Can a patient with impaired renal function take Tymlos (abaloparatide) for osteoporosis (OP) prior to spinal fusion surgery?

Can a Patient with Elevated Creatinine Take Tymlos for Osteoporosis Prior to Spinal Fusion Surgery?

Yes, a patient with elevated creatinine can take Tymlos (abaloparatide) prior to spinal fusion surgery without dose adjustment, even with moderate to severe renal impairment, though patients with severe renal dysfunction require monitoring for adverse reactions. 1

Renal Safety Profile of Tymlos

• No dosage adjustment is required for patients with mild, moderate, or severe renal impairment when using Tymlos, according to the FDA label 1

• Abaloparatide exposure increases in renal impairment: Cmax increases 1.4-fold and AUC increases 2.1-fold in severe renal impairment (CrCl 15-29 mL/min) compared to normal renal function 1

• Patients with severe renal impairment should be monitored for adverse reactions due to increased drug exposure, but treatment is not contraindicated 1

• Clinical trial data from the ACTIVE study demonstrated that patients with eGFR <60 mL/min showed no meaningful differences in efficacy or safety outcomes compared to those with normal renal function 2

Superiority of Tymlos for Spinal Fusion in Osteoporosis

Preoperative treatment with teriparatide (the class to which abaloparatide belongs as a PTHrP analog) is associated with higher fusion rates, earlier fusion, and lower screw loosening rates compared to bisphosphonates or no treatment 3

• The Congress of Neurological Surgeons provides a Grade B recommendation that preoperative osteoporosis treatment with teriparatide increases bone mineral density, induces earlier and more robust fusion, and may improve select patient outcomes 3

• Teriparatide demonstrated significantly higher fusion rates (82% at 8 months) compared to bisphosphonates (68% at 10 months, p<0.05) in prospective studies of patients undergoing instrumented fusion 3

• The incidence of pedicle screw loosening was significantly lower with teriparatide (7%) compared to bisphosphonates (13%) or no treatment (15%, p<0.05) 3

• Meta-analysis shows teriparatide therapy results in patients being 2.05 times more likely to experience successful fusion during long-term monitoring compared to bisphosphonates (OR 2.05,95% CI 1.17-3.59, p=0.01) 4

Renal Impairment-Specific Considerations for Tymlos

• Hypercalcemia occurred in 3.6% of abaloparatide-treated patients with eGFR <60 mL/min versus 10.9% with teriparatide (p=0.008), demonstrating a superior safety profile for abaloparatide in renal impairment 2

• The incidence of hypercalcemia (albumin-corrected serum calcium ≥10.8 mg/dL at 4 hours post-injection) was higher in patients with mild or moderate renal impairment (4%) compared to normal renal function (0%) 1

• Monitor serum calcium levels in patients with renal impairment, particularly those with eGFR <60 mL/min, as they may experience increased hypercalcemia risk 1, 2

• CT scans in 376 patients revealed no evidence of increased renal calcification with abaloparatide treatment 2

Contraindications and Cautions with Alternative Agents

• Bisphosphonates are contraindicated in patients with GFR <30 mL/min, making them unsuitable for patients with severe renal dysfunction 5

• For patients with moderate to severe CKD without signs of renal osteodystrophy, oral bisphosphonates (risedronate) may be considered with strict monitoring of renal function and PTH, but this requires certainty that adynamic bone disease is not present 5

• NSAIDs should be avoided in patients with estimated creatinine clearance <50 mL/min according to the American Heart Association, which is relevant for perioperative pain management 6

Clinical Algorithm for This Patient Population

Step 1: Assess renal function

• Calculate eGFR or creatinine clearance to determine severity of renal impairment 1

Step 2: Confirm osteoporosis diagnosis

• Perform DEXA scan (T-score <-2.5), CT scan (Hounsfield units <97.9), or check vitamin D3 level (<20 ng/mL) 3

Step 3: Initiate Tymlos without dose adjustment

• Administer 80 mcg subcutaneously daily regardless of renal function 1

Step 4: Monitor for adverse reactions

• Check serum calcium at 4 hours post-injection, particularly in patients with eGFR <60 mL/min 1
• Monitor for nausea, dizziness, hypercalcemia, and upper respiratory tract infections, which may be more frequent with renal impairment 2

Step 5: Ensure adequate vitamin D and calcium

• Correct vitamin D deficiency before initiating therapy 7
• Provide calcium (1200 mg/day) and vitamin D3 (800-1000 IU/day) supplementation 7

Common Pitfalls to Avoid

• Do not withhold Tymlos based solely on elevated creatinine - the FDA label explicitly states no dose adjustment is needed even in severe renal impairment 1

• Do not substitute bisphosphonates in patients with severe renal dysfunction (GFR <30 mL/min) - they are contraindicated in this population 5

• Do not assume teriparatide and abaloparatide have identical renal safety profiles - abaloparatide demonstrates lower hypercalcemia rates in renal impairment 2

• Avoid using NSAIDs for perioperative pain management if creatinine clearance is <50 mL/min 6

• Recognize that patients with renal dysfunction undergoing spinal fusion have inherently higher perioperative morbidity (OR 3.82 for GFR 15-30 mL/min), making optimization of bone health even more critical 8