ABSTRACT
In this paper, a new type of preparation for treatment of initial dry eye disease, thermosensitive in situ gel, was prepared using levocarnitine as a model drug. Poloxamer 407 and poloxamer 188 were used as the gel matrix, and sodium hyaluronate and sodium carboxymethylcellulose were used as bioadhesive materials. Gelation temperature was determined by a rotor method and the prescription was optimized by central composite design-response surface methodology. The pH value, viscosity value and gelation temperature of the optimal prescription were measured. The release of the drug in vitro was examined by dialysis membrane permeation, and retention time of the thermosensitive in situ gel preparation on the rabbit's ocular surface was observed by a slit lamp microscope. The results showed that the dosage of the poloxamer 407 and poloxamer 188 were 20.81% and 3.46%, respectively, and sodium hyaluronate was 0.02%, sodium carboxymethyl cellulose was 0.10% of the optimal formulation of levocarnitine thermosensitive in situ gel. The pH value was 6.90 ± 0.06 at room temperature and the viscosity value started to rise sharply at 27 ℃ of the optimal formulation. The gelation temperature of the optimal preparation before and after dilution by simulated tear fluid were (26.37 ± 0.06) ℃ and (33.57 ± 0.21) ℃, respectively. In the first 240 min, in vitro release rate per unit area of levocarnitine thermosensitive in situ gel was lower than that of solution (P<0.05), and after 600 min, the cumulative release rate of levocarnitine thermosensitive in situ gel could reach more than 80%. The retention time of the thermosensitive in situ gel preparation on rabbit's ocular surface reached about 25 min, at least 5 times as much as that of the solution. The animal experiment was conducted following the National Institutes of Health Guidelines for the use of experimental animals, and approved by the Ethics Committee of the Experimental Animal Center of Beijing University of Chinese Medicine. The levocarnitine thermosensitive in situ gel showed good characteristics and sustained release property and significantly improved the retention time of the drug on the rabbit's ocular surface.
ABSTRACT
Classical prescriptions are precious wealth left by ancient Chinese medical scientists. Moreover,they are also the important part of the treasure-house in Chinese medicine. Classical prescriptions have a long and rich history for human-use in China and play an important role in keeping people healthy. The state administration of traditional medicine of China published the Catalogue of Classical Prescriptions(first batch) in 2018. This measure has inspired the enthusiasm of Chinese medicine manufacturers to study ancient classical prescriptions and develop classical compound prescriptions. Based on the first batch of classical prescriptions, the dosage forms, sources, prescription components, decocting degree, use of toxic drugs and processing methods of classical prescriptions. The results showed that most of the classical prescriptions in the first batch were decoction and boiled powder,while only four of them were powder and paste forms,all of which were originated from representative classics in the past dynasties. The dosage and decocting degree of decoction were greater than those of boiled powder. The dosage and decocting degree of decoction in Han and Tang Dynasties was close to that in Ming and Qing Dynasties,higher than that in Song and Jin Dynasties. Moreover,the average number of herbs in the prescriptions in Han Dynasty was the smallest. The use of toxic traditional Chinese medicine was the most frequent in Han Dynasty, and Pinellia ternata was the most common toxic medicine. There were various processing methods, including cleansing, cutting, stir-frying, roasting and so on. In this paper, the dosage forms of traditional paste, the time concept of decoction in the ancient times, the traditional roasting method and the processing method of toxic drugs were summarized to provide ideas and reference for further development of classical prescriptions.