Levocet-Natrapharm Mechanism of Action

Pharmacology: Pharmacokinetics: Absorption: Bioavailability: Rapidly and extensively absorbed following oral administration, with peak plasma concentration (C_max) usually attained in 0.9 hr.
Onset: Antihistaminic effects occur within 1 hr. Symptomatic improvement observed as early as 1 day after initiation of therapy for allergic rhinitis or chronic idiopathic urticaria.
Duration: Antihistaminic effects persist for at least 24 hrs.
Food: A high-fat meal reduces C_max by about 36% and delays time to peak plasma concentration (T_max) by about 1.25 hrs, but does not affect the area under the concentration-time curve (AUC).
Special Populations: In patients with renal impairment, AUC is increased by 1.8-, 3.2- or 4.3-fold in those with mild, moderate or severe impairment, respectively; AUC is increased by 5.7-fold in those with end-stage renal disease. In pediatric patients, C_max and AUC following administration of 5-mg dose is approximately twice than that in adults.
Distribution: Extent: Average apparent volume of distribution is 0.4 L/kg, which represents distribution in total body water. Expected to distribute into milk.
Plasma Protein-Binding: Approximately 91-92% (mainly albumin).
Elimination: Metabolism: Metabolized to a limited extent (<14% of dose) by aromatic oxidation, N-dealkylation, O-dealkylation and taurine conjugation.
Elimination Route: Excreted in urine (85.4%) (via glomerular filtration and active tubular secretion) and in feces (12.9%). Less than 10% of dose removed by standard 4-hr hemodialysis procedure.
Half-Life (t_½): Approximately 8 hrs.
Special Populations: In patients with renal impairment, t_½ is increased by 1.4-, 2- or 2.9-fold in those with mild, moderate or severe impairment, respectively; t_½ is increased by 4-fold in those with end-stage renal disease. Total body clearance also progressively decreases based on severity or renal impairment (see Renal Impairment under Dosage & Administration).
In pediatric patients receiving a single 5-mg dose, total body clearance was 30% greater and elimination t_½ is 24% shorter than those observed in adults. In geriatric patients receiving 30 mg once daily for 6 days, total body clearance was 30% lower than that observed in younger adults; however, levocetirizine disposition appears to be dependent on renal function rather than on age.