Intramuscular injection depot preparations

Leuprolide is available in solution for daily subcutaneous injection and in slow-release depot preparations in which leuprolide is lyophilized in microspheres given by intramuscular injection. 

The most important action is to ensure that the client receives appropriate pharmacological treatment. One of the main problems in schizophrenia is lack of medication compliance. This is often caused by lack of client collaboration, often explained by the intrinsic pathological characteristics of the disease itself. Both typical and atypical depot antipsychotics formulations are available. Depot preparations are typically administered by intramuscular injection every 1-4 weeks. This may be of great advantage in patients with poor compliance. 

Heparin and heparinoids are absorbed in only trace amounts when given in large doses orally . EDTA increases the absorption . Subcutaneous and intramuscular injection of various depot heparin preparations have not been found very satisfactory. They fail to give satisfactory blood levels and they increase Sensitization. With subcutaneous injection, the ability of heparin to become fixed to protein becomes a factor modifying absorption. One of the basic difficulties in deciding on the value of subcutaneous or intramuscular injections of heparin is that there has been no quantitative comparison made of the blood levels of heparin administered in these two ways, to determine how much appears in the circulation in active form. It is possible that much heparin never reaches the circulation. This is to be expected when it is remembered that heparin released by mast cells does not reach the circulation. Depository forms of heparin have been replaced by the use of concentrated heparin solutions (40 gm per cent), so that volumes of 0-2 to 0-4 ml. ean be injected into subcutaneous fat tissue or intramuscularly. 

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). 

Among the various approaches, major emphasis has been directed toward the development of parenteral repository or depot antimalarial substances. Such preparations consist typically of suspensions of repository compounds in aqueous or lipid vehicles. When these suspensions are injected intramuscularly or subcutaneously, the insoluble material is deposited in the tissues, forming a depot from which active principles are very slowly released into the circulation. In preparations of this type, it is essential that candidate substances be nonirritating to the tissues and imdergo minimal encapsulation. 

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