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Purpose: To investigate the effect of mebendazole on an in vivo solid tumor model of fibrosarcoma in hamsters.Methods: 24 Syrian golden hamsters of both sexes with the approximate body weight of 100g were randomly distributed in 2 experimental and 2 control groups, with 6 animals in each group. BHK-21/C13 cells (2 x 106) in 1 mL Glasgow Minimum Essential Medium (GMEM) were injected subcutaneously into the back of each animal in 3 groups. The experimental groups were treated with mebendazole (460 mg/kg) via a gastric tube on a daily basis, immediately after tumor inoculation. In addition, one experimental group received deoxycholic acid 20 mg/kg once a day. After 2 weeks, when the tumors were approximately 1 - 2 cm in the control group, all the animals were sacrificed, and their blood collected for laboratory analysis. The tumors were excised, their weight and diameters measured, and the volumes calculated. The tumor samples were histopathologically assessed and the main organs toxicologically analyzed. Images were taken and processed by an imaging software, and Ki-67-positive cells in the tumor samples were quantified.Results: Mebendazole diminished tumor mitosis from 18.5 ± 3.02 to 13.5 ± 3.45 (p < 0.05), vasculature and tissue penetration, and increased necroses in tumor slices. Tumor volume and weight were insignificantly attenuated. Toxicity was not observed.Conclusion: Mebendazole might be an effective non-toxic agent in sarcoma therapy.Keywords: Mebendazole, Hamsters, BHK-21/C13 cells, Fibrosarcoma therapy, Tumor mitosis

Although clinical trials have not been completed, it has already been confirmed that mebendazole, a well-known anti-parasitic drug widely used in the tropical areas, inhibits cancer cell growth. Preclinical studies show that mebendazole notably impedes the growth of malignant and metastatic tumors such as osteosarcoma and soft tissue sarcoma, melanoma, carcinoma (lung, colorectal, breast, ovarian, hepatocellular and adrenocortical), acute myeloid leukaemia, glioblastoma multiforme and meduloblastoma. Mebendazole can induce the depolymerization of microtubules in neoplasms and newly formed vasculature, stopping tumor growth and neoangiogenesis, along with other proposed mechanisms of action.Keywords: Anthelmintic, Mebendazole, Cancer treatment, Antimicrotubullar effect, Antineoangiogenesis

Purpose : To evaluate the predictive performance of phenytoin multiple dosing non-linear pharmacokinetic model in rabbits for possible application in therapy individualization in humans. Methods : Phenytoin was intravenously administered to 10 rabbits (2 – 3 kg). Plasma concentrations were measured by high pressure liquid chromatography (HPLC). Rabbits received 3 single phenytoin doses (11, 22 and 44 mg/kg) and plasma concentrations were fitted according to linear twocompartmental model. In all the rabbits, based on 3 different multiple doses (D1, D2, D3, range 9 – 15 mg/kg), 3 steady state plasma concentrations (Css1, Css2, Css3, range 20 - 56mg/l) were achieved. For multiple dosage, the non-linear parameters, Km and Vm, were calculated according to the equations: Km = (D1-D2)/[(D2/Css2)-(D1/Css1)] and Vm = D2+KmD2/Css2, and individually used to calculate Css3 = D3Km/(Vm-D3). Predicted and measured Css3 values were compared. Results : The values for pharmacokinetic parameters after single doses were dose-dependent. The pronounced inter-individual variations in Km (extreme values 18 – 91 mg/l differed 5.5 times) and Vm (11 – 28 mg/kg/h) values were recorded. Significant correlation of predicted Css3 with the measured value for the same dose (D3) was found (r = 0.854, N = 10, p < 0.01). There was no statistical difference between predicted and measured concentrations (t-dependent test = 1.074, p < 0.05). Conclusion : Non-linear parameters, Km and Vm, obtained from only two steady-state concentration measurements can be successfully used to compute and achieve a particular steady-state plasma concentration and optimal dosage regimen. Keywords : Phenytoin, Rabbit, Pharmacokinetic model, Multiple dosing, Non-linear, Individualization