24.2 Polypharmacy, Deprescribing & Pressure Ulcers

4. Safe Prescribing & Polypharmacy in the Elderly

Polypharmacy (commonly defined as the concurrent use of ≥5 regular medications) is present in >40% of older inpatients, driving adverse drug reactions (ADRs), drug-drug interactions, non-adherence, delirium, and hospital readmissions.

Age-Related Pharmacokinetics & Pharmacodynamics

Explicit Prescribing Criteria: Beers & STOPP/START

• STOPP (Screening Tool of Older Persons' Prescriptions): Identifies potentially inappropriate medications (PIMs) in older adults.
• START (Screening Tool to Alert to Right Treatment): Identifies evidence-based prescribing omissions (e.g. statin post-stroke, ACE inhibitor in heart failure, bisphosphonates in severe osteoporosis).

High-Risk Drug Classes in Geriatric Practice

1. Anticholinergic Agents (Anticholinergic Burden [ACB] Score):
   • Common culprits: Amitriptyline, oxybutynin, chlorphenamine, cyclizine, hyoscine, paroxetine, prochlorperazine.
   • High ACB scores directly cause acute delirium, accelerated cognitive decline, dry mouth, blurred vision, acute closed-angle glaucoma, constipation, and acute urinary retention.
2. Non-Steroidal Anti-Inflammatory Drugs (NSAIDs):
   • Inhibit renal prostaglandin synthesis (PGI2, PGE2), inducing afferent arteriolar vasoconstriction and precipitating acute kidney injury (AKI).
   • Promote renal sodium and water retention, exacerbating congestive cardiac failure and severe hypertension.
   • Synergistic ulceration and life-threatening upper GI bleeding.
   • "The Triple Whammy": Concurrent combination of NSAID + ACE inhibitor/ARB + Diuretic, producing acute tubular necrosis via simultaneous afferent arteriolar constriction (NSAID), efferent arteriolar vasodilation (ACEi), and volume depletion (diuretic).
3. Benzodiazepines & Z-Drugs (Zopiclone, Zolpidem):
   • Exaggerated GABAergic sensitivity produces psychomotor slowing, daytime somnolence, confusion, ataxia, and a 2-fold increased risk of falls and femoral neck fractures.
4. Sulfonylureas (Gliclazide, Glimepiride):
   • Prolonged half-life in renal impairment stimulates prolonged endogenous insulin secretion, triggering severe, protracted, fatal hypoglycaemia. Gliclazide is preferred over glibenclamide (glibenclamide is strictly contraindicated due to long-acting active metabolites).

5. Pressure Ulcers: Staging & Prevention

Pressure ulcers (bedsores/pressure injuries) are localized injuries to the skin and underlying tissue, typically over bony prominences, resulting from sustained pressure, friction, or shear forces.

EPUAP / NPUAP / NICE Staging System

EPUAP/NPUAP Pressure Ulcer Staging Classification
  │
  ├── CATEGORY I: Non-Blanchable Erythema of Intact Skin
  │     └── Intact skin with non-blanching redness over bony prominence; area may be painful, firm, soft, or warm
  │
  ├── CATEGORY II: Partial-Thickness Skin Loss
  │     └── Loss of dermis presenting as shallow open ulcer with red-pink wound bed; OR intact/ruptured serum blister
  │
  ├── CATEGORY III: Full-Thickness Skin Loss
  │     └── Subcutaneous fat may be visible; bone, tendon, and muscle are NOT exposed; slough may be present
  │
  ├── CATEGORY IV: Full-Thickness Tissue Loss with Exposed Supporting Structures
  │     └── Exposed bone, tendon, or muscle; slough or eschar often present; includes undermining/tunnelling (osteomyelitis risk)
  │
  ├── UNSTAGEABLE: Full-Thickness Skin or Tissue Loss — Depth Unknown
  │     └── Base of ulcer completely covered by slough (yellow/tan/grey) or eschar (tan/brown/black), obscuring true depth
  │           *Stable, dry, intact eschar on heels serves as biological cover and should NOT be debrided*
  │
  └── SUSPECTED DEEP TISSUE INJURY (DTI): Depth Unknown
        └── Purple or maroon localized area of discoloured intact skin or blood-filled blister from underlying soft tissue shear

Risk Assessment & Evidence-Based Prevention

• Risk Scoring Scales: Waterlow Score and Braden Scale evaluate sensory perception, moisture, physical activity, mobility, nutritional status, and friction/shear.
• Preventative Interventions:
  • High-Specification Foam Mattresses: First-line for all patients at elevated risk.
  • Alternating-Pressure Dynamic Mattresses / Overlays: Indicated for high-risk patients (Category III/IV ulcers or severe immobility).
  • Scheduled Repositioning: Minimum 2- to 3-hourly repositioning schedule (e.g. 30-degree tilt) to relieve pressure on sacrum and greater trochanters.
  • Skin Barrier Films & Moisture Management: Prevent maceration from incontinence.
  • Nutritional Optimization: Ensuring adequate dietary protein (1.2–1.5 g/kg/day), caloric intake, and hydration.