Bilastine Dosing and Administration
Bilastine should be taken 20 mg once daily for adults and adolescents ≥12 years, or 10 mg once daily for children aged 6–11 years weighing ≥20 kg, and must be taken on an empty stomach—at least 1 hour before or 2 hours after food or fruit juice—to ensure proper absorption. 1, 2
Standard Dosing by Age and Weight
Adults and Adolescents (≥12 years)
- Dose: 20 mg orally once daily 2, 3
- Timing: Must be taken on an empty stomach (at least 1 hour before or 2 hours after meals) 1
- Indications: Allergic rhinoconjunctivitis and chronic urticaria 2, 3
Children (6–11 years, weighing ≥20 kg)
- Dose: 10 mg orally once daily 2, 4
- Timing: Same fasting requirements as adults—at least 1 hour before or 2 hours after food 1
- Pharmacokinetic rationale: The 10 mg pediatric dose produces similar plasma exposure (AUC and Cmax) to the 20 mg adult dose, with median pediatric/adult ratios of 0.93 and 0.91 respectively 4
Critical Administration Instructions
Food and Beverage Interactions
The most important pitfall to avoid is taking bilastine with food or fruit juice, as this significantly impairs absorption. 1 The drug must be taken in a fasting state to achieve therapeutic plasma concentrations. Taking bilastine with meals slows and reduces absorption, potentially compromising efficacy 1.
Timing Strategy
- Administer bilastine either in the morning before breakfast (waiting 1 hour before eating) or at bedtime (at least 2 hours after the last meal) 1
- This fasting requirement distinguishes bilastine from many other antihistamines that can be taken with food 1
Special Populations
Renal Impairment
No dose adjustment is required for any degree of renal impairment, including severe renal insufficiency. 2, 5 Although bilastine exposure increases with declining renal function (AUC increases from 737.4 ng·h/mL in healthy subjects to 1708.5 ng·h/mL in severely impaired subjects), the drug remains well within safety margins even at these elevated levels 5. Renal excretion is the primary elimination route, with approximately 95% of the drug excreted unchanged 5.
Hepatic Impairment
No dose adjustment is required in hepatic impairment. 2 Bilastine undergoes minimal hepatic metabolism and does not interact with the CYP450 system, eliminating concerns about altered drug clearance in liver disease 2, 3.
Elderly Patients
No dose adjustment is required in elderly patients. 2 The lack of significant metabolism and absence of CYP450 interactions make bilastine particularly suitable for older adults who often take multiple medications 2.
Clinical Pharmacology Supporting Dosing
Onset and Duration
- Rapid onset of action with therapeutic effects beginning within hours of administration 2
- Long duration of action supporting once-daily dosing 2
- Elimination half-life: Approximately 14 hours 3
Drug Interaction Profile
Bilastine has minimal potential for drug-drug interactions because it does not undergo significant metabolism and does not interact with CYP450 enzymes 2, 3. This allows the standard dose to be maintained even in patients taking multiple medications 2.
Central Nervous System Effects
Bilastine shows no central nervous system penetration and has minimal sedative properties, allowing the full therapeutic dose to be used without concerns about drowsiness or impaired alertness 2, 3. The drug does not exhibit anticholinergic or cardiotoxic effects at standard doses 3.
Common Pitfalls to Avoid
- Taking with food or beverages: This is the single most important error to avoid, as it significantly reduces drug absorption 1
- Assuming dose adjustments are needed in renal/hepatic disease: Unlike many medications, bilastine requires no adjustment despite altered organ function 2, 5
- Splitting or crushing tablets: Administer as whole tablets to maintain proper pharmacokinetics 2
- Underdosing children based on weight alone: The 10 mg dose is appropriate for all children 6–11 years weighing ≥20 kg, not requiring further weight-based titration 2, 4