Background: Allergic diseases are considered as the major burden on public health with increased prevalence
globally. Histamine H1-receptor antagonists are the foremost commonly used drugs in the treatment of allergic
disorders. The target drug in this study , loratadine, belongs to this class of drugs and its biometabolite desloratadine
which is also a non-sedating H1 receptor antagonist with anti-histaminic activity being 2.5 to 4 times greater than
loratadine. This study aimed to develop and validate a novel isocratic Reversed-phase High-Performance Liquid
Chromatography (RP-HPLC) method for rapid and simultaneous separation and determination of loratadine and its
metabolite, desloratadine in human plasma.
Methods: The drug extraction method from plasma was based on protein precipitation technique. The separation was
carried out on a Thermo Scientific BDS Hypersil C18 column (5μm, 250 x 4.60 mm) in a mobile phase of MeOH:
0.025M KH2PO4 adjusted to pH 3.50 using orthophosphoric acid (85: 15, v/v) at an ambient temperature. The flow
rate was maintained at 1 mL/min and maximum absorption was measured using the PDA detector at 248 nm.
Results: The retention times of loratadine and desloratadine in plasma samples were recorded to be 4.10 and 5.08
minutes, respectively, indicating a short analysis time. Limits of detection were found to be 1.80 and 1.97 ng/mL for
loratadine and desloratadine, respectively, showing a high degree of sensitivity of the method. The method was then
validated according to FDA guidelines for the determination of the two analytes in human plasma.
Conclusion: The results obtained indicate that the proposed method is rapid, sensitive in the nanogram range, accurate,
selective, robust and reproducible compared to other reported methods.