CLARINEX-D 12 HOUR Extended Release Tablets (desloratadine/pseudoephedrine sulfate)(八)
one. Single daily doses of CLARINEX 45 mg were given to normal male and female volunteers for 10 days.
All ECGs obtained in this study were manually read in a blinded fashion by a cardiologist. In the CLARINEX-treated subjects, there was a mean increase in the maximum heart rate of 9.2 bpm relative to placebo. The QT interval was corrected for heart rate (QTc) by both Bazett's and Fridericia methods. Using the QTc (Bazett) there was a mean increase of 8.1 msec in the CLARINEX-treated subjects relative to placebo. Using QTc (Fridericia) there was a mean increase of 0.4 msec in CLARINEX-treated subjects relative to placebo. No clinically relevant adverse events were reported.
12.3 Pharmacokinetics
Absorption:
In a single dose pharmacokinetic study, the mean time to maximum plasma concentrations (Tmax) for desloratadine occurred at approximately 4 to 5 hours post dose and mean peak plasma concentrations (Cmax) and area under the concentration-time curve (AUC) of approximately 1.09 ng/mL and 31.6 ng∙hr/mL, respectively, were observed. In another pharmacokinetic study, food and grapefruit juice had no effect on the bioavailability (Cmax and AUC) of desloratadine.
For pseudoephedrine, the mean Tmax occurred at 6 to 7 hours post dose and mean peak plasma concentrations (Cmax) and area under the concentration-time curve (AUC) of approximately 263 ng/mL and 4588 ng∙hr/mL, respectively, were observed. Food had no effect on the bioavailability (Cmax and AUC) of pseudoephedrine.
Following oral administration of CLARINEX-D 12 HOUR Extended Release Tablets twice daily for 14 days in healthy volunteers, steady-state conditions were reached on Day 10 for desloratadine, 3-hydroxydesloratadine and pseudoephedrine. For desloratadine, mean steady-state peak plasma concentrations (Cmax) and area under the concentration-time curve (AUC 0–12 h) of approximately 1.7 ng/mL and 16 ng∙hr/mL were observed, respectively. For pseudoephedrine, mean steady state peak plasma concentrations (Cmax) and AUC (0–12 h) of 459 ng/mL and 4658 ng∙hr/mL were observed.
Distribution:
Desloratadine and 3-hydroxydesloratadine are approximately 82% to 87% and 85% to 89%, bound to plasma proteins, respectively. Protein binding of desloratadine and 3-hydroxydesloratadine was unaltered in subjects with impaired renal function.
Metabolism:
Desloratadine (a major metabolite of loratadine) is extensively metabolized to 3-hydroxydesloratadine, an active metabolite, which is subsequently glucuronidated. The enzyme(s) responsible for the formation of 3-hydroxydesloratadine have not been identified. Data from clinical trials with desloratadine indicate that a subset of the general population has a decreased ability to form 3-hydroxydesloratadine, and are poor metabolizers of desloratadine. In pharmacokinetic studies (n= 3748), approximately 6% of subjects were poor metabolizers of desloratadine (defined as a subject with an AUC ratio of 3-hydroxydesloratadine to desloratadine less than 0.1, or a subject with a desloratadine half-life exceeding 50 hours). These pharmacokinetic studies included subjects between the ages of 2 and 70 years, including 977 subjects aged 2 to 5 years, 1575 subjects aged 6 to 11 years, and 1196 subjects aged 12 to 70 years. There was no difference in the preva lence of poor metabolizers across age groups. The frequency of poor metabolizers was higher in Blacks (17%, n=988) as compared to Caucasians (2%, n=1462) an |
