Small-volume injectable suspensions

Many drugs are administered as parenterals for speed of action because the patient is unable to take oral medication or because the drug is a macromolecule such as a protein that is unable to be orally absorbed intact due to stability and permeability issues. The U.S. Pharmacopoeia defines parenteral articles as preparations intended for injection through the skin or other external boundary tissue, rather than through the alimentary canal. They include intravenous, intramuscular, or subcutaneous injections. Intravenous injections are classified as small volume (<100 mL per container) or large volume (>100 mL per container) injections. The majority of parenteral dosage forms are supplied as ready-to-use solutions or reconstituted into solutions prior to administration. Suspension formulations may also be used,101 although their use is more limited to a subcutaneous (i.e., Novolin Penfill NOVO Nordisk) or intramuscular (i.e., Sandostatin LAR Depot Novartis) injection. Intravenous use of disperse systems is possible but limited (i.e., Doxil Injection Ortho Biotec). 

The soluble substances, mild irritants and suspensions can be injected by this route in the large skeletal muscles (deltoid, triceps, gluteus maximus, rectus femoris etc.). These muscles are less richly supplied with sensory nerves and are more vascular, so irritant solutions can be injected. Small volumes (up to 2 ml) are injected into the deltoid muscle, and small or large volumes (up to 10 ml) are injected into the gluteal mass. 

Small-Volume Parenterals Color, clarity of solutions, particulate matter, pH, sterility, endotoxins. Powders for injection solutions include clarity, color, reconstitution time and water content, pH, sterility, endotoxins/pyrogens, and particulate matter. Suspensions for injection should include additional particle size distribution, redispersability, and rheological properties. Emulsion for injection should include phase separation, viscosity, mean size, and distribution of dispersed globules. 

Subcutaneous injections are usually aqueous solutions or suspensions administered in small volumes of 2mL or less. They are generally given in the forearm, upper arm, thigh, or abdomen. The site should be rotated if frequent injections are to be given, to reduce tissue irritation. 

The widest range of parenteral products are however, the small volume parenterals (SVPs). These may be sterile solutions for injecting directly into the patient. They may be concentrated solutions or suspensions or emulsions or even solids (solid dosage forms may be anhydrous, crystalline, or freeze dried [lyophilized]) for dilution or reconstitution in LVPs for direct injection or infusion into the patient. 

Class 10,000 areas are suitable to prepare solutions that shall be sterile but cannot be sterilized in their final containers (referring to that sterile filtration is needed before filling) to prepare solutions of large volume parenterals that can be sterilized in their final containers to prepare, filter, fill and seal solutions of small volume parenterals fc50ml) and eye drops to prepare, filter, fill and seal oral solutions that can not be sterilized by steam sterilization to prepare, fill and seal ointments, creams, suspensions, emulsions that can not be sterilized in their final containers and to purify, dry, and package bulk pharmaceuticals for preparing injections. 

However, due to the small volume involved in such a configuration, the assembly process is very sensitive to the evolution of concentrations as evaporation goes on. One possible implementation of the technique may be to supply continuously the suspension via an injection line to the meniscus, keeping the volume fraction exactly constant. 

A 10 ml suspension of Cr -labeled red blood cells, containing 3x 10 CPM total radioactivity, was injected into a subject. After 10 min a small blood sample was taken and found to contain 5 x lO CPM/ml. Calculate the total blood volume of the individual. 

The calorimetric cell is initially filled with mg grams of solid and Mp grams of solvent (pure water or buffer/salt solution) mj° grams of water are adsorbed per unit mass of solid. The reservoir of the injection system contains a certain volume of the stock solution of molality C the solvent used to prepare this solution must be exactly the same as that in the cell. When the termal equilibrium has been reached in the whole calorimetric system (the baseline is steady), a precision syringe pump injects a small portion of the stock solution into the suspension. The mass of solute introduced into the cell is equal to... 

Parenteral suspensions and oil-based parenterals must be administered either subcutaneously or intramuscularly (see Sect. 13.5.3). The volume of subcutaneous injection typically amounts to 1 mL. To increase the applicable volume at the subcutaneous application site, hyaluronidase can be added to the formulation [1]. The volume of intramuscular injection is also small, usually 1-3 mL or up to 10 mL in divided doses. In practice the pharmacist also may dispense special injections (see Sect. 13.5.15). 

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