Prescriptions and drug interactions in the elderly
Introduction
The elderly person combines a series of factors that expose him to a high risk of adverse drug reactions including fragility, polymedication, altered pharmacokinetics and/or modified pharmacodynamics.
A few basic precautions should help reduce this risk and any doctor/dentist who frequently deals with elderly people should not only know them from a theoretical point of view, but above all apply them in practice.
- Reminder on the geriatric patient
True geriatric patient = age >75 years (senescence phenomena) + several chronic disabling pathologies + possible socio-economic problems.
- Pharmacokinetic and pharmacodynamic changes
- Pharmacokinetic changes (physiology of the body)
- Altered liver metabolism
- Decreased kidney function
- Pharmacodynamic changes (action of the drug on the body, therefore capacity of target organs to respond to drugs)
- Decreased responsiveness to drugs acting on B systems
adrenergic
- Increased sensitivity of the central nervous system to psychotropic drugs
- Drug prescriptions
- Prescription terms:
Overconsumption or “overuse”: Use of prescribed medications
the absence of indication or demonstrated efficacy.
Underuse: Failure to establish effective drug treatment in patients
subjects with a pathology for which one or more drug classes have shown their effectiveness.
Misuse: Use of medications with potentially dangerous
exceed expected benefits.
- Drug prescriptions
- Most prescribed drugs in the elderly:
- Cardiovascular drugs
- Central nervous system drugs and psychotropic drugs
- Digestive system medications
- Locomotor system drugs
- Painkillers: all levels
- Most frequently prescribed drugs in oral medicine:
Anti-infectives, anti-inflammatories, analgesics, antifungals, antivirals, hyposialia correctors, antiemetics, antihistamines, anesthetics, vasoconstrictors.
- Drug interaction
- Definition of a drug interaction:
Drug interaction is when two drugs A and B, administered simultaneously to a patient, drug A (called precipitant) interferes with the pharmacokinetics and/or pharmacodynamics of drug B (called object) 43 thus leading to a modification of the clinical effects of drug B (ANSM, 2019).
- Classification of drug interactions:
The most widely used is the ORCA classification (OpeRational ClassificAtion of Drug
interaction) :
| Category 1 | The risks outweigh the benefits, therefore an absolute contraindication. |
| Category 2 | Association not recommended, choose other molecules preferably. |
| Category 3 | Possible association but with precautions for use (clinical and biological monitoring, modification of dosages, etc.) |
| Category 4 | Possible association without special precautions for use (no significant clinical effects). |
| Category 5 | No interactions between drugs. |
TAB1. ORCA CLASSIFICATION (OPERATIONAL CLASSIFICATION OF DRUG INTERACTION)
Source: Hansen PD; Horn JR; Hazlet TK ORCA: OpeRational Classification of Drug interactions
- Anti-infectives
Penicillins:
| Associated molecules | Clinical consequences | Interaction Category | What to do |
| +methotrexate | increased liver toxicity + decreased renal excretion of methotrexate | 2 | Association not recommended |
| + allopurinal | Increased skin reaction | 4 | Take into consideration |
| +mycophenolate mofetil | Decreased efficiency due to decreased acid concentration | 4 | Take into consideration |
TAB2. INTERACTION OF PENICILLINS
Source: ANSM; thesaurus of drug interactions; version September 2019
Macrolides:
| Associated molecules | Clinical consequences | Category of interaction | Conduct to follow |
| + colchicine | Significant increase in side effects | 1 | Absolute contraindication |
| +Dihydroergotamine | Ergotism and necrosis of the extremities | 1 | Absolute contraindication |
| + ergotamine | Ergotism and necrosis of the extremities | 1 | Absolute contraindication |
| + AVK | Increased risk of bleeding | 3 | Precautions for use: INR and adaptation of AVK dosage |
TAB3. MACROLIDE INTERACTIONS
Source: ANSM; thesaurus of drug interactions; September 2019 version.
Lincosamides (clindamycin lincomycin):
| Associated molecule | Clinical consequence | Interaction Category | What to do |
| + curares | If administered parenterally, potentiates the effects of curare | 3 | Monitoring the degree of curarization before administration |
TAB.4 INTERACTIONS OF LINCOSAMIDES
Source: ANSM; thesaurus of drug interactions; version September 2019
Clindamycin
| Associated molecule | Clinical consequence | Interaction Category | What to do |
| + AVK | Increased risk of bleeding | 3 | Monitoring of INR and adaptation of AVK dosage |
| +(cyclosporine or tacrolimus) | Decreased immunosuppression | 3 | Serum dosage of cyclosporine and dosage adjustment |
TAB5. INTERACTIONS OF CLINDAMYCIN
Source: ANSM; thesaurus of drug interactions; September 2019 version.
