CHAPTER 38
Medication and Diet
Medication: general principles
Parents often feel uneasy about using medication to alter their children’s
behaviour or emotions; teachers and mental health professionals may feel
the same. These concerns are understandable and partly justified. For
example, children and adolescents with an intellectual disability may be
given high doses of neuroleptics for long periods in a futile attempt to
suppress their challenging behaviour. But even though it is true that psy-
chotropic medication can be used unwisely, it is important to remember
that suitable doses of the right medication used for an appropriate indica-
tion can be of great benefit. The continuing use of terms such as ‘chemical
cosh’ or ‘chemical straitjacket’ by some journalists when describing the use
of evidence-based treatments is inaccurate and unhelpful.
Prescribing for children and adolescents is not simply a matter of
scaling adult doses down in proportion to body weight. Because of age-
related changes in pharmacokinetics and pharmacodynamics, paediatric
psychopharmacology is both quantitatively and qualitatively different
from adult psychopharmacology.
Pharmacokinetics
The relationship between the dose administered and the effective con-
centration in the brain depends on several pharmacokinetic factors (see
Box 38.1). Developmental considerations are relevant to each of these
factors – these will be described first for children. Compliance may depend
more on the motivation of parents and teachers than on that of the child.
Absorption can be influenced by the fact that stomach acidity is generally
lower in children. This reduces the rate of absorption of acidic drugs
such as tricyclics (since less of the drug is in the lipid-soluble un-ionised
form). Children have particularly active livers, so clearance is fast for drugs
metabolised by the liver. This results in an exaggeration of the normal
‘first pass’ effect, that is, a particularly high fraction of the medication
absorbed by the gut is cleared by the liver from the portal circulation
Child and Adolescent Psychiatry, Third Edition. Robert Goodman and Stephen Scott.
©c2012 Robert Goodman and Stephen Scott. Published 2012 by John Wiley & Sons, Ltd.
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