Loratadine is an antihistamine of the 2nd generation which is produced by pharmaceutical industry of Ukraine. As a part of the development of hygienic standard of acceptable content in the working area of loratadine and definition of indicators, which may be used for the diagnosis of hidden intoxication among workers in manufacturing, immunotoxic effect of the drug was studied on laboratory animals.

Experiments have been carried out on light-colored guinea pigs, weighing 300–350 g. The animals were divided into two groups (control and experimental) for 8 animals in each group. Sensitization of guinea pigs was carried out by intradermal administration of 200 mg (0.02 ml) of the substance in the outer surface of ear. Control animals received physiological saline in the same volume. The degree of sensitization was adjusted after setting intracutaneous tests in dilutions: 1:100, 1:1000, 1:10,000.

The reaction of the organism was estimated by visual inspection of the skin surface at the site of tests in 20–30 minutes, 4–5 hours and 24 hours.

Clinical and immunological tests were performed after 24 hours. Changes in indicators of peripheral blood (white blood cells, basophils, eosinophils, neutrophils, monocytes) were studied. The state of immunological reactivity on the content of T-lymphocytes and B-lymphocytes was investigated: CD3 (T lymphocytes), CD4 (helper T cells), CD8 (cytotoxic T), SD16 (natural killer cells – NK), SD22 (B-lymphocytes). In order to assess the state of nonspecific resistance of the organism, the phagocytic activity of the blood of guinea pigs was determined, that was sensitized with loratadine and phagocytic index. Humoral immunity was studied by changing the concentration of immunoglobulins A, M, G, and the level of circulating immune complexes. Immunoregulatory (SD4/SD8), hematologic (ratio of lymphocytes and monocytes, neutrophils and monocytes, neutrophils and eosinophils) and immunological (leuco – T-cell, white blood B-cell) indexes wewe calculated.

It was found that after intracutaneous tests changes in the skin of guinea pigs were absent. Values percentage and absolute amount of leukocytes and their populations, as well as hematological indices in the treated and control animal groups were not significantly different.

Shifts in immunograms were characterized by a slight increase in the amount of NK cells (SD16) in absolute numbers and in percentage compared to the control group of animals, but did not have a reliable character, that was confirmed by calculation of index numbers of immune status.

Phagocytic activity of blood neutrophils in guinea pigs, sensitized by loratadine has not changed. Phagocytic index was at the level of the control group.

At a part of humoral immunity a significant increase in circulating immune complexes in the treated group was recorded, which did not exceed the fluctuation of the physiological norm. Concentrations of serum immunoglobulin A, M, G were not significantly different from control.

The results allowed to conclude that loratadine at intradermal sensitization in guinea pigs does not cause significant changes in the peripheral blood of animals, does not affect the cellular and humoral innate and adaptive immunity.

Keywords: loratadine, immunotoxicity, cell-mediated and humoral immunity

Full text: PDF (Ukr)