Microspheres sterilization

An example of such a product is Sterile Medroxyprogestrone Acetate Suspension used for its contraceptive property. Such an injection is designed to provide up to three months of contraceptive activity. Another such product is a depot injection of leuprolode acetate, an analogue of gonadatropin-releasing hormone (see Drug delivery systems). In this case, the product is a sterilized powder of microspheres to be suspended upon the addition of an appropriate diluent and intended for monthly injection. 

R. A., Comparative evaluation of the safety and contraceptive effectiveness of 65 mg and 100 mg of 90-day norethindrone microspheres for controlled release steroid contraception Phase II study, Fertil. Steril., 51. 803, 1989. 

An excellent carrier is needed to deliver a sufficient amount of prostaglandins to the diseased site. Liposomes have been studied for a long time as possible drug carriers. However, the clinical use of liposomes has delayed because of some difficulties in mass production, sterilization, stability and safety. Since 1980 we have attempted to use lipid microspheres (lipid emulsions) instead of liposomes as a better carrier for lipophilic drugs (7). 

A large amount of lipid microspheres has been used under the name of Intralipid for almost 50 years and we used only 1 mL of it for DDS. Therefore, there was no problem with regard to safety, stability, sterilization and mass production. 

Commercial kits contain the lyophilized, sterile components including preformed albumin microspheres in a multidose vial, sealed under a nitrogen atmosphere. Labeling with Tc eluate is carried out under aseptic conditions by injecting a volume of 2-10 ml of eluate corresponding to a Tc activity of maximal of 5.5 GBq (5-150 mCi). The reaction is allowed to proceed at room temperature for 15 min. " Tc-human albumin microspheres (HAM) is a sterile, pyrogen-free suspension suitable for intravenous injection. The pH of the injection solution is 4.0-9.0 (European Pharmacopeia). 

Still other ceramics are important in medicine. For example, they are used to febricate artificial bones and to crown damaged teeth. The feet that many ceramics can be easily sterilized and are chemically inert makes ceramic microspheres made of these materials useful as biosensors. Drugs and other chemicals can be carried within microsphere pores to desired sites in the body. SEE ALSO Glass Minerals Semiconductors Superconductors. 

This chapter gives an overview of parenteral dosage forms and the rational for their use. Parenterals are sterile preparations that are injected intravascularly, administered into body tissues or into visceral cavities. The parenteral route of administration is often chosen for active substances that are poorly absorbed via the oral route or when rapid systemic availability and effects are required, or both. An introduction to the formulation and preparation of parenteral dosage forms is provided. Parenteral medicines can be formulated as solutions, emulsions or suspensions. Products, such as implants and microspheres are only briefly discussed. Knowledge about these types of products is a prerogative for the sound education of patients and caregivers in using the products. 

The second type of Y carrier is resin-based microspheres with a diameter of 29-35 pm and are also infused via the appropriate hepatic artery branch to provide selective internal radiation (SIR). These SIR-Spheres (Sirtex, Medical Limited) have an average activity of 40 Bq per sphere and can be suspended in sterile water and contrast media to the desired total activity [8,9j. Since the radioactive element is the same as that on glass microspheres. 

C. Volland, M. Wolff and T. Kissel, "The influence of gamma-sterilization on captopril containing poly(DL-lactide-co-glycolide) microspheres ", J. Control Rel, 31,293-305(1992). 

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