| Objective: Berberine(BER)existes in the form of quaternary ammonium salt. Its hydrochlorate,hydroiodic,sulfate and nitrate are all indissolvable, and its hydrochlorate is frequently used clinically. As a drug of heat-clearing, detoxicating and antimicrobial, BER inhibits and kills varied Gram-positive bacteria, Gram-negative bacteria, tubercule bacillus and fungus. However, BER has bad absorbability and poor bioavailability, which has certain influence to activity.Niosome(sVES), a system of microparticle drug-loaded, has the extremely similar membrane structure with cellular membrane, which will increase the uptake of the drug loaded in it, raise drug bioavailability, change drug distribution and degrade drug toxicity. This experiment will study the preparation of BER niosomes(BN)and investigate its pharmacokinetics in vivo, with the aim to find out a new dosage form of BER.Method: Determine the dissolubility of BER in buffer solution with different pH, and the n-octanol/buffer partition coefficient by the mothed of balance-dissolubility. The factors influenced encapsulating rate of BN were investigated, such as the kinds of surfactants, the ratio of surfactant toβ-sitosterol, hatching time, hatching tempareture, concentration of BER, pH of buffer solution, and so on. Ignoring the uninfluenced or less influenced ones, we has used the orthogonal design for the factors that have more influence. These factors were the ratio of span 20 toβ-sitosterol, the concentration of BER solution, the pH of buffer solution. The orthogonal experiment was progressed and the optimized formulation was got. Then, we observed the appearance of BN by light microscope, computed its particle diameter by Motic Images Advanced 3.2 system, and drew particle diameter distribution curve. The encapsulating rate of BN was determined by HPLC.Compared with the BER suspension, the releasing rate of BN in artificial gastric juice and artificial intestinal juice was investigated, and the disslution curve was drew.12 rats were divided into two groups randomly and injected BN and BER suspension, respectively(s.c). At specified time, we collected 1 ml of blood from rats orbit, and determined BER concentration in surem by HPLC. The data was dealed with by 3p97, and the pharmacokinetics parameters were carried out. Another 10 rats were divided into two groups randomly, and injected BN and BER suspension, respectively(s.c). After 90 min, we executed them, selected the tissue of heart, liver, spleen, lungs, kidney, brain and fat, prepared 25%(m/v)tissue homogenate, and determined drug concentration in these tissues by HPLC.BN was laid in different temperature for 24h to study the influence of temperature to encapsulating rate, and laid in common temperature for a few days to study its stability.Result: The dissolubility of BER rised as the pH of buffer rised, and when pH was 12, the dissolubility of BER was biggest, up to 1.807 mg·ml-1. When pH was 13, the distribution coefficient is 48.97, which was the biggest. The optimized formulation of BN was as follow: the ratio of span 20 toβ-sitosterol is 200:15; the pH of buffer solution is 10; the concentration of ber solution is 0.5 mg·ml-1. The VES was in the shape of cycle, and the particle diameter was 300~800nm. The encapsulating rate by HPLC was 31.73%.BN had the same releasing rate with BER suspension in the artificial gastric juice, with the cumulative release percentage 80% within 2h, while had lower releasing rate than BER suspension in the artificial intestinal juice, with the cumulative release percentage 50% within 2h, which illustrated that BN will slow-release in artificial intestinal juice.BN could significantly increase the absorption of BER, and there wasn't absorption phase in the drug concentration -time curve. The concentration of BER was up to 0.53μg·ml-1 120 min later, which was the second peak. When the rats were injected BER suspension, there was a peak concentration after 90min, 0.49μg·ml-1. After 1440min, there was little of BER in the rats injected of BER suspension, while the drug concentration remained 0.05μg·ml-1 in the rats injected BN.The data was dealed with 3p97, and the pharmacokinetics modle of both two groups of rats was one-compartment model with the weight of 1. Compared with BER suspension, BN had a longer half life period(281.652min to 218.667min). The clearance rates of BN and BER suspension were 136ml·kg-1·min-1 and 211ml·kg-1·min-1, and the AUC0→t was 186.520 and 126.314(μg·ml-1)·min, respectively.Kidney was checked out to maintain the highest concentration of BER after 90 min(30.669±18.682μg·g-1 in rats injected BN, and 19.387±8.105μg·g-1 in rats injected BER suspension), which was followed by heart and lungs. There was a little of BER in the brain, and the concentration was 0.552±0.157μg·g-1, 0.372±0.045μg·g-1 when injected BN and BER suspension, respectively.The encapsulating rate of BN didn't change after 24h when the temperature was lower than 40℃. In a contrary manner, when the temperature was higher than 40℃, the encapsulating rate decreased significantly. After 7d when laid in common temperature, the encapsulating rate was up to maximum, but 30d later, it decreased significantly.Conclusions: BN perepared by film dispersion method has a similar appearance and a high encapsulating rate. It can enhance the absorption of BER, increase the drug concentration in all the tissues, decrease clearance rate and raise drug bioavailability in vivo. But it has a bad stability in common temperature, so it must be dried for reservation.
|
PDF Full Text Request