What are the potential side effects of bilastine (antihistamine) in patients with impaired renal (kidney) or hepatic (liver) function?

Bilastine Side Effects

Bilastine is generally well tolerated with a safety profile similar to placebo, showing minimal sedative effects, no cardiotoxicity, and no requirement for dose adjustment in patients with renal or hepatic impairment. 1, 2, 3

General Safety Profile

• Headache is the most frequently reported adverse effect during clinical use 4
• The overall adverse event profile is comparable to placebo across all Phase I, II, and III clinical trials 2
• Bilastine demonstrates no sedative side effects, no cardiotoxic effects, and no hepatic metabolism 2
• The drug shows no central nervous system penetration and has minimal sedative properties 5
• No anticholinergic effects have been observed 5

Safety in Renal Impairment

No dose adjustment is required for bilastine 20 mg daily in patients with any degree of renal insufficiency, including severe impairment. 1, 3

• Although exposure (AUC and Cmax) 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 subjects—the increased exposure remains well within safety margins 1
• Renal excretion is the main elimination route, with approximately 95% of the drug excreted unchanged within 72 hours 1
• The oral plasma clearance to renal clearance ratio remains approximately equal across different degrees of renal impairment, indicating no compensatory alternative elimination routes are activated 1
• Bilastine 20 mg was well-tolerated in all renal impairment groups despite increased systemic exposure 1

Safety in Hepatic Impairment

No dose adjustment is required in patients with hepatic impairment, as bilastine is not metabolized and is excreted largely unchanged. 3, 5

• Bilastine does not undergo significant metabolism in humans and does not interact with the cytochrome P450 system 2, 3
• Hepatic impairment is not expected to increase systemic exposure above the drug's safety margin 3
• This contrasts with other antihistamines that require caution or are contraindicated in liver disease 6

Cardiovascular Safety

• No cardiotoxic effects have been demonstrated in clinical trials or post-marketing experience 2, 4
• The therapeutic dose does not alter heart rate 4
• No QT prolongation or arrhythmias have been reported 2

Central Nervous System Effects

• Bilastine 20 mg does not increase alcohol effects on the CNS, unlike cetirizine 2
• It does not increase the CNS depressant effect of lorazepam 2
• Bilastine 20 mg performs similarly to placebo in driving tests, meeting current criteria for medications used in allergic conditions 2
• The distribution in the brain is undetectable 2

Drug Interaction Profile

Bilastine has very low potential for drug-drug interactions due to lack of CYP450 metabolism. 3, 5

• The drug does not interact with the cytochrome P450 system 2, 3
• No dosage adjustments are required when used with other medications metabolized by CYP450 5

Use at Higher Doses

• Bilastine is generally well tolerated even at supratherapeutic doses up to 80 mg once daily (fourfold higher than standard dosage) 3, 5
• The fourfold higher dose is specified as an acceptable second-line treatment option for urticaria in international guidelines 3

Special Populations

• No dosage adjustments are required in elderly patients 5
• Bilastine is approved for use in children aged 6 to <12 years at 10 mg once daily and in adolescents ≥12 years at 20 mg once daily 5

Important Administration Consideration

• Bilastine should not be administered at meal times to avoid interference with the absorption process 4