RESUMEN
Objective: Levocetirizine hydrochloride is the R-enantiomer of cetirizine, which is a new-generation histamine H1 receptor antagonist with high safety, selectivity, and affinity. As a high-efficiency non-sedating antihistamine, levocetirizine hydrochloride has been widely used in the clinical treatment of skin, respiratory, and eye allergies. However, the bioavailability of levocetirizine hydrochloride granules remains to be determined. The study examined the relative bioavailability of the test drug (levocetirizine hydrochloride granules (Kangzhitai®)) and determined whether Kangzhitai® was bioequivalent to the reference drug (levocetirizine (Xyzal®)) in healthy individuals. Methods: Twenty eligible healthy male subjects were randomly divided into two groups. Group one received 5 mg of Kangzhitai®, followed by a 10-day wash-out period and 5 mg of Xyzal® on day 11. Group two received the same doses but in a reverse sequence. The subjects fasted for 12 h, and blood samples were collected before (blank) and after administration. The plasma concentration of Kangzhitai® was determined by HPLC-MS-MS. Pharmacokinetic parameters were analyzed using DAS 2.0 software. Results: The main pharmacokinetic parameters Cmax, Tmax, T1/2, AUC0-48, and AUC0-∞ of the Xyzal® and Kangzhitai® groups were as follows: (218.4 ± 46.4) µg/L vs. (213.6 ± 39.3) µg/L, (0.73 ± 0.32)/h vs. (0.75±0.3)/h, (9.2 ± 2.0) h vs. (8.9 ± 2.7) h, (1594.0 ± 337.2) µg·h/L vs. (1652.6 ± 383.5) µg·h/L, and (1683.2 ± 338.5) µg·h/L vs. (1753.7 ± 445.4) µg·h/L. The two-one-sided t tests of Cmax, AUC0-48, and AUC0-∞ showed that th and t1 were both higher than one-sided t0.05. The 90% confidence intervals (CI) for AUC0-48 and AUC0-∞ of Kangzhitai® did not exceed 80%-125% of AUC0-48 and AUC0-∞ of Xyzal®. The 90% CI for the Cmax of Kangzhitai® did not exceed 70%-143% of the Cmax of Xyzal®. There was no significant difference in Tmax between the two drugs. The relative bioavailability (F, assessed by AUC0-48) of Kangzhitai® vs. Xyzal® was 104.4±18.5%. No adverse events occurred during the drug administration. Conclusion: The results indicated that there was no significant difference in absorption between Kangzhitai® and Xyzal®, which confirmed the bioequivalence of the two drugs.