An HPLC-MS method has been developed and validated for the quantitative determination of milbemycin oxime (MBO) in dog plasma. The developed method has been then applied in in vivo clinical studies to obtain pharmacokinetics of MBO in blood after its oral administration. Samples were extracted using solid-phase extraction (SPE). Sample proteins were precipitated with acetonitrile (ACN) and sodium chloride (NaCl) and then diluted with methanol and water. Calibration standards were prepared by using plasma matrix and following the same SPE procedure. Chromatographic separation was performed on a Waters C₁₈ packed column (3.5 μm particles diameter; 3 × 100 mm) with a C₁₈ guard column (3.5 μm particles diameter; 3 × 20 mm). The mobile phase was an 85:15 (v/v) mixed solution of ACN and 5 mM ammonium acetate. The calibration curve was linear over a concentration range of 2.0–500 ng/mL with a limit of quantitation of 2.0 ng/mL. The oral administration of a pellet of 2.5 mg MBO produced blood concentrations ranging from 6.10 ± 0.92 to 78.81 ± 4.38 ng/mL within 6 h, with a terminal half-time of 11.66 ± 0.93 h. This study determined the suitability of the herein proposed method to investigate the pharmacokinetics of MBO after oral administration.

Objective: To evaluate the protective effects and potential mechanisms of Yang He decoction (YHD), a classic traditional Chinese medicine formula, against cyclophosphamide (CTX)-induced immunosuppression in mice. Methods: An immunosuppression model was established in Kunming mice via intraperitoneal injection of CTX (80 mg/kg). The mice were then treated with low, medium, or high doses of YHD (50, 100, or 200 mg/kg) or Astragalus polysaccharide (APS, 24 mg/kg) as a positive control for 15 consecutive day. Body weight changes, immune organ (spleen and thymus) index and histopathology, splenic lymphocyte proliferation and cell cycle distribution, and serum levels of cytokines (IL-1β, IFN-γ, TNF-α, IL-6, and IL-10) were systematically assessed. Results: YHD treatment significantly ameliorated CTX-induced immunosuppression. The medium dose (100 mg/kg) increased body weight by 58.5% (vs. 17.3% in the APS group), restored the spleen index to 9.41 ± 0.94 (0.52-fold vs. Model group 1.8 ± 0.3), and enhanced ConA-stimulated lymphocyte proliferation (27.03% ± 0.92% vs. Model group 10.60% ± 4.78%, P < 0.01). Cell cycle analysis revealed that the percentage of S-phase cells increased from 4.13% to 13.47% in the YHDH group. YHD also rebalanced cytokines: the concentration of IL-1β increased from 25.73 to 77.10 pg/mL, while IL-10 decreased from 222.83 to 20.77 pg/mL. Histopathology confirmed restoration of organ integrity without necrosis. Conclusion: The multiherbal formula YHD confers substantial protection against CTX-induced immunosuppression. Its mechanisms are associated with the restoration of immune organ integrity, promotion of lymphocyte activity, and rebalancing of the cytokine profile. These findings provide a pharmacological basis for the traditional use of YHD and support its potential as an adjuvant therapy for managing chemotherapy-related immunosuppression.

Traditional Chinese medicine (TCM) serves as a significant adjunct to chemical treatment for chronic diseases. For instance, the administration of Baitouweng decoction (BTWD) has proven effective in the treatment of ulcerative colitis. However, the limited understanding of its pharmacokinetics (PK) has impeded its widespread use. Chinese Bama miniature pigs possess anatomical and physiological similarities to the human body, making them a valuable model for investigating PK properties. Consequently, the identification of PK properties in Bama miniature pigs can provide valuable insights for guiding the clinical application of BTWD in humans. To facilitate this research, a rapid and sensitive UPLC-MS/MS method has been developed for the simultaneous quantification of eleven active ingredients of BTWD in plasma. Chromatographic separation was conducted using an Acquity UPLC HSS T3 C₁₈ column and a gradient mobile phase comprising acetonitrile and water (containing 0.1% acetic acid). The methodology was validated in accordance with the FDA Bioanalytical Method Validation Guidance for Industry. The lower limit of quantitation fell within the range of 0.60–2.01 ng/mL. Pharmacokinetic studies indicated that coptisine chloride, berberine, columbamine, phellodendrine, and obacunone exhibited low , while fraxetin, esculin, fraxin, and pulchinenoside were rapidly absorbed and eliminated from the plasma. These findings have implications for the development of effective components in BTWD and the adjustment of clinical dosage regimens.