Drug Interaction Between Bilastine and Pregabalin
No clinically significant drug interactions are expected between bilastine and pregabalin, and these medications can be safely used together.
Pharmacokinetic Basis for Safety
The lack of interaction between these two medications is based on their distinct metabolic pathways:
Bilastine undergoes minimal hepatic metabolism, is not metabolized by the cytochrome P450 system, and is excreted virtually unchanged by the kidneys, making drug-drug interactions unlikely 1.
Pregabalin is not subject to hepatic metabolism, does not bind to plasma proteins, is excreted virtually unchanged (<2% metabolism) by the kidneys, and does not induce or inhibit liver enzymes such as the cytochrome P450 system 2.
Neither medication interacts with CYP450 enzymes, which eliminates the most common mechanism for drug-drug interactions between these agents 2, 1.
Central Nervous System Considerations
While no direct interaction exists, both medications can independently cause CNS effects:
Pregabalin commonly causes somnolence, dizziness, and sedation as dose-dependent adverse effects 3, 4.
Bilastine is classified as non-sedating, shows minimal CNS penetration due to P-glycoprotein substrate activity, has the lowest cerebral histamine H1-receptor occupancy among second-generation antihistamines, and does not impair cognitive or psychomotor performance 5.
The risk of additive sedation is minimal given bilastine's non-sedating profile, though patients should be monitored for CNS effects primarily attributable to pregabalin 1, 5.
Dosing Recommendations When Used Concomitantly
No dose adjustments are required for either medication when used together, as no pharmacokinetic interaction occurs 2, 1.
Standard dosing applies: bilastine 20 mg once daily in adults (10 mg in children 6-12 years) and pregabalin starting at 100-300 mg at bedtime, titrating to 900-3600 mg/day in divided doses 4, 1.
Renal function monitoring is important since both medications are renally excreted, and dose adjustments may be necessary in patients with renal insufficiency for both drugs independently 2, 1.
Special Population Considerations
In elderly patients, use lower starting doses and slower titration of pregabalin to minimize adverse effects, while bilastine requires no dosage adjustment 4, 1.
Pregabalin should be tapered gradually over at least 1 week when discontinuing to avoid withdrawal symptoms; this precaution is independent of bilastine use 4.