Bilastine

Bilastine is a Second generation antihistamines belonging to anti-histaminic class.

Bilastine is an antihistamine medication used to treat symptoms of allergies such as hay fever, hives, and itchy skin. It works by blocking the effects of histamine, a natural substance produced by the body that causes allergic symptoms.

Bilastine is Rapidly absorbed from the gastrointestinal tract with Bioavailability of Approx 61%; decreased with food with Plasma protein binding of 84-90%. And get Minimally metabolized and get excreted Via faeces (66.5% as unchanged drug); urine (28.3% as unchanged drug).

Tmax of Bilastine is approximately 1 to 1.5 hours after oral administration.

Cmax of Bilastine after a single oral dose 110 ng/mL.

Bilastine shows common side effects like Headache, Drowsiness, Nausea,Dry mouth, Fatigue, Dizziness, Difficulty sleeping (insomnia), Upset stomach, Diarrhea

Bilastine is available in tablets, and oral suspension.

Bilastine is available in India, Germany, Canada, France.

Histamine antagonist with selective peripheral H₁ receptor antagonist affinity and no affinity for muscarinic receptors.

Bilastine is available in the form of tablets, and suspension.

Oral: Administer with water 1 hour before or 2 hours after intake of food or fruit juices.

Bilastine is a selective histamine H1 receptor antagonist (Ki = 64nM) . During allergic response mast cells undergo degranulation which releases histamine and other subastances. By binding to and preventing activation of the H1 receptor, bilastine reduces the development of allergic symptoms due to the release of histamine from mast cells.

Bilastine is approved for use in the following clinical indications

Allergic rhinitis: Relief of symptoms associated with seasonal allergic rhinitis in patients ≥4 years of age and weighing ≥16 kg.

Chronic spontaneous urticaria: Symptomatic treatment of adults with chronic spontaneous urticaria (eg, pruritus, hives) in patients ≥4 years of age and weighing ≥16 kg.

Oral

• Allergic rhinitis

Adult: For symptomatic relief of allergic rhino-conjunctivitis (seasonal allergic rhinitis and perennial allergic rhinitis): As conventional tab: 20 mg once daily. Limit treatment to the period of exposure to allergens. Seasonal allergic rhinitis: Discontinue treatment after the symptoms have resolved, reinitiate treatment if symptoms reappear. Perennial allergic rhinitis: Treatment may be continued during allergen exposure periods.

Child: For symptomatic relief of allergic rhino-conjunctivitis (seasonal allergic rhinitis and perennial allergic rhinitis): 6-11 years weighing at least 20 kg: As orodispersible tab and oral solution: 10 mg once daily. ≥12 years Same as adult dose.

Oral

• Urticaria

Adult: As conventional tab: 20 mg once daily. Treatment duration may vary depending on the type, duration, and course of the complaints.

Child: 6-11 years weighing at least 20 kg: As orodispersible tab and oral solution: 10 mg once daily. ≥12 years Same as adult dose.

Bilastine is available in the dosage strength of

• 10 mg and 20 mg, 1 mg/ml.

Bilastine is available in the form of tablets and oral suspension.

• Dosage Adjustment for Pediatric Patients:

For Children below 12 years:

For symptomatic relief of allergic rhino-conjunctivitis (seasonal allergic rhinitis and perennial allergic rhinitis): 6-11 years weighing at least 20 kg: As orodispersible tab and oral solution: 10 mg once daily. ≥12 years Same as adult dose.

Seasonal allergic rhinitis: Children ≥12 years and Adolescents: Oral: Refer to adult dosing

Take after eating and with a full glass of water to decrease gastric upset.

Hypersensitivity to bilastine or any component of the formulation; history of QT prolongation and/or torsades de pointes, including congenital long QT syndromes.

