Can cinacalcet be used in elderly patients with secondary hyperparathyroidism?

Cinacalcet Use in Elderly Patients with Secondary Hyperparathyroidism

Cinacalcet should be used with caution in elderly patients with secondary hyperparathyroidism due to the increased risk of hypocalcemia and QT interval prolongation, but remains a viable treatment option when other therapies fail. 1, 2

Indications for Cinacalcet in Elderly Patients

Cinacalcet is indicated for elderly patients with:

• Persistent elevated PTH levels despite optimization of vitamin D and calcium therapy 2
• Severe hyperparathyroidism despite normocalcemia 1
• Hypercalcemic hyperparathyroidism that has failed to respond to other treatments 1
• Cases where parathyroidectomy is not feasible due to advanced age, frailty, or patient refusal 3

Treatment Algorithm for Secondary Hyperparathyroidism in Elderly

1. First-line approach: Optimize vitamin D levels (target >20 ng/mL) and ensure adequate dietary calcium intake 1, 2
2. Second-line approach: Adjust active vitamin D dosing and phosphate supplements 2
3. Third-line approach: Consider cinacalcet when:
   • PTH levels remain >500-800 pg/mL despite above measures
   • Patient has hypercalcemic hyperparathyroidism resistant to other treatments
   • Patient is not a surgical candidate due to age or comorbidities 1, 2, 3

Dosing and Monitoring in Elderly

• Starting dose: Lower starting doses are prudent in elderly patients (e.g., 30 mg daily) 4
• Dose titration: Increase gradually based on PTH and calcium levels, with more cautious titration in patients ≥75 years 3
• Monitoring frequency:
  • Check calcium, phosphorus, and PTH levels every 1-3 months
  • More frequent monitoring (every 2-4 weeks) during dose titration 2
  • Monitor for QT interval prolongation, especially in elderly with cardiac comorbidities 1

Efficacy in Elderly Population

Research specifically examining cinacalcet in elderly patients has shown:

• Effective normalization of calcium in 72.4% of elderly patients (mean age 77 years) 3
• PTH normalization in approximately 33.4% of elderly patients 3
• Patients ≥75 years may show significant PTH reduction (-6.7 pmol/L) 3
• Patients with higher comorbidity scores (Charlson Comorbidity Index >5) may require lower doses to achieve biochemical targets 3

Special Considerations and Cautions in Elderly

• Risk of hypocalcemia: Elderly patients may be more susceptible to severe hypocalcemia, including hungry bone syndrome 5
• QT interval prolongation: Increased risk in elderly with pre-existing cardiac conditions 1
• Medication interactions: Elderly patients often take multiple medications; cinacalcet strongly inhibits CYP2D6, requiring dose adjustments of concomitant medications metabolized by this pathway 4
• Hepatic impairment: Dose reduction needed in elderly with moderate to severe hepatic impairment as exposure increases 2-4 fold 4
• Adherence concerns: Financial barriers may affect adherence, with higher discontinuation rates observed during Medicare Part D gap periods 6

When to Consider Parathyroidectomy Instead

Parathyroidectomy should be considered in elderly patients with:

• Persistent hypercalcemic hyperparathyroidism despite cinacalcet therapy 1
• Intolerance to cinacalcet due to adverse effects 2
• Good surgical candidates with severe, symptomatic hyperparathyroidism 2

Conclusion

While cinacalcet requires careful monitoring in elderly patients, it represents an important therapeutic option for those with secondary hyperparathyroidism who cannot undergo parathyroidectomy due to advanced age, comorbidities, or personal preference. The key is appropriate patient selection, cautious dosing, and vigilant monitoring for adverse effects, particularly hypocalcemia and QT interval prolongation.