Levocetirizine exhibited linear pharmacokinetics over the
therapeutic dose range in adult healthy subjects.
Levocetirizine is rapidly and extensively absorbed following oral
administration. In adults, peak plasma concentrations are achieved 0.9 hour
after administration of the oral tablet. The accumulation ratio following daily
oral administration is 1.12 with steady state achieved after 2 days. Peak
concentrations are typically 270 ng/mL and 308 ng/mL following a single and a
repeated 5 mg once daily dose, respectively. Food had no effect on the extent of
exposure (AUC) of the levocetirizine tablet, but Tmax was
delayed by about 1.25 hours and Cmax was decreased by
about 36% after administration with a high fat meal; therefore, levocetirizine
can be administered with or without food.
A dose of 5 mg (10 mL) of levocetirizine dihydrochloride oral solution is
bioequivalent to a 5 mg dose of levocetirizine dihydrochloride tablets.
Following oral administration of a 5 mg dose of levocetirizine dihydrochloride
oral solution to healthy adult subjects, the mean peak plasma concentrations
were achieved approximately 0.5 hour post-dose.
The mean plasma protein binding of levocetirizine in vitro ranged from 91 to 92%, independent of
concentration in the range of 90-5000 ng/mL, which includes the therapeutic
plasma levels observed. Following oral dosing, the average apparent volume of
distribution is approximately 0.4 L/kg, representative of distribution in total
body water.
The extent of metabolism of levocetirizine in humans is less than
14% of the dose and therefore differences resulting from genetic polymorphism or
concomitant intake of hepatic drug metabolizing enzyme inhibitors are expected
to be negligible. Metabolic pathways include aromatic oxidation, N- and
O-dealkylation, and taurine conjugation. Dealkylation pathways are primarily
mediated by CYP 3A4 while aromatic oxidation involves multiple and/or
unidentified CYP isoforms.
The plasma half-life in adult healthy subjects was about 8 to 9
hours after administration of oral tablets and oral solution, and the mean oral
total body clearance for levocetirizine was approximately 0.63 mL/kg/min. The
major route of excretion of levocetirizine and its metabolites is via urine,
accounting for a mean of 85.4% of the dose. Excretion via feces accounts for
only 12.9% of the dose. Levocetirizine is excreted both by glomerular filtration
and active tubular secretion. Renal clearance of levocetirizine correlates with
that of creatinine clearance. In patients with renal impairment the clearance of
levocetirizine is reduced [see Dosage and
Administration (2.3)].
In vitro data on metabolite
interaction indicate that levocetirizine is unlikely to produce, or be subject
to metabolic interactions. Levocetirizine at concentrations well above Cmax level achieved within the therapeutic dose ranges is not an
inhibitor of CYP isoenzymes 1A2, 2C9, 2C19, 2A1, 2D6, 2E1, and 3A4, and is not
an inducer of UGT1A or CYP isoenzymes 1A2, 2C9 and 3A4.
No formal in vivo drug interaction studies have
been performed with levocetirizine. Studies have been performed with the racemic
cetirizine [see Drug Interactions
(7)].
Data from a pediatric pharmacokinetic study with oral
administration of a single dose of 5 mg levocetirizine in 14 children age 6 to
11 years with body weight ranging between 20 and 40 kg show that Cmax and AUC values are about 2-fold greater than that reported
in healthy adult subjects in a cross-study comparison. The mean Cmax was 450 ng/mL, occurring at a mean time of 1.2 hours,
weight-normalized, total body clearance was 30% greater, and the elimination
half-life 24% shorter in this pediatric population than in adults.
Pharmacokinetic information in pediatric patients (age 1
to 5 years) is approved for UCB Inc.'s levocetirizine dihydrochloride drug
product. However, due to UCB Inc.'s marketing exclusivity rights; this drug
product is not labeled for such use in pediatric patients.
Limited pharmacokinetic data are available in elderly subjects.
Following once daily repeat oral administration of 30 mg levocetirizine for 6
days in 9 elderly subjects (65–74 years of age), the total body clearance was
approximately 33% lower compared to that in younger adults. The disposition of
racemic cetirizine has been shown to be dependent on renal function rather than
on age. This finding would also be applicable for levocetirizine, as
levocetirizine and cetirizine are both predominantly excreted in urine.
Therefore, the levocetirizine dihydrochloride tablets dose should be adjusted in
accordance with renal function in elderly patients [see Dosage and Administration (2)].
Pharmacokinetic results for 77 patients (40 men, 37 women) were
evaluated for potential effect of gender. The half-life was slightly shorter in
women (7.08 ± 1.72 hr) than in men (8.62 ± 1.84 hr); however, the body
weight-adjusted oral clearance in women (0.67 ± 0.16 mL/min/kg) appears to be
comparable to that in men (0.59 ± 0.12 mL/min/kg). The same daily doses and
dosing intervals are applicable for men and women with normal renal
function.
The effect of race on levocetirizine has not been studied. As
levocetirizine is primarily renally excreted, and there are no important racial
differences in creatinine clearance, pharmacokinetic characteristics of
levocetirizine are not expected to be different across races. No race-related
differences in the kinetics of racemic cetirizine have been observed.
Levocetirizine exposure (AUC) exhibited 1.8-, 3.2-, 4.3-, and 5.7-fold increase in mild,
moderate, severe, renal impaired, and end-stage renal disease patients,
respectively, compared to healthy subjects. The corresponding increases of
half-life estimates were 1.4-, 2.0-, 2.9-, and 4-fold, respectively.
The total body clearance of levocetirizine after oral dosing was correlated
to the creatinine clearance and was progressively reduced based on severity of
renal impairment. Therefore, it is recommended to adjust the dose and dosing
intervals of levocetirizine based on creatinine clearance in patients with mild,
moderate, or severe renal impairment. In end-stage renal disease patients
(CLCR < 10 mL/min) levocetirizine is contraindicated.
The amount of levocetirizine removed during a standard 4-hour hemodialysis
procedure was <10%.
The dosage of levocetirizine dihydrochloride tablets should be reduced in
patients with mild renal impairment. Both the dosage and frequency of
administration should be reduced in patients with moderate or severe renal
impairment [see Dosage and Administration
(2.4)].
Levocetirizine dihydrochloride tablets have not been studied in
patients with hepatic impairment. The non-renal clearance (indicative of hepatic
contribution) was found to constitute about 28% of the total body clearance in
healthy adult subjects after oral administration.
As levocetirizine is mainly excreted unchanged by the kidney, it is unlikely
that the clearance of levocetirizine is significantly decreased in patients with
solely hepatic impairment [see Dosage and
Administration (2)].