Class 10- geri Flashcards
ABSORPTION
Slower oral absorption
o gastric pH
o intestinal motility
o concentration of proteins responsible for
active transport
Other factors : number of medications, eating
habits, positioning, comorbidities (dysphagia, GERD)
* Clinical impact is not significant
IV routeo Can cause peak effects
IM route: Painful in those with small muscles o Erratic Absorption
Transdermic route o Depending on skin integrity
DISTRIBUTION
o lean body mass
o a lot fat body mass (even if small weight!):
FAT SOLUBLE DRUGS: With repeated dosing, drugs can accumulate in fat - distribution volume and half-life
E.g. antidepressants, antipsychotics, benzodiazepines
o total body water small:
WATER-SOLUBLE DRUGS
- distribution volume
- risk of dehydration and adverse effects E.g. lithium
serum albumine: Especially if undernutrition
• unbound concentration of the drug
• E.g. phenytoin, valproate, NSAIDs, warfarin
- Significant clinical impact
METABOLISM
o PHASE I REACTIONS
• Metabolism affected by age
• E.g. accumulation of diazepam and risk of adverse effects
o PHASE II REACTIONS
o Metabolism unaffected with age
• Medications metabolized through glucuronidation are preferred in geriatrics (e.g. oxazepam)
ELIMINATION
o GFR o drug elimination o drug half-life • increase therapeutic and adverse effects of drugs o decreased dose often needed
PHARMACODYNAMICS
Elderly patients have greater psychotropic drug effects than younger patients given the same dose of medication
o greater sensitivity to drugs
o higher concentration at CNS receptors
o Receptor changes with aging
• Cholinergic system : M1 signal transduction, cholinergic activity
• sensivity to anticholinergic effects
DRUG INTERACTIONS ANTIPSYCHOTICS
• Clozapine + benzodiazepines • Antipsychotics + levodopa – Good choice quetiapine, clozapine • Increased QTc interval – Especially ziprasidone
Orthostatic hypotension- ANTIPSYCHOTICS
- Less tolerance than adults
- Risk of falling
- Choose those who have a low affinity for the alpha 1 receptor
- E.g. aripiprazole, lurasidone
- Use a small dose, divide the number of intakes, gradually increase the dose
CHOOSING AN ANTIPSYCHOTIC
1st generation (EPS) vs 2nd / 3rd generation (metabolic effects) - Long-acting injectables (LAI) can be used
ACCORDING TO COMORBIDITIES - Diabetes : ✓Best option aripiprazole ✗Avoid olanzapine / clozapine - Glaucoma : ✗Avoid antipsychotics with anticholinergic effects - Parkinson’s disease ✓Best options quetiapine ou clozapine
ANTIDEPRESSANTS SIADH
Syndrome of inappropriate ADH secretion
- Hyponatremia
- Change in mental status
- Serious consequences if hyponatremia not treated = coma, death
- Usually within the first 2 weeks of treatment
- Serum sodium should be checked before the treatment is treated, and at week 1 and 2 after treatment begins
ANTIDEPRESSANTS Bleeding
- Platelet dysfunction
- Dose-related effect
- Increased riks:
- History of GI bleeding
- Coagulation disorder
- NSAIDs
Heart conducting disorders ANTIDEPRESSANTS
Heart conducting disorders - Especially with tricyclic antidepressants (risk of arrhythmia) QTc prolongation - Maximum dose if > 65 ans : - Citalopram 20 mg die - Escitalopram 10 mg die
Choosing an antidepressant
✓Best options SSRI (except paroxetine) or SNRI
- My favourite = sertraline
- Respect maximum doses for citalopram and escitalopram
- Consider ECT
✗Avoid :
✗Paroxetine (anticholinergic effects)
✗Tricyclic antidepressants (anticholinergic effects, cardiac toxicity, drug interactions)
- MAOI (adverse effects, drug interactions)
DRUG INTERACTIONS MOOD STABILIZERS
• Several factors can influence the serum
concentration
– Denutrition
– Dehydration
– Interactions with other drugs
– Free (unbound) serum concentration may be relevant for valproate
MOOD STABILIZERS
Choosing a mood stabilizer
Bipolar disorder : generally the same as for the adult population
- Chronic use of a mood stabilizer :
- Gradual dose reduction is usually required according to liver / kidney function
- Lithium and valproate
- Prefer administration once a day at bedtime
- Aim for the bottom of the therapeutic range (e.g. 0.4 to 0.8 mmol/L for lithium)
BENZODIAZEPINES DRUG INTERACTIONS
• Cumulative adverse effects during concurrent use with other psychotropic drugs
• Excessive sedation
• Risk of falling
– Cognitive impairment
Choosing a benzodiazepine
- Always consider other alternatives. If a benzodiazepine MUST be used :
✓Best options benzodiazepines metabolized by glucuronidation - Lorazepam, oxazepam, temazepam
✗ Other benzodiazepines metabolized by oxidation / long half-life / active metabolites
✗Other sedatives / hypnotics to avoid :
✗Barbiturates: risk of addiction, abuse
✗Over-the-counter antihistamines: e.g. diphenhydramine - Non-benzodiazepine receptor agonists (e.g. zopiclone) : more favourable side effects profile but still not recommended according to Beers criteria
PRINCIPLES OF DRUG THERAPY REASSESSMENT IN ELDERY
- Indication of drugs
- Recent modification to pharmacotherapy
- Barriers to adherence
- Adverse effects
- Drug cascade
- Drug interactions
- Potentially inappropriate drugs
- Age-appropriate dosage
- Prioritize interventions
INDICATION OF DRUGS
Reason for consultation? Treatment for every health problem? Indication for each prescribed drug? Efficiency? - Duplication?