In 1844, Irish physician Francis Rynd invented the hollow needle and used it to make the first recorded subcutaneous injections, specifically a sedative to treat neuralgia. In 1853, Charles Pravaz and Alexander Wood independently developed medical syringes with a needle fine enough to pierce the skin.
Drug injection is a method of introducing a drug into the bloodstream via a hollow hypodermic needle, which is pierced through the skin into the body. Injections generally administer a medication as a bolus (or one-time) dose, but can also be used for continuous drug administration. After injection, a medication may be designed to be released slowly, called a depot injection, which can produce long-lasting effects.
If you’re living with a chronic condition, your doctor might prescribe injectable medication rather than medication taken by mouth. This allows medication to be absorbed directly into the bloodstream, which can make it more fast-acting than oral medication. Some injectable medications are formulated to release their active ingredients slowly over time rather than all at once.
What are the types of injection?
Injections can be given in several ways. How a medicine is injected depends on a variety of factors including:
• How the drug is made
• How quickly the medication takes effect
• How much liquid is in the injection
The three main types of injections include:
• Subcutaneous (into the fat layer between the skin and muscle)
• Intramuscular (deep into a muscle)
• Intravenous (through a vein)
What is the difference between subcutaneous and intramuscular injections?
Intramuscular injections are absorbed faster than subcutaneous injections. This is because muscle tissue has a greater blood supply than the tissue just under the skin. Muscle tissue can also hold a larger volume of medication than subcutaneous tissue.
The speed of absorption is faster for intramuscular injection compared to subcutaneous injection, therefore making intramuscular the preferred method for some/most injections.
Intramuscular injections offer some benefits over other types of delivery methods, such as oral, intravenous injections into a vein, and subcutaneous injections into fatty tissue under the skin.
A doctor may use an intramuscular shot if:
- They cannot locate an appropriate vein
- The particular drug would irritate the veins
- The digestive system would render pills ineffective
Intramuscular injections have other advantages too. The muscles have a plentiful supply of blood, which helps ensure that the body absorbs the medication quickly. The tissue in the muscles can also hold more medication than fatty tissue. Doctors administer most injectable vaccines into the muscles.
Some injections can be administered by yourself at home, but some require a medical professional to give the injection either at your home or in their office. Please speak to your doctor or pharmacist before injecting if you have questions about how to administer your medication.
Safe Injection Practice
Unsafe injection practices and injection overuse are widespread in some countries especially developing countries harming the patient and inviting risks to the health care workers. Safe injection practices are intended to prevent transmission of infectious diseases between one patient and another, or between a patient and health care personnel during preparation and injection of medications. health care personnel most frequently handle parenteral medications when administering local anesthesia, during which needles and anesthetic cartridges are used for one patient only, and the dental cartridge syringe is cleaned and heat-sterilized between patients.
Other safe practices apply to use of injected medications in IV fluids, such as for patients undergoing conscious sedation. A safe injection does not harm the recipient and does not expose health care personnel to any avoidable risks.
Centers for Disease Control and Prevention’s (CDC’s) safe injection practice recommendations are:
- Prepare injections using aseptic technique in a clean area.
- Disinfect the rubber septum on a medication vial with alcohol before piercing.
- Do not use needles or syringes for more than one patient (this includes manufactured prefilled syringes and other devices such as insulin pens).
- Medication containers (single and multidose vials, ampules, and bags) are entered with a new needle and new syringe, even when withdrawing additional doses for the same patient.
- Use single-dose vials for parenteral medications when possible.
- Do not use single-dose (single-use) medication vials, ampules, and bags or bottles of intravenous solution for more than one patient.
- Do not combine the leftover contents of a single-use vials for later use.
- The following apply if multidose vials are used:
- Dedicate multidose vials to a single patient whenever possible.
- If multidose vials will be used for more than one patient, they should be restricted to a centralized medication area and should not enter the immediate patient treatment area (e.g., dental operatory) to prevent inadvertent contamination.
- If a multidose vial enters the immediate patient treatment area, it should be dedicated for single-patient use and discarded immediately after use.
- Date multidose vials when first opened and discard within 28 days, unless the manufacturer specifies a different date.
- Do not use fluid infusion or administration sets (e.g., IV bags, tubings, connections) for more than one patient.
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