Proton Pump Inhibitors (PPIs)

What They Are

The 6 Available PPIs

• Esomeprazole is the S-isomer of omeprazole (same molecule, improved bioavailability)
• Dexlansoprazole is the R-enantiomer of lansoprazole
• IV formulations exist for esomeprazole, pantoprazole, and omeprazole sodium

Mechanism in Detail

1. PPIs are prodrugs - inactive at neutral pH
2. After oral absorption, they diffuse into the parietal cell's acidic secretory canaliculi
3. Acid-catalyzed conversion produces an active sulfenamide that covalently binds to cysteine residues on H+/K+-ATPase
4. Because binding is irreversible, acid suppression lasts 24-48 hours despite the drug's plasma half-life of only 0.5-3 hours
5. Acid secretion only resumes after new pump synthesis (18+ hours)

How to Take Them Correctly

• Take 30-60 minutes before the first meal of the day (so peak drug levels coincide with maximal pump activity after meal stimulation)
• Food reduces bioavailability by ~50%, so take on an empty stomach
• In fasting state, only 10% of pumps are active - this is why taking them before eating matters
• Dose reduction is generally not needed for renal insufficiency or mild-moderate liver disease, but should be considered in severe hepatic impairment

Clinical Uses

Which PPI is "Best"?

• Esomeprazole 40 mg showed the highest mean 24-hour intragastric pH (4.0) and longest time pH >4 (14 hours) in crossover studies vs. pantoprazole 40 mg (pH 3.3, 10.1 hours) - making it slightly more potent by lab measures, though the clinical significance is debated
• Pantoprazole has fewest drug interactions and is preferred with clopidogrel (least CYP2C19 inhibition - does not reduce clopidogrel's antiplatelet effect as much)
• Omeprazole has the most drug interactions - it inhibits CYP2C19 and induces CYP1A2, affecting warfarin, phenytoin, diazepam, and others
• Rabeprazole has the highest pKa (5.0), which means it activates at less acidic conditions and may have a faster onset, and it is less dependent on CYP2C19 metabolism (more predictable in poor metabolizers)
• Dexlansoprazole has a dual delayed-release formulation with a longer Tmax, useful for patients with nocturnal symptoms, though overall acid suppression is comparable

Adverse Effects

• Generally very well tolerated; strong safety record
• Common: headache, nausea, abdominal pain, flatulence, diarrhea, constipation
• Long-term concerns: hypomagnesemia, increased risk of C. difficile infection, possible increased fracture risk, acute interstitial nephritis, vitamin B12 deficiency
• Rebound acid hypersecretion can occur after stopping - taper gradually over a few weeks

Drug Interactions Summary

Quick Practical Summary

• For most patients: any PPI at standard dose works equally well
• Need IV PPI: esomeprazole or pantoprazole
• On clopidogrel: prefer pantoprazole
• CYP2C19 poor metabolizers or need predictable levels: rabeprazole
• Nocturnal/breakthrough symptoms: dexlansoprazole (dual-release formulation)
• Most potent by pH data: esomeprazole 40 mg

• Omeprazole (Prilosec)
• Pantoprazole (Protonix)
• Esomeprazole (Nexium)
• Lansoprazole (Prevacid)
• Rabeprazole (Aciphex)

Diabetic Foot Treatment

Background & Pathophysiology

• Sensorimotor neuropathy - loss of protective sensation, muscle atrophy, structural deformity (claw/hammertoe)
• Autonomic neuropathy - dry skin, fissures
• Peripheral arterial disease (PAD) - ischemia impairs healing
• Immune dysfunction - impaired bacterial clearance
• Structural abnormalities - calluses, bunions, Charcot deformity create pressure points

Classification

• Risk of major amputation at 1 year
• Likely benefit of revascularization

• Grade 0 - no wound / pre-ulceration
• Grade 1 - shallow ulcer, no exposed bone (except distal phalanx), no gangrene
• Grade 2 - exposed bone, gangrene limited to digits, or shallow heel ulcer
• Grade 3 - extensive ulcer/gangrene, full-thickness heel ulcer

