A brief insight into certain TDM pointers for Geriatric and Paediatric patients.

1. TDM Pointers –
Geriatric & Paediatric Patients

2. Geriatric Patients
 Aim of therapy: To prolong life and improve the QoL of
the patient.
 Elderly people often receive multiple drugs for their
multiple diseases.
 Polypharmacy increases the risk of drug interactions and
ADRs.
 CV agents, Diuretics, Analgesics, GI agents, Antidiabetics,
Potassium supplements are among the drug classes that
are very problematic in the geriatric populations.
 For certain conditions, it is better to advise non-drug
therapies of proven efficiency.

3.  Common hepato-renal issues in geriatric pts.:
• Reduced renal clearance;
• Limited reserves of renal function;
• Highly susceptible to nephrotoxic drugs;
• Excrete drugs slowly;
• Reduced hepatic metabolism of drugs;
 Unnecessary use of hypnotics should be avoided
(measures could include emptying the bladder before
going to bed to avoid having to get up in the middle of
the night, or avoiding stimulant drugs in the evening or
night).

4.  Decline in integrity of various organs and systems
involved in the ADME of drugs.
 On average, there is a 7x increase in drug toxicity as
age increases from 20 – 79 yrs.

5. Absorption:
• gastric acid secretion, gastric pH;
• GI motility
• active absorption of Vitamins, Fe, Ca.
Distribution:
• body fat from 15-30% (on average);
• lean body wt. proportionally to body weight;
• Vd of lipophilic drugs (diazepam, chlordiazepoxide, etc.);
• albumin conc. (Inc. unbound fraction of drugs like
phenytoin in the circulation);
• On average, total PP conc. is relatively constant

6. Metabolism:
 liver mass and liver blood flow;
 For drugs which undergo Phase-I metabolism
(oxidation and reduction), metabolism with increase in
age (e.g.,Lidocaine, propranolol, phenytoin,
theophylline, etc.).
 For drugs which undergo Phase-II metabolism, the
metabolism is relatively unaffected (Isoniazid by
acetylation; Temazepam by glucuronidation).

7. Excretion:
• nephron nos.;
• functioning glomeruli;
• renal blood flow;
• GFR,
• muscle mass leading to SCr
• Dose adjustments must definitely be made for
aminoglycosides, digoxin, methotrexate, quinidine,
tetracyclines.

8.  The margin between therapeutic effect and toxicity is
so small.
 E.g., Age-related toxicity of BZs with long half-lives has
made the use of these drugs undesirable in elderly
patients.
(Amitryptylline, Barbiturates, Reserpine, indomethacin,
Chlorpropamide).
 Always ensure that the optimal number of drugs are
prescribed for the patient.

9.  Complex drug regimen mostly results in non-
compliance due to age-related slowness of
comprehension, memory lapses, and loss of vision.
 For complex therapeutic regimen, it is better to use
different coloured medications (as much as
possible).
 It is better to avoid large tablets and capsules due
to difficulty in swallowing.
 As far as possible, aim for OD dosing than more
frequent dosing regimen.

10.  Elderly patients should be taught to ‘understand’ the drugs
they must take.
 Spend extra time to advise (in a more simplified manner)
the patients regarding the administration technique, dosing
schedule.
 Sometimes it may be necessary to provide clear
instructions in writing.
 Use of drug diary or calendar should be encouraged.
 For geriatric patients, it is also better to involve family
members / close friends / care home staff.
 Regular review of the medications administered to the
geriatric patients must be done.

11. Paediatric Patients

12. • Compared to the adult population, drug use has not been as
extensively researched.
• In many cases, drug treatment is not really required.
• The increased affinity (in general) towards naturopathy has
resulted in exacerbation of many disease conditions.
• Over-prescription of antibiotics is a huge concern.
• When dispensing a medication for an acute illness, the
pharmacist must explain the reason(s) for the medication
being given; dose and dosing frequency; precautions to be
taken to the parents.
• Drug selection should be based on relative risk and clinical
considerations.
• Focus should also be on the AEs of the medications in the
paediatric patients.
E.g., Sulphonamides (cotrimoxazole, among others) cause
kernicterus.

13. Medications
Sulphonamides (including
cotrimoxazole)
Kernicterus (bilirubin-induced brain dysfunction)
Tetracyclines Tooth staining and damage
Aspirin Reye’s syndrome (causes swelling in liver and
brain)
Ibuprofen Can cause serious toxicity in children with renal
diseases.
Potent topical corticosteroids Unsuitable for routine use in neonates and young
children due to significant systemic absorption,
adrenal suppression and growth retardation.
Lidocaine High potential for seizures
MMR Vaccine (gelatin or egg
proteins)
Anaphylaxis

14.  The choice of formulation is extremely important for this
population.
 Review various info.: ease of administration, routes
available, size of medication, taste, safety and the
excipients.
 Generally, the dosage is calculated based on the body
weight, BSA, developmental stage, and physiological
function.
 The rapidly changing body size, body weight, and
physiological function observed in children undergoing
treatment make it necessary to constantly review and adjust
drug dosages (if required).
 Rectal suppositories cannot be reliably absorbed unless they
are retained in the body. This is very difficult to assure in
case of paediatric cases.

15.  Paediatric issues with routes of administration:
 Slow infusion rates of medication
 Low muscle mass; Skin absorption capacity;
 Rapid GI transit; Lack of anal sphincter control
 Poor compliance w/ administration
 E.g., If a life-saving drug is administered into a slowly
running I.V. line running at 3ml/hr, it can take 6-8 hrs.
before a detectable conc. begins to appear in the plasma.
This can potentially lethal in many paediatric patients.
 Rapid GI transit time unreliable absorption of slowly
absorbed orally administered drugs
• E.g., SR preparations are formulated to release the drug
over 12 – 24 hrs. The dose cannot be delivered reliably if
the preparations are excreted from the body 2-4 hrs.
post-administration.

16.  Whenever possible, the oral route of admn. should be
preferred.
 Liquid preparations (oral route) are most suitable for
children < 5 yrs.
 Though liquid preparations are suitable, they contain sugar,
which can increase the risk of dental decay. For long-term
therapy, it is better to switch to sugar-free versions.
 Capsules can be emptied and ‘disguised’ in jam or honey.
 Parenteral routes are more appropriate in cases where the
patient presents with vomiting or significant diarrhoea.
 Rectal admn. has been proven to be useful in certain cases:
• Diazepam for convulsions;
• Glycerin for constipation;
• Paracetamol for fever w/ vomiting;
 Inhalers: Paediatric patients in most cases won’t be able to
properly use inhalers. It is better to use ‘nebulizers’ and/or
‘spacers’.

17.  Factors to consider when opting for the type of oral dosage
form:
 BA; Palatability; Convenience; Availability of various drug
forms; Cost; Stability; Toxicity;
 Dosage is based on body weight, body surface area.
 Medication errors can occur due to difficulty in accurately
measuring paediatric doses / use of incorrect / inaccurate
measuring devices.
 Household teaspoons can contain anywhere between 2.5-7.5
ml. They can be confused with tablespoon, especially when
abbreviations are used on the prescription.
 Use of oral syringes and/or cups can eliminate certain
administration errors. However, this is also problematic in
case of parents who cannot read properly or understand cup
markings.
 Pharmacists should countercheck if the medication should be
diluted for paediatric cases.

18.  Pharmacists must advise parents not to add any medicines
to the content of the infant’s feeding bottle, since the drug
may interact with milk or other liquid in it. The ingested
dosage may be reduced, if the child does not drink all the
contents.
 Parents should be warned to keep all medicines out of the
reach of children.

19. THE END