acebo-controlled trials in patients with Chronic Idiopathic Urticaria, rupatadine was effective reducing the mean pruritus score from baseline over the 4 week treatment period (change vs baseline: rupatadine 57.5%, placebo 44.9%) and decreasing the mean number of wheals (54.3% vs 39.7%).
5.2 Pharmacokinetic properties
Absorption and bioavailability
Rupatadine is rapidly absorbed after oral administration, with a tmax of approximately 0.75 hours after intake. The mean Cmax was 2.6 ng/ml after a single oral dose of 10 mg and 4.6 ng/ml after a single oral dose of 20 mg. Pharmacokinetics of rupatadine was linear for a dose between 10 and 40 mg. After a dose of 10 mg once a day for 7 days, the mean Cmax was 3.8 ng/ml. The plasma concentration followed a bi-exponential drop-off with a mean elimination half-life of 5.9 hours. The binding-rate of rupatadine to plasma proteins was 98.5-99%.
As rupatadine has never been administered to humans by intravenous route, no data is available on its absolute bioavailability.
Effect of the intake of food
Intake of food increased the systemic exposure (AUC) to rupatadine by about 23%. The exposure to one of its active metabolites and to the main inactive metabolite was practically the same (reduction of about 5% and 3% respectively). The time taken to reach the maximum plasma concentration (tmax) of rupatadine was delayed by 1 hour. The maximum plasma concentration (Cmax) was not affected by food intake. These differences had no clinical significance.
Metabolism and elimination
In a study of excretion in humans (40 mg of 14C-rupatadine), 34.6% of the radioactivity administered was recovered in urine and 60.9% in faeces collected over 7 days. Rupatadine undergoes considerable pre-systemic metabolism when administered by oral route. The amounts of unaltered active substance found in urine and faeces were insignificant. This means that rupatadine is almost completely metabolised. In vitro metabolism studies in human liver microsomes indicate that rupatadine is mainly metabolised by the cytochrome P450 (CYP 3A4).
Specific patient groups
In a study on healthy volunteers to compare the results in young adults and elderly patients, the values for AUC and Cmax for rupatadine were higher in the elderly than in young adults. This is probably due to a decrease of the first-pass hepatic metabolism in the elderly. These differences were not observed in the metabolites analysed. The mean elimination half-life of rupatadine in elderly and young volunteers was 8.7 hours and 5.9 hours respectively. As these results for rupatadine and for its metabolites were not clinically significant, it was concluded that it is not necessary to make any adjustment when using a dose of 10 mg in the elderly.
5.3 Preclinical safety data
Preclinical data reveal no special hazard for humans based on conventional studies of pharmacology, repeated dose toxicity, genotoxicity, and carcinogenic potential.
More than 100 times the clinically recommended dose (10 mg) of rupatadine did neither extend the QTc or QRS interval nor produce arrhythmia in various species of animals such as rats, guinea pigs and dogs. Rupatadine and one of its main active metabolites in humans, 3-hydroxydesloratadine, did not affect the cardiac action potential in isolated dog Purkinje fibres at concentrations at least 2000 times greater than the Cmax reached after the administration of a dose of 10 mg in humans. In a study that eva luated the effect on cloned human HERG channel, rupatad |
