DRUG PRESCRIPTION IN ELDERLY SUBJECTS

Introduction :

• Due to the constant increase in drug consumption in the elderly population, drug prescription is becoming a public health problem.
• Polypathology justifies the prescription of multiple treatments, but polymedication is the main risk factor for iatrogenesis, the consequences of which are severe in elderly patients.
• Subjects at risk of iatrogenesis are patients who are malnourished, have renal failure, are demented or have a motor or sensory disability.
  1. General information on the characteristics of elderly people:

The elderly person has the following characteristics:

• Decreased kidney and liver function
• The concomitance of several pathologies and therefore often polymedication (notion of fragility)
• Modification of pharmacokinetics and pharmacodynamics of drugs.

1. Decreased kidney and liver function:

Liver and kidney function deteriorate with age, and this is especially true as people get older.

In the elderly, the rate of hepatic transformation of drugs is often reduced by reduction in liver mass and hepatic blood flow.

Thus, the glomerular blood flow is reduced, the decrease in glomerular filtration is 2 to 10% per decade which causes a decrease in the urinary excretion of certain drugs, such as for example: aminoglycosides, low molecular weight heparin, etc. These modifications require for certain drugs, the reduction of their usual dosage.

2. The concept of fragility (multiple pathologies and polymedication):

• The frail elderly person is a vulnerable elderly person, and it is estimated that half of the elderly population is considered frail.

These are people in social isolation, malnourished, with multiple pathologies and with multiple treatments.

• The pathologies that often affect elderly people are: HBP, diabetes, renal failure, heart failure, often these pathologies are concomitant which indicates polymedication.
• Adverse effects of medications prescribed by the dentist are more frequent when medication consumption is higher.
• For our elders, the drugs responsible for adverse effects in the elderly are Cardiovascular drugs, Central nervous system drugs, Hypoglycemic drugs, Analgesics and NSAIDs.

3. Changes in drug pharmacokinetics and pharmacodynamics:

• Changes in the body during aging will have consequences on the action of drugs and their administration:
• Pharmacokinetics: This is the study of how the body absorbs, distributes, metabolizes and excretes drugs. Frequent malnutrition in elderly subjects is responsible for hypoproteinemia and hemoconcentration resulting in an overdose of drugs bound to plasma proteins. Renal function, reduced with age, also increases the risk of drug overdose.
• Pharmacodynamics: This is the study of how drugs act on the body. For example: hypotensive drugs can more readily cause orthostatic hypotension with falls and fractures in an osteoporotic person.

2. General principles of drug prescription in the elderly in Odontostomatology:

To safely care for an elderly person, it is important to “consider them as a whole, that is to say:

1. Carry out a good interview and a good clinical examination (listen to the patient which constitutes a good psychological approach)
2. Know the patient’s general history, and all current pathologies as well as associated drug treatments
3. Contact the other treating physician(s).
4. Assess your weight, blood pressure and nutritional status
5. Choose, if the prescription is necessary, the medication:

• Having the least side effects and interactions;
• Having the widest margin of safety;
• Having the shortest half-life;
• Having the route of administration and the dosage form most suited to the patient’s disabilities.

3. DRUG-INDUCED IATROGENESIS IN ELDERLY SUBJECTS:
   • A disease, a condition, a side effect, are said to be iatrogenic when they are caused by medical treatment.
   • From the Greek iatros: doctor, génès: engendered
   • Drug-induced iatrogenesis constitutes a public health problem, particularly among elderly people.
4. DRUG INTERACTIONS:

Polymedication results in three types of interactions

Four therapeutic groups are mainly incriminated in the occurrence of adverse effects in the elderly:

• Cardiovascular drugs
• Psychotropic drugs.
• Painkillers and NSAIDs.
• Anti-infectives.

It should be noted that three of these four families are frequently prescribed by the dental surgeon.

5. Practical application of the prescription in the elderly:

On a practical level, among the drugs most used by the dentist:

1. Nonsteroidal anti-inflammatory drugs (NSAIDs):

These drugs are generally contraindicated in the elderly due to their nephrotoxicity.

In addition, there is a risk of poor digestive tolerance.

There is also a risk of cardiac decompensation in the event of underlying heart disease, which is very common in the elderly.

In terms of drug interactions, the combination of NSAIDs and AVK (anti-vitamin K) is contraindicated and there is an increased risk of bleeding in the case of combination with aspirin and other antiplatelet agents.

2. Antibiotics:

The dosage of most antibiotics should be adjusted according to renal function in the elderly, so it is important to know the creatinine clearance.

(A clearance of less than or equal to 90 ml/mm corresponds to normal renal function. If it is less than or equal to 60 ml/mm, we speak of moderate renal failure.

We will speak of terminal renal failure below a value of 15 ml/mm). We must also pay attention to interactions with oral anticoagulants and the risk of imbalance of this treatment. Close monitoring of the INR is then necessary.

3. Local anesthetics: The use of local anesthesia products only requires knowledge of a history of allergy or not to these products in the patient. There is no necessary adaptation, in terms of quantity, of product for our elders.
4. Painkillers (analgesics):

The prescription of level I analgesics (paracetamol) requires an adaptation of the dosage to the weight of the person, namely 60mg/kg/day or 15mg/kg every 6 hours.

For level II analgesics: e.g. paracetamol + codeine: there is a risk of sedation or increased risk of respiratory depression when combined with other central nervous system depressant drugs.

For level III analgesics: the risk of confusion must be taken into account in the elderly.

Conclusion :

In dentistry, we must try to prescribe as little as possible. On a clinical level , it is important to think about adapting the medication to the patient’s weight. On a biological level , the main parameter to take into account is creatinine clearance.

DRUG PRESCRIPTION IN ELDERLY SUBJECTS

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DRUG PRESCRIPTION IN ELDERLY SUBJECTS