What is the preferred choice between loratadine (Loratadine) and bilastine (Bilastine) for patients undergoing peritoneal dialysis with impaired renal function?

Bilastine is Preferred Over Loratadine in Peritoneal Dialysis Patients

For patients undergoing peritoneal dialysis, bilastine at the standard 20 mg daily dose is the preferred antihistamine choice, as it requires no dose adjustment despite renal impairment and maintains safety margins even with increased drug exposure. 1

Pharmacokinetic Rationale

Bilastine in Renal Impairment

• Bilastine can be safely administered at the standard 20 mg daily dose to patients with all degrees of renal insufficiency, including severe impairment (GFR ≤30 mL/min/1.73 m²), without requiring dose adjustments. 1
• Although bilastine exposure (AUC) increases progressively with worsening renal function—ranging from 737.4 ng·h/mL in healthy subjects to 1708.5 ng·h/mL in severely impaired patients—this increased exposure remains well within established safety margins. 1
• Renal excretion is the primary elimination route for bilastine, with the oral plasma clearance to renal clearance ratio remaining approximately equal across all renal function groups, indicating no compensatory alternative elimination pathways are activated even in severe renal insufficiency. 1
• The majority of bilastine is excreted within the first 12 hours, with elimination essentially complete by 72 hours, and the drug was well-tolerated across all renal impairment groups studied. 1

Loratadine Considerations

• While loratadine is primarily metabolized by the liver to an active renally cleared metabolite, previous studies have shown no differences in half-lives when comparing young adults with older adults or those with renal failure. 2
• However, the active metabolite's renal clearance pathway creates theoretical concerns in peritoneal dialysis patients, particularly those who are anuric or have minimal residual renal function. 2

Peritoneal Dialysis-Specific Factors

Drug Clearance Considerations

• Peritoneal dialysis contributes minimally to total body drug clearance for most medications, with peritoneal clearance being substantially lower than hemodialysis clearance. 3, 4
• The cumulative removal of renally excretable drugs in continuous ambulatory peritoneal dialysis (CAPD) patients can be higher than in hemodialysis patients between sessions due to the continuous nature of the therapy. 5
• Drug clearance is enhanced in patients receiving automated peritoneal dialysis compared with CAPD, and also in those with residual urine output compared to anuric patients. 5

Practical Dosing Algorithm

For peritoneal dialysis patients requiring antihistamine therapy:

1. First-line choice: Bilastine 20 mg once daily (no adjustment needed regardless of residual renal function or dialysis modality) 1

2. If bilastine is unavailable: Loratadine may be used at standard doses, though theoretical concerns exist regarding active metabolite accumulation in anuric patients 2

3. Monitor for: Enhanced antihistamine effects in patients with minimal residual renal function, though bilastine has demonstrated no sedative or cardiotoxic effects in clinical trials 1

Common Pitfalls to Avoid

• Do not assume that all second-generation antihistamines require dose adjustment in renal impairment—bilastine is unique in maintaining safety without adjustment even in severe renal insufficiency. 1
• Do not supplement antihistamine doses after peritoneal dialysis exchanges, as the quantity of drugs removed during peritoneal dialysis is substantially lower than hemodialysis and does not warrant supplementation. 5
• Do not reduce bilastine dosing based on creatinine clearance calculations—the increased exposure in renal impairment remains within therapeutic safety margins. 1
• Consider that residual renal function impacts drug clearance—patients with preserved urine output will have enhanced drug elimination compared to anuric patients, though this does not necessitate dose changes for bilastine. 5