| Infantile hemangioma (IH) is one of the most common tumors in infants and the incidence is estimated at 4%-5%. It is explained by clinical pathology that IH is produced mainly due to the proliferation of newborn’s abnormal endothelial cells. In 2008, Leaute-Labreze described the use of oral propranolol hydrochloride (PRO) for IH. Other related reports found that PRO had the particularly significant effect in the treatments of severe IH and even the IH, which can threaten the patients’ lives, as a result it is expected to be the first-line drug for the treatment of IH.But it also exists some shortcomings to take PRO orally. At first, clinical drug doses of 0.5-3 mg/kg/day is divided into 2-3 times, while a piece of medicine contains 10 mg drug, which means the medicine should be taken by many times. Therefore, it is easy to cause differences of the dose. Secondly, PRO given orally shows significant first pass metabolism with 30% bioavailability and the half-life of 3-4 h. As a result, it is necessary to take medicine by many times, which can cause these adverse effects include lethargy, restlessness, difficulty breathing, cool clammy skin and decreased appetite. Besides, it is not convenient to take medicine by oral application because of small age. As a result it leads to a bad compliance. In order to overcome the defects, we adopt to change the route of administration to improve the therapeutic efficacy of drugs and reduce the side effects of drug as well as improve the patient’s compliance.In the present study, PE and CHOL were used as the carrier materials and PRO was taken as the model drug to be wrapped into liposomes which were prepared by thin-film dispersion method. Liposomes were used to mix with 2% carbopol 934 to form PRO liposomal gel for transdermal administration. The novel preparations can not only raise the content of the drug in the skin, which reduced the side effects of drugs on other organs but also increase patient’s compliance. The main methods and results were as follows.1. Preparation of PRO liposomes and physicochemical characteristics studyThe drug content of PRO was determined by high performance liquid chromatography (HPLC) method. PRO liposomes were prepared by the thin-film dispersion method. On the basis of optimization with single factors, the orthogonal design method was employed for further optimization by taking the entrapment efficiency as index. The physical and chemical properties of PRO were evaluated. The morphology was investigated by transmission electron microscope (TEM). The partical size and Zeta potential were conducted in means of dynamic light scattering. Entrapment efficiency and drug loading were measured by HPLC. The results showed that the HPLC method which was established for determining the PRO concentration was specificity, repeatability, sensitivity. The morphology of liposomes was spherical and there were no adherence with others. The mean partical size, polydispersity index and Zeta potential were (237.6±0.3) nm, (0.234±0.014) and (-26.82±0.38) mV. The mean entrapment efficiency and drug loading were (42.01±1.10%) and (12.60±0.33%).2. Preparation of PRO liposomal gel and characteristics studyThe PRO liposomal gel was immediately neutralized with triethanolamine until pH 7.0-8.0 after the liposomes and 2% carbopol were mixed well. The morphology of PRO liposomes was investigated after they were entrapped into gel by scanning electron microscope (SEM). The sample impress factor tests were performed under experiments of centrifugation, light and heat to find the main factors. Rheological experiments were conducted to investigate rheological properties of preparations. Results showed that the liposomes were scattered in the surface of the gel with morphology of spherical. The PRO liposomal gel was uniform and the content had no significant change when tested by experiments of centrifugation, light and heat. Rheological experiments showed that the preparation of liposomal gel had a good adhesion and the viscosity will have no obvious change when stored at low temperature with no light preservation.3. Skin irritation testSkin irritation test was conducted on the normal skin and damaged skin of New Zealand rabbits to test irritancy after the administration of PRO liposomal gel for once and more times. The results showed that the PRO liposome gel had no skin irritation, which improved the compliance of the patients.4. Permeation study in vitroFranz diffusion pool was used to study the permeation of PRO liposomal gel on excised skin and PRO gel was also tested as control. The results showed that the steady penetration rate of the PRO liposomal gel and the PRO gel were 7.43±0.12μg/(cm2·h) and 5.62±0.15μg/(cm2·h).5. Study in vivoThe drug content of PRO was determined by HPLC method. PRO liposomal gel was given on live mice to test drug concentration in skin and PRO gel was also tested as control. The results showed that the HPLC method which was established for determining the PRO concentration was specificity, repeatability, sensitivity. The PRO concentration in skin after the application of PRO liposomal gel was obviously high than the application of PRO gel and at 24 h the former was 2 time of the latter.6. Histopathology examinationsHistopathology examinations were conducted on the skins of mice after the local administration of PRO liposomal gel and PRO gel for 24 h to study the permeation mechanism of PRO liposome gel and physiological saline solution without drug was also administered topically as control. Results showed that the stratum corneum cells and acanthocyte in stratum spinosum were arranged tightly. After the use of PRO liposome gel and PRO gel, the stratum corneum cells and acanthocyte were arranged loosely and intercellular space become larger. The thickness of the stratum corneum was significantly weakened and the free fragments of the stratum corneum can be seen in the surrounding of skin after the application of PRO liposome gel.7. Pharmacokinetics and tissue distribution of PRO liposome gel in miceThe drug content of PRO in plasma and tissues was detected by HPLC method. PRO liposome gel was administered topically to explore pharmacokinetics and tissue distribution of drug in mice. PRO suspension was administered orally as control. The results showed that the HPLC method was specificity, repeatability, sensitivity, which can meet the requirements of the determination of biological samples. After the application of PRO liposome gel in plasma the Cmax was 0.41±0.04μg/mL, Tmax was 6.50h, AUC0-t was 1.72±0.17μg/h/mL, while cmax was 1.17±0.13μg/mL, Tmax was 1.25 h, AUC0-t was 2.67±0.23μg/h/mL after the oral application of PRO suspension, both of which showed that there were little PRO in the blood circulation. Besides, relative uptake efficiency (re) of drugs in heart, liver, spleen, lung, kidney and skin were 0.74,0.27,0.95,0.59,0.56 and 74.10 respectively, which showed that PRO liposome gel can significantly increase drug concentration in skin and reduce the drug concentration in heart, liver, spleen, lung, kidney after the topical application compared with oral application of PRO suspension.ConclusionIn this study, we successfully prepared PRO liposome gel, which can greatly raise the drug concentration in skin and reduce the side effects of drugs on other tissues as well as improve patients’ compliance. Thus, PRO liposome gel will be a promising transdermal delivery carrier of PRO for the treatment of HI in the future. |
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