Treatment: The 6 Pillars

1. Glycemic Control

• Integration of endocrinology into the care team is essential
• HbA1c target ≤8% (not necessarily ≤7%) has been shown to predict avoidance of major amputation - a more liberalized approach may be appropriate
• Poor glycemic control directly impairs wound healing and immune function

2. Wound Care & Debridement

• Start with callus debridement - overlying callus hides the wound and blocks wound care products
• Wounds are probed to assess depth and bone penetration ("probe-to-bone" test)
• 3-view X-ray of foot to evaluate for osteomyelitis and structural deformities
• MRI is the most sensitive modality for bone involvement
• Dirty/infected wounds are left open initially for serial debridement, then closed in staged fashion
• For wounds with exposed tendon or bone, Integra dermal regeneration template can be used, followed by split-thickness skin grafting (12-month healing rate ~79%)

3. Offloading Pressure

• Removing mechanical pressure is fundamental - without offloading, ulcers will not heal
• Options: total contact casting (gold standard), removable cast walkers, therapeutic footwear, custom orthotics
• Structural deformities causing recurring ulcers may require surgical correction (excision + foot rebalancing) for long-term resolution

4. Infection Management

• Causative organisms: S. aureus, beta-haemolytic streptococci, aerobic Gram-negative bacilli
• Pseudomonas is over-represented - empirical therapy for severe infections must cover it
• Anaerobes (add metronidazole for abscesses/devitalized tissue)

• Mild/superficial infection: oral antibiotics guided by culture
• Grade 2-3 infection (deep tissue): IV parenteral antibiotics + hospitalization
• Antibiotics should be guided by deep tissue cultures (not surface swab cultures - these are unreliable)
• Simple toe amputation: 2-week oral antibiotics post-op
• Metatarsal resection (ray/proximal amputation): 4-6 weeks antibiotics regardless of margins

• Drainage of abscesses
• Debridement of necrotic soft tissue and bone
• Digit or ray amputation when bone is infected

5. Revascularization (for Ischemia)

• Full vascular assessment is mandatory in all patients with poor peripheral pulses
• Angiography + endovascular intervention for wounds with toe pressure 60-80 mm Hg that fail to heal in 4-6 weeks
• Near all grade 1+ ischemia are referred for angiography
• Options:
  • Endovascular (angioplasty/stenting) - preferred for tibial disease; lower perioperative risk
  • Open bypass (single-segment saphenous vein graft) - for long-segment or heavily calcified lesions not crossable endovascularly
• Hyperbaric oxygen therapy - last resort for severe forefoot ischemia not amenable to surgical/endovascular treatment; indications: osteomyelitis, gangrene, or open wound with inadequate perfusion

6. Amputation (when necessary)

• Required for extensive infection, gangrene, or tissue not salvageable
• Minor amputations: toe, ray, or transmetatarsal amputation (limb-preserving)
• Major amputations: below-knee (BKA) or above-knee (AKA) when more distal options are exhausted
• Excision must be adequate to remove all infected material; excess bone resected for tension-free closure
• In extensive peripheral neuropathy, BKA in a better-sensate area may be more appropriate than foot-level amputation

Advanced/Adjunctive Therapies

Multidisciplinary Team Approach

• Vascular surgery
• Surgical podiatry
• Wound care nursing
• Endocrinology
• Infectious disease (complex infections)
• Plastic surgery / orthopaedic surgery (as needed)

Prevention (Long-Term)

• Regular foot inspection (daily self-exam)
• Custom therapeutic footwear
• Strict glycemic control
• Smoking cessation
• Patient and family education on foot care

Key point: Early recognition and multidisciplinary management are the most effective tools for preventing limb loss. Approximately 85% of amputations are preceded by an ulcer - most are preventable with proper care.

