Therapeutic injections product solutions

Intravenous aqueous injections provide an excellent means of achieving a rapid therapeutic response. Parenteral product design, eg, vehicle and other excipient selection, as well as choice of route of adrninistration, can prolong therapeutic activity and increase onset times. Thus, oily solutions, suspensions, or emulsions can be adrninistered by subcutaneous or intramuscular routes to create prolonged effect, ie, depot injection (28). 

The U.S. Pharmacopoeia (USP) classifies injections into five different types. The dosage form selected for a particular drug product is dependent upon the characteristics of the drug molecule (e.g., stability in solution, solubility, and injectability), the desired therapeutic effect of the product (e.g., immediate vs. sustained release), and the desired route of administration. Solutions and some emulsions (e.g., miscible with blood) can be injected via most parenteral routes of administration. Suspensions and solutions that are not miscible with blood (e.g., injections employing oleaginous vehicles) can be administered via intramuscular or subcutaneous injection but should not be given intravenously. 

Toxicity from local anesthetics (other than cocaine) is usually caused by therapeutic overdosage (ie, excessive doses for local nerve blocks), inadvertent acceleration of intravenous infusions (lidocaine), or accidental injection of products meant for dilution (eg, 20% lidocaine) instead of those formulated for direct administration (2% solution). Acute injection of lidocaine has also been used as a method of homicide. 

---