Disease-related concerns:

QT interval prolongation: QTc interval prolongation has been reported with use; use is contraindicated in patients with a history of QT prolongation and/or Torsade de pointes, including congenital long QT syndromes. Use caution in patients with a history of cardiac arrhythmia, significant bradycardia, a family history of sudden cardiac death, electrolyte abnormalities (eg, hypokalemia, hypomagnesemia), or with concomitant use of other QTc-prolonging drugs.

Bilastine may cause liver problems, and using it with substantial quantities of ethanol may increase that risk.

Bilastine is present in breast milk.

Concentrations of Bilastine in breast milk increase with supplementation. When used as a dietary supplement, the recommended dietary allowance of Bilastine is increased in breastfeeding patients compared to non-breastfeeding patients. 

Oral formulations should be administered on an empty stomach with water (at least 1 hour before or 2 hours after meals, milk, or other dairy products). Maintain fluid intake to ensure adequate hydration and urinary output.

• Common Adverse effects:

Headache, Dizziness, Somnolence (drowsiness), Fatigue ,Dry mouth ,Nausea ,Abdominal pain

• Less Common Adverse effects:

Hypersensitivity reactions such as rash, itching, and hives Palpitations (fast or irregular heart rate) Elevated liver enzymes Muscle pain Joint pain Restlessness Sleep disorders such as insomnia or abnormal dreams Visual disturbances Urinary retention

• Rare Adverse effects

Adrenal suppression (with long-term use) Anaphylaxis (a severe and life-threatening allergic reaction) Cushing's syndrome (with long-term use) Decreased immune system function (with long-term use) Hyperglycemia (high blood sugar levels) Hypokalemia (low levels of potassium in the blood) Hypersensitivity reactions (such as rash or angioedema) Ocular toxicity (such as increased intraocular pressure, cataracts, or glaucoma with long-term use) Psychiatric effects (such as mood changes or suicidal thoughts)

• Ketoconazole and other strong CYP3A4 inhibitors: These medications may increase the levels of bilastine in the body, leading to an increased risk of side effects such as drowsiness or dizziness.
• Rifampicin and other strong CYP3A4 inducers: These medications may decrease the levels of bilastine in the body, reducing its effectiveness.
• Erythromycin and other moderate CYP3A4 inhibitors: These medications may increase the levels of bilastine in the body, leading to an increased risk of side effects.
• Grapefruit juice: Grapefruit juice contains compounds that inhibit CYP3A4, which may increase the levels of bilastine in the body.

The common side effects of Bilastine include the following :

Headache, Dizziness, Fatigue, Somnolence, Dry mouth, Nausea, Diarrhoea, abdominal pain.

The symptoms of bilastine overdose are not well documented as overdose cases are rare. However, it is generally recommended to follow the prescribed dose of bilastine, and in case of accidental overdose or intentional ingestion of a large amount of bilastine, seek immediate medical attention.

Pharmacodynamic

Bilastine is a second-generation antihistamine that selectively antagonizes the H1 histamine receptors in the body. Its pharmacodynamic effects are primarily mediated by its ability to block the binding of histamine to H1 receptors in various tissues, thereby preventing the release of inflammatory mediators that cause symptoms such as itching, sneezing, runny nose, and hives.

Pharmacokinetics

• Absorption: The process by which a drug enters the bloodstream from its site of administration. This can occur through various routes, such as oral, intravenous, topical, or inhalation.
• Distribution: The process by which a drug is transported throughout the body to its target site(s) of action. This involves the movement of the drug from the bloodstream into various tissues and organs.
• Metabolism: The process by which the body breaks down the drug into smaller molecules that can be eliminated. This usually occurs in the liver, where enzymes convert the drug into metabolites that can be excreted from the body.
• Excretion: The process by which the drug and its metabolites are eliminated from the body. This can occur through various routes, such as urine, feces, sweat, or breath.

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1364710/
2. https://reference.medscape.com/drug/colestid-Bilastine -342452
3. https://go.drugbank.com/drugs/DB00375
4. https://www.sciencedirect.com/topics/medicine-and-dentistry/Bilastine
5. https://europepmc.org/article/med/6988203