Levocetirizine Tablets

Mechanism

The active component of Levocetirizine dihydrochloride, is the R enantiomer of cetirizine hydrochloride, a racemic compound with antihistaminic properties. It is an orally active and selective H1-receptor antagonist. Histamines act on H1 receptors, causing the symptoms commonly seen in allergic reactions. Its inhibits these H1 receptors.

Pharmacokinetics

• Absorption: Rapidly and extensively absorbed. T max is 0.9 h. C max is 270 and 308 ng/mL after single and repeated once-daily dosing, respectively. Steady state achieved after 2 days.
• Distribution: Plasma protein binding about 92%. Vd is approximately 0.4 L/kg.
• Metabolism: Metabolism is less than 14% and by aromatic oxidation, N- and Odealkylation, and taurine conjugation.
• Elimination: The t ½ is about 8 to 9 h. Elimination is 85.4% and 12.9% via urine and feces, respectively. Excreted both by glomerular filtration and active tubular transport.

Side Effects

• Drowsiness
• Fatigue
• Dry mouth
• Headache

Contraindication

• History of angioedema
• Pregnancy
• Hypersensitivity to ACE inhibitors
• Severe renal artery stenosis

Interaction

• CNS depressants (Alcohol, benzodiazepines, opioids)
• ↑ Sedation, impaired alertness, Other antihistamines (Cetirizine, diphenhydramine)
• Additive drowsiness, no added benefit, Theophylline (high dose)
• Slight ↑ levocetirizine exposure, Ritonavir (Antiviral)
• May ↑ plasma concentration, Renal clearance competition

Warning and Precautions

• Avoid concomitant use with alcohol or other CNS depressants as additive drowsiness may occu
• Dose adjustment is required in patients with moderate to severe renal impairment.
• Levocetirizine should not be used in children under 6 years in tablet form.
• Use with caution in elderly patients due to increased sensitivity to side effects.
• Consult doctor during pregnancy & lactation

Dosage

As directed by the Physician.