Chapter 7. Parenteral Medication Administration Show Intramuscular (IM) injections deposit medications into the muscle fascia, which has a rich blood supply, allowing medications to be absorbed faster through muscle fibres than they are through the subcutaneous route (Malkin, 2008; Ogston-Tuck, 2014a; Perry et al., 2014). The IM site is used for medications that require a quick absorption rate but also a reasonably prolonged action (Rodgers & King, 2000). Due to their rich blood supply, IM injection sites can absorb larger volumes of solution, which means a range of medications, such as sedatives, anti-emetics, hormonal therapies, analgesics, and immunizations, can be administered intramuscularly in the community and acute care setting (Hunter, 2008; Ogston-Tuck, 2014a). In addition, muscle tissue is less sensitive than subcutaneous tissue to irritating solutions and concentrated and viscous medications (Greenway, 2014; Perry et al., 2014; Rodgers & King, 2000). The technique of IM injections has changed over the past years due to evidence-based research and changes in equipment available for the procedure. An IM site is chosen based on the age and condition of the patient and the volume and type of medication injected. When choosing a needle size, the weight of the patient, age, amount of adipose tissue, medication viscosity, and injection site all influence the needle selection (Hunter, 2008; Perry et al., 2014; Workman, 1999). Intramuscular injections must be done carefully to avoid complications. Complications with IM include muscle atrophy, injury to bone, cellulitis, sterile abscesses, pain, and nerve injury (Hunter, 2008; Ogston-Tuck, 2014a). With IMs, there is an increased risk of injecting the medication directly into the patient’s bloodstream. In addition, any factors that impair blood flow to the local tissue will affect the rate and extent of drug absorption. Because of the adverse and documented effects of pain associated with IM injections, always use this route of administration as a last alternative; consider other methods first (Perry et al., 2014). Sites for intramuscular injections include the ventrogluteal, vastus lateralis, and the deltoid site. Literature shows inconsistency in the selection of sites for deep muscular injections: selection may be based on familiarity and confidence rather than on “best practice” (Ogston-Tuck, 2014a). However, there is sufficient evidence that the ventrogluteal IM site is the preferred site whenever possible, and is an acceptable site for oily and irritating medications. The ventrogluteal site is free from blood vessels and nerves, and has the greatest thickness of muscle when compared to other sites (Cocoman & Murray, 2008; Malkin, 2008; Ogston-Tuck, 2014a). A longer needle with a larger gauge is required to penetrate deep muscle tissue. The needle is inserted at a 90-degree angle perpendicular to the patient’s body, or at as close to a 90-degree angle as possible. Use a quick, darting motion when inserting the needle. Aspiration refers to the action of pulling back on the plunger for 5 seconds prior to injecting medication (Ipp, Sam, & Parkin, 2006). Current practice in the acute care setting is to aspirate IM injections to check for blood return in the syringe. Lack of blood in the syringe confirms that the needle is in the muscle and not in a blood vessel. If blood is aspirated, remove the needle, discard it appropriately, and re-prepare and administer the medications (Perry et al., 2014). Recent research has found that there is no evidence to support the practice of aspiration, but despite policy changes, the procedure of aspiration continues to be taught and practised (Canadian Agency for Drugs and Technologies in Health, 2014; Greenway, 2014; Sepah, Samad, & Altaf, 2014; Sisson, 2015). Vaccinations and immunizations given by IM injections are never aspirated (Centers for Disease Control, 2015). The Z-track method is a method of administrating an IM injection that prevents the medication being tracked through the subcutaneous tissue, sealing the medication in the muscle, and minimizing irritation from the medication. Using the Z-track technique, the skin is pulled laterally, away from the injection site, before the injection; then the medication is injected, the needle is withdrawn, and the skin is released. This method can be used if the overlying tissue can be displaced (Lynn, 2011). IM Injection SitesTable 7.7 describes the three injection sites for IM injections. Table 7.7 Intramuscular Injection Sites
Special Considerations:
IM InjectionsConsider the type of medication and the age, condition, and size of the patient when selecting an IM site. Rotate IM sites to avoid complications. Potential complications include lingering pain, tissue necrosis, abscesses, and injury to blood vessels, bones, or nerves. If administering a vaccination, always refer to the vaccination guidelines for site selection. Checklist 58 outlines the steps to perform an IM injection. Checklist 58: Administering an Intramuscular Injection
Checklist 59 outlines the steps to perform a Z-track IM injection. Checklist 59: Administering a Z -Track Intramuscular Injection
Video 7.5Video 7.6Video 7.7
Additional VideosVideo 7.8How can drug absorption be improved?To overcome deficiencies of absorption due to drug properties, the dosage form may help improve absorption by altering the disintegration and dissolution time, increasing residence time in the intestine, and providing delayed release in the lower intestine instead of the stomach.
Why is medication absorbed faster through the intramuscular route than through the subcutaneous route?The intramuscular route of drug administration involves injecting the medicine directly into the muscle. As muscles are rich in large blood vessels, the absorption rate is faster than subcutaneous and intradermal routes.
What factor does the nurse know affects the absorption of a drug?Drug absorption rate is impacted by fluid status, lipid solubility, blood flow, and surface area.
What affects absorption rate of medication?Other physicochemical variables such as particle size and surface area, dissolution rate, amorphism, polymorphism characteristics, and nature of the dosage form will also affect systemic drug absorption.
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