The recent decades has witness a rapid development of research and production of pharmaceutical. The original dosage form can’t meet the demands of improved level of drug use. But the new dosage form can improve the effectiveness of the drug, prolonged the duration of drug, improve the selectivity of drugs on the site of action, thereby increasing the effectiveness and safety of drugs. So in the late 1980s, preparations research began to shift to new drug delivery systems. New formulations of drugs are described as follows:
1, Micro capsules: Micro capsules could reduce the chance of contact between drugs and the outside world, thus play a protective role for easily oxidized substances. At the same time, micro capsules could slow the release of drug and prolonging the time of drug efficacy.
2, Transdermal drug delivery system: This system is easy to be administered and would not be affected by gastrointestinal tract factors.
3, Films: Films are characterized for accuracy of drug content, good stability, lightweight, small size, convenience in application et al. It may be suitable for a variety of application route.
4, Liposomes: Liposomes are spherical, closed structures, composed of curved lipid bilayers, which enclose part of the surrounding solvent into their interior.