| Echinococcus granulosus, also known as hydatid disease or cystic echinococcosis, is caused by the larvae of Echinococcus granulosus. It is a serious zoonotic parasitic disease. And it's a common disease in livestock areas, widely distributed at almost every continent around the world. In China, Echinococcosis is distributed in 367 counties (cities) of 11 provinces, such as Xinjiang, Ningxia, Gansu, Qinghai, Tibet, Sichuan, Yunnan, Shaanxi, Shanxi and Henan. Cases of primary hydatid disease have been reported in Heilongjiang, Hebei, Tianjin, Anhui, Shandong, Hunan, Guizhou, etc. In addition, pathological reports of chinococciasis were also announced in Guangxi, Jilin, Jiangsu, Jiangxi, Shanghai, Fujian and other places but the origin of infection was unknown.Alveolar hydatid disease or multilocular hydatid diseases is caused by the larvae of Echinococcus multilocularis which mainly infected the liver but may also infect lung, brain and other organs sporadically. Alveolar hydatid disease is more harmful to human and called "cancer parasites" with a high mortality like cancer. In China, the epidemic area of alveolar hydatid disease is normally limited in mountainous or piedmont areas around 2000m above sea level in Ningxia, Gansu, Xinjiang, Qinghai and Sichuan provinces. Most of the patients had the history of hunting.Mebendazole is one of the two drugs recommended by WHO for treatment of hydatid disease. Among the existing clinical drugs for treatments of hydatidosis, mebendazole has the most significant effect on germinal layer of Echinococcus granulosus and the best efficacy on infected mice in the lab. However, due to its low solubility and poor absorbtivity, mebendazole is difficult to achieve the effective blood drug concentration range and the therapeutic effect is restricted. In clinical studies, the cure rate of mebendazole is only about 30%, and patient outcomes have large individual differences. Therefore, it is possible to change the formulation of mebendazole to promote drug absorption thereby increase plasma concentration and achieve the ultimate purpose of improving drug curative effect.Considering the situation that most of the patients come from poor areas, the simplicity and low-cost for the treatment should be mainly concerned in this study. In this study, the soft capsules of mebendazole are prepared and the contents of them are made into mebendazole-oleic acid suspension. The composition of the formulations is relatively simple. The pharmacokinetic study on the suspension shows that the relative bioavailability (F) and Cmax were increased significantly. And the pharmacodynamic study suggested that the cyst weight inhibition rate reached 82.04% when given at a single daily dose of 12.5mg/kg for 7 days. The oleic acid suspension was processed into soft capsule and the quality test results met the pharmacopoeia requirements.1. Studies on contents of Meb soft capsuleAssay method for concentration of mebendazole in oily suspension by HPLC was developed. The equilibrium solubility was determined when dispersing Meb in a variety of oil phase solvent. Oleic acid which had the highest solubility to mebendazole(C=329.43±9.70μg/ml) was selected as oil phase of the oily suspension. Beeswax and peanut oil were initially set as suspending agent and span80 as wetting agent when sedimentation volume ratio is taken as an index of performance assessment for stability. Accordingly,9 formulas were identified by orthogonal forms, which prepare well for the studies on drug bioavailability and other pharmacokinetic parameters.2. Pharmacokinetics of mebendazole Oleic acid suspension in miceMethod for determining Mebendazole plasma concentration was established. Mice were divided into 9 groups and given 9 formulas respectively. The plasma of mice was collected and measured individually at different time. According to the plasma concentration-time curve, the pharmacokinetic parameters were calculated with statistical moment by DAS software.. Overall, the relative bioavailability (F) and maximum plasma concentration (Cmax) were higher than in the control group which is intragastric administered with Meb dispersing in 1% gum tragacanth. Two prescriptions were selected from the nine in which formula 1 has a highest bioavailability (F=3.278) and formula 2 has a highest maximum plasma concentration (Cmax=4.232±0.384mg/L).3. Efficacy of Mebendazole soft capsule against Echinococcus granulosusThe KM mice were infected with Echinococcus granulosus for the efficacy study. The mice infected for 9 months were given ig at a single dose of 50mg/kg daily for 7 days then autopsied 1 month after drug withdraw. The cyst weight inhibitory rate was 80.64%. Then the further experiments were carried on by reducing the dose and infection time. When formula 1 was given at the daily doses of 25mg/kg and 12.5mg/kg to mice infected for 6 months, the cyst weight inhibitory rates were 92.8% and 82.04%respectively. When formula 2 was given at the daily doses of 25mg/kg and 12.5mg/kg to mice infected for 6 months, the cyst weight inhibitory rates were 92.05% and 81.07% respectively. The results of two formulas were significantly higher than the positive control group where the cyst weight inhibition rates were 26.1% and 15.0%. Taking into account the result that there was no significant difference between formula 1 and 2, formula 1 was more simple for preparation and the physical status of mice given formula 1 was better than 2, this study chooses formula 1 as the suspension contents of soft capsule.4. Studies on the shell of Mebendazole soft capsuleAccording to the contents of soft capsules, the compatibility of capsule shell material with contents was studied and the materials as well as their composition were determined. The soft capsule shell mainly consisting of gelatin, glycerin and water was produced by soft capsule machine. The appearance of mebendazole soft capsule is white and the content is white suspension at the room temperature. Disintegration time was less than 10min. The dissolution rate of 3 batches of samples is higher than 75% during 45min. Drug content of each capsule is 34.7±0.9 mg. All the quality test results meet the pharmacopoeia requirements. |
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