Recent Clinical Guidelines on Diabetic Foot Care

1. IWGDF 2023 Guidelines (Published 2024) - The Gold Standard

A. Prevention of Foot Ulcers

• Screen all diabetic patients annually for loss of protective sensation (LOPS) and peripheral artery disease (PAD); screen higher-risk patients more frequently
• Educate patients on appropriate foot self-care and not walking barefoot
• Treat any pre-ulcerative lesions (callus, blister, fissure) promptly
• Prescribe therapeutic footwear with demonstrated plantar pressure-relieving effect to prevent plantar ulcer recurrence
• Consider supervised foot-ankle exercise programme to reduce ulcer risk factors in low-to-moderate risk patients
• Consider flexor tendon tenotomy in non-rigid hammertoe with pre-ulcerative lesion
• Provide integrated multidisciplinary foot care for moderate-to-high risk patients

B. Offloading Foot Ulcers

1. Non-removable knee-high offloading device (total contact cast) = first choice for neuropathic plantar forefoot/midfoot ulcer
2. Removable knee-high or ankle-high device = second choice if contraindication/intolerance to non-removable device
3. Therapeutic footwear + felted foam = third choice if devices unavailable
4. If non-surgical offloading fails: consider Achilles tendon lengthening, metatarsal head resection, joint arthroplasty, or metatarsal osteotomy
5. For neuropathic digit ulcers from flexible toe deformity: digital flexor tendon tenotomy

C. Wound Healing Interventions

• Sucrose octasulfate dressings (TLC-NOSF)
• Negative pressure wound therapy (NPWT/VAC) for post-operative wounds
• Placental-derived products
• Autologous leucocyte/platelet/fibrin patch
• Topical oxygen therapy
• Hyperbaric oxygen therapy

D. Classification of Foot Ulcers

• SINBAD (Site, Ischaemia, Neuropathy, Bacterial infection, Area, Depth) - first choice for communication between clinicians and for auditing population outcomes
• WIfI (Wound, Ischaemia, foot Infection) - alternative for stratifying healing likelihood and amputation risk when equipment/expertise available
• IDSA/IWGDF - for characterizing infected ulcers

E. Diabetic Foot Infections (IWGDF/IDSA Joint Guideline)

• Diagnosis and classification of soft tissue vs. bone infections
• Severity grading (mild/moderate/severe) using IDSA/IWGDF criteria
• How to collect microbiological samples correctly (deep tissue, not surface swabs)
• Empiric vs. culture-directed antimicrobial therapy
• Surgical indications and approach
• Adjunctive treatments - which work and which don't
• Emphasis: individualize treatment based on infection severity and comorbidities including PAD

⚠️ Note: An erratum was published for this guideline (PMID: 38809257, July 2024) - check the correction before clinical use.

F. Charcot Neuro-osteoarthropathy

• First-ever IWGDF guideline dedicated to Charcot foot
• Covers diagnosis and treatment of active Charcot neuro-osteoarthropathy in diabetes
• GRADE-based systematic review methodology

2. ADA Standards of Care in Diabetes - 2026

• Annual comprehensive foot exam for all diabetic patients (inspection, assessment of protective sensation, vascular assessment)
• No-risk/low-risk: education and self-care
• Moderate-to-high risk (LOPS, PAD, structural deformity, Charcot): refer to foot care specialist for further evaluation and regular surveillance
• Urgent referral for any open ulceration, unexplained swelling, erythema, or increased skin temperature
• Treatment of foot infections should be individualized based on severity and comorbidities including PAD (references the IWGDF/IDSA 2023 joint guideline)
• Explicitly endorses the IWGDF 2023 practical guidelines (Schaper NC et al., PMID: 37243927)

3. Wound Healing Society (WHS) 2024 Update

• Updated USA-based guidelines from the Wound Healing Society
• Focuses specifically on DFU treatment algorithms
• Free access guideline

4. IWGDF/ESVS/SVS - Peripheral Artery Disease Guideline (2023)

• Joint guideline from IWGDF + European/American vascular surgery societies
• Covers vascular assessment, revascularization thresholds, and techniques specific to the diabetic foot

Summary Table