similar to that of an adult except hepatic metabolism, which is an age-dependent (Bryant & Knights, 2011). Children under 10 years have increased hepatic clearance as their liver is proportionally larger to body weight than in adult (Bryant & Knights, 2011; Cresteil, 2009; WHO, 2010).
Excretion of medicines by the kidney has 3 processes: glomerular filtration, tubular excretion and tubular reabsorption (Lu & Rosenbaum, 2014). Around 3 to 6 months of age, their glomerular filtration rate in the kidney reaches adult capacity but tubular function does not mature until around 12 months old (Bryant & Knights, 2011: Lu & Rosenbaum, 2014; WHO, 2010). Generally the lower the gestational age of infant, the longer the half-lives of medicine will be (Lu & Rosenbaum, 2014; WHO, 2010). The delay in the development of tubular functions may cause variable effect on medicine’s clearance (Lu & Rosenbaum, 2014). Apparently Paracelsus, the father of toxicology said “All things are poison and nothing is without poison. Soley the dose determines that a thing is not a poison” (Grandjean, 2016). Dosage needs to be matched to the maturity of the elimination process in children during the first year and it is best to avoid unnecessary exposure to drugs or chemicals (Cresteil, 2009).
When using essential oils on infants and young children, please take above points into considerations and know how to handle essential oils with due respect. 🙏 There is a good general guidelines for the essential dosage for different age groups by Tisserand Institute (please see the image) 😊 Please remember some essential oils are gentler on the mucus membranes and the skin. If you wish to use essential oils safely, please seek professional advice from your local qualified aromatherapists, who have been trained in clinical aromatherapy with a minimum qualification of Diploma of Aromatherapy (HLT51407) or equivalencies.
Image: StockSnap and Tisserand Institute http://tisserandinstitute.org/…/recommended-dilutions-for-…/