Metronidazole
TAB6. INTERACTIONS OF
METRONIDAZOLE
SOURCE: ANSM; THESAURUS OF DRUG INTERACTIONS; SEPTEMBER 2019 VERSION
Pristinamycin
| Associated molecule | Clinical consequence | Interaction Category | What to do |
| + AVK | Increased risk of bleeding | 3 | INR measurement and AVK dosage adjustment |
| + colchicine | Increased side effects of colchicine | 1 | Absolute contraindication |
| +immunosuppressants | Increased plasma concentration of Is | 3 | Serum IS dosage and IS dosage adjustment |
TAB7. INTERACTIONS OF PRISTINAMYCIN
SOURCE: ANSM; THESAURUS OF DRUG INTERACTIONS; SEPTEMBER 2019 VERSION
Cyclines:
TAB8. INTERCATIONS OF CYCLINES
SOURCE: ANSM; THESAURUS OF DRUG INTERACTIONS; SEPTEMBER 2019 VERSION
Anti-inflammatories:
AIS (cortisone, prednisone, prednisolone, betamethasone):
- Enzyme inducers phenytoin carbamazepine…
- Anticoagulants lead to an increased risk of bleeding
- Antiarrhythmics and digitalis: increased toxicity of these molecules
Prescriptions and drug interactions in the elderly
NSAIDs:
They have a significant binding to plasma proteins and therefore present numerous drug interactions:
- AVK, heparin, antiplatelet agents: increased risk of bleeding
- Lithium increased lithium levels
- Hypoglycemic sulfonamides NSAIDs potentiate the effects of these molecules
Painkillers:
Paracetamol:
| Associated molecule | Clinical consequence | Interaction Category | What to do |
| + AVKs | Increased effect of AVKs | 3 | Adjust the dosage of AVKs |
| +enzyme inducers | Decreased analgesic effect and increased liver toxicity of paracetamol | 3 | Prefer another analgesic or a low dose (2g/day) for a short period. |
TAB9. PARACETAMOL INTERACTIONS
Source: ANSM; thesaurus of drug interactions; September 2019 version.
Antivirals (acyclovir (zovirax) and valaciclovir (zelitrex).
| Associated molecule | Clinical consequence | Interaction Category | What to do |
| + nephrotoxic drug | Increased nephrotoxicity | 3 | Monitoring of renal function and adaptation of antiviral dosage |
| +immunosup pressor, probenecid, mofetil | Increased plasma concentration of the antiviral | 3 | Plasma dosage and dosage adjustment |
TAB.10 INTERACTIONS OF ANTIVIRALS
Source: ANSM; thesaurus of drug interactions; version September 2019
Local anesthetics:
(Articaine, Mepivacaine, Lidocaine, Procaine)
| Associated molecule | Clinical consequence | Interaction Category | What to do |
| + guanethidine and related drugs (antiglaucomatous) | Decreased clinical efficacy | 1 | Absolute contraindication |
| +Antidepressants (MAOIs, imipramines, serotonergic, noradrenergic) | Increased clinical effects | 3 | Clinical monitoring, reduce the dose of anesthetic and the injection speed |
| + halogenated volatile anesthetics (used during GA) | Increased cardiac responsiveness | 3 | Idem |
TAB.11 INTERACTIONS OF LOCAL ANESTHETICS (ARTICAINE, MEPIVACAINE, LIDOCAINE,
PROCAINE)
Source: ANSM; thesaurus of drug interactions; September 2019 version.
Prescriptions and drug interactions in the elderly
- Essential prerequisite before any prescription
- Patient-related prerequisites:
- The precise and concise diagnosis
- The patient’s hydration status.
- The patient’s nutritional status
- Kidney function
- Liver function
- All current treatments
- Associated pathologies
- Cognitive abilities
- Prerequisites related to the prescribed molecules:
- The predominant elimination pathway
- The duration of action of the drug
- The hydrophilic or lipophilic character of the molecule
- The therapeutic margin of the molecule
- Adverse, pharmacological (known) effects as well as contraindications
indications
- The medical service provided
- The dosage form.
- The appropriateness or otherwise of the molecule.
- Clinical approach before any prescription
- Gathering information through anamnesis : History
medical and surgical, atopic terrain…
- Make a precise and concise diagnosis : any prescription must be
justified.
- Patient classification by category :
*Category 1: healthy patient (senescence phenomena only)
*Category 2: patient with comorbidity and/or polymedication: true so-called “geriatric” patient.
- Compliance with the following principles :
*Limit yourself only to necessary prescriptions.
*Prevent drug-induced iatrogenesis (dosage adaptation,
verification of interactions, respect of contraindications).
*Choice of the dosage form best suited to the patient.
*Ensure proper compliance: clear, legible prescription explained to the patient.
- Write the prescription
*Easy to read,
*As explicit as possible
*In duplicate
*Verbal explanations to the patient.
Prescriptions and drug interactions in the elderly
Conclusion
The dental surgeon in particular, as part of his activity, is required to issue curative prescriptions (exceptionally preventive) which almost never last more than 15 days (short term).
These prescriptions mainly concern the following therapeutic classes : level I and II analgesics, antibiotics , antifungals, local antivirals, anti-inflammatories, local anesthetics, mouthwashes. To respect the principle of non-harm, a rigorous clinical approach must be taken before any prescription, particularly in patients over 65 years of age.
Prescriptions and drug interactions in the elderly
Deep cavities may require root canal treatment.
Interdental brushes effectively clean between teeth.
Misaligned teeth can cause chewing problems.
Untreated dental infections can spread to other parts of the body.
Whitening trays are used for gradual results.
Cracked teeth can be repaired with composite resins.
Proper hydration helps maintain a healthy mouth.