Neuropathic and Osteoarthritic Pain in Advanced CKD With Fall Risk
Mr. B is a 78-year-old man with painful diabetic peripheral neuropathy and knee osteoarthritis. His eGFR is 22 mL/min/1.73 m²; he takes apixaban for atrial fibrillation, amlodipine, and tamsulosin for benign prostatic hyperplasia. He has a history of angle-closure glaucoma. He tried gabapentin 300 mg at bedtime but developed confusion and stopped. He rates foot burning 7/10 and knee pain 6/10; PHQ-9 is 12. He asks for 'something stronger' and says acetaminophen 'does nothing.' Examination shows reduced vibration and pinprick in both feet and crepitus of the right knee. He lives alone and has fallen twice in the past year.
1. Select a pharmacologic approach for his neuropathic pain, explaining why you would avoid the common alternatives.
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The main constraints are severe renal impairment, glaucoma, benign prostatic hyperplasia, and falls. Duloxetine is not recommended with CrCl <30 and is contraindicated in uncontrolled narrow-angle glaucoma; nortriptyline is a poor choice because of glaucoma, urinary retention, and fall risk. Gabapentin caused confusion at 300 mg, but that does not permanently contraindicate it; if retried, start at 100 mg daily and titrate slowly. Pregabalin is renally dosed (e.g., 25 mg daily in CrCl <30) and may be an alternative, but it carries similar sedation and edema risks. Topical capsaicin or lidocaine may help localized foot pain but is impractical for diffuse neuropathy. I would choose a low-dose gabapentinoid with explicit fall precautions and shared decision-making, while adding nonpharmacologic care. I would not start an opioid for this indication.
2. How would you manage his knee osteoarthritis without oral NSAIDs or opioids?
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For knee osteoarthritis, acetaminophen up to 3 g/day is reasonable if hepatic function is normal; because he says it does nothing, I would assess adherence, timing, and expectations. Topical diclofenac gel has low systemic absorption but should be used cautiously in CKD; it is preferable to oral NSAIDs, which are contraindicated with eGFR 22 and apixaban. Intra-articular corticosteroid can provide short-term relief but requires glucose monitoring. Physical therapy, weight management, assistive devices, and heat may help. I would avoid tramadol because of renal dosing, seizure risk, and fall risk. If pain remains refractory, I would refer for orthopedic evaluation rather than escalating analgesics.
3. What monitoring and safety plan would you implement?
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I would monitor renal function, sedation, dizziness, peripheral edema, and falls at each titration. I would check glucose after any intra-articular steroid. I would screen mood and sleep, because PHQ-9 12 suggests depression that may amplify pain. I would reassess goals-function and sleep, not just pain score-and deprescribe if there is no meaningful benefit or if adverse effects outweigh benefits. I would coordinate with his pharmacist and primary care clinician and review his home for fall hazards.