Prescribing for the elderly

1. Prescribing for the elderly T. Walley SH Khoo

2. Drug Use in the Elderly Common • 70% of pts over 65 taking medication regularly • CVS 32% • Musculoskeletal 10% • GIT 8% • Respiratory 7% • Compliance high (75%)

3. But often poor in quality • 36% of hypnotics at greater than recommended doses • Potentially harmful interactions in 28% • Duplication 4% • Appropriateness of many of the other drugs? • Mostly (80%) repeat prescribing (– little review)

4. Prescribing Rates increasingno of prescription per head per year

5. Why increasing rates? • Less therapeutic nihilism about elderly e.g. hypertension • Better evidence of effect in the elderly • Increase in numbers of elderly and very elderly • Increasing patient demand perhaps? • Defensive behaviour by doctors?

6. Problems with Prescribing for the elderly • 10% of hospital admissions of elderly due to Adverse drug reactions • Inappropriate prescribing accounts for about 50% of these. • Large numbers of less severe adverse drug reactions, prompting GP visits, or poor compliance with therapy

7. Reasons for poor prescribing in elderly • Excessive response to symptoms • Demand (real or perceived) • Inappropriate response to nonmedical problems • Unrealistic expectations on part of patient or doctor • Prescribing by rule and not individualising • Inadequate review – failure to discontinue drugs (hospital v primary care)

8. Incremental prescribing: Example Dyspepsia Rx ranitidine BP Rx nifedipine More dyspepsia… and so on Ankle swelling Rx diuretic Ankles still swollen, low K+ Increase does of diuretic, add K+supplements Gout – Rx diclofenac, allopurinol

9. Clinical Pharmacology in the elderly • Pharmacokinetic differences • Drug absorption unchanged • Decreased renal clearance of many drugs (Li+, gentamicin, digoxin) • Hepatic clearance decreased (sufficient reserve for this to only be a problem rarely, except perhaps decreased first pass metabolism of many drugs) • Different water/fat ratios - higher plasma concentrations of some (water soluble) drugs (eg digoxin)

10. Clinical Pharmacology in the elderly • Pharmacodynamic differences • Increased susceptibility to some drug effects despite similar plasma concentrations eg benzodiazepines, antihypertensives • ?Alterations in receptor density in some cases • Decreased homeostatic reserves e.g. postural hypotension

11. Clinical Pharmacology in the elderly • Comorbidities • Other drug therapies and interactions more likely • Adverse drug reactions more common in elderly than in younger patients

12. Studying Drugs in the Eldelry • In the past it was not necessary to test a drug in elderly even though they were likely to be major users • eg benoxaprofen – withdrawn NSAID – caused hepatotoxicity and photosensitivity in elderly but not in younger trial subjects • Importance of reporting adverse drug reactions

13. Compliance/Adherence/Concordance • Will the patient take the tablets? • Many elderly deterred by • Adverse effects • Complex regimens with multiple drugs • Poor information (written better than verbal) • Confusion between hospital and primary care • Intelligent non-compliance

14. Residential and Nursing Home Patients • Very high levels of drug use • For whose benefit? Patient or staff…? • eg hypnotics, psychotropics • Drugs continues when original indication long passed – inadequate review

15. Key Principles for Prescribing in the Elderly (or anyone else) • Careful clinical assessment • Of all the patient’s problems, not symptom by symptom • If in doubt, don’t prescribe • Start with low doses • Increase in small increments • Keep regimens simple • Avoid polypharmacy as much as possible