Much of oncology nursing education focuses on IV administration of systemic therapies because for years, that was the only route. Until 2004, only two cancer therapies were approved for subcutaneous (SC) administration, and just nine others were added through 2012. However, as more familiar IV therapies get SC counterparts, including the more recent approvals of four high-volume monoclonal antibodies (mAbs), infusion nurses are using them more regularly in practice.
In his article in the December 2021 issue of the Clinical Journal of Oncology Nursing, Eisenberg discussed the history of SC cancer therapies, the role of hyaluronidase in many of today’s preparations, and administration techniques for optimal patient comfort.
Why Some Cancer Drugs Are SC
Administration by injection has several advantages over infusion, Eisenberg outlined. Studies have shown that it reduces time on both the provider and institutional side (e.g., pharmacy preparation time, overall cost, chair time) and patient side (e.g., chair time, convenience). Some therapies produce fewer side effects when given as an SC injection (e.g., peripheral neuropathy, infusion reactions). Eisenberg said that SC administration slows absorption, lowers the maximum concentration of the drug, and creates a sustained concentration trough, which may even improve outcomes.
Because of the concern for injection site reactions and extravasation, high-volume administrations like mAbs couldn’t be given through the SC route. However, the addition of recombinant hyaluronidase changes that. Hyaluronidase breaks down hyaluronic acid, Eisenberg explained, facilitating fluid transmission within tissues. He added that each of the new SC mAbs require a fixed hyaluronidase dose specific to the mAb agent, which is why the doses include it directly in the preparation from the manufacturer.
What Nurses Should Know About SQ Tissue
SC administration is all about the tissue. Assigned males have less SC tissue than assigned females, and for both sexes the tissue’s thickness varies based on injection site, Eisenberg said. And as patients age, SC tissue thins, which may increase risk of inadvertent intramuscular injection despite using recommended methods and techniques.
SC Administration Techniques
Eisenberg described three administration considerations for SC injections.
Pinch technique: The best approach for patients with thinner SC tissue, the pinch technique involves pinching 1–2 inches of skin between the thumb and forefinger to lift it off the muscular tissues beneath it. The injection is delivered at either a 45- or 90-degree angle into the SC tissue while it is still pinched.
“Proper technique requires that the muscle is not inadvertently pinched along with SC tissue,” Eisenberg said.
Air lock or air sandwich technique: Recommended specifically for bortezomib, the air lock technique uses a small bubble (0.2–0.3 ml) of air at the end of the syringe as a seal to keep the injected fluid within the SC tissue. The technique reduces the risk of injection site reactions and patient discomfort.
Slow and fast techniques: Injecting the drug slowly allows it to distribute vertically within the SC tissue, typically resulting in less pain for patients. Faster injections force the drug into a horizontal pattern, which injures more tissue and causes more pain and bruising. This is particularly important for high-volume SC injections like those used for mAbs, and Eisenberg cited several studies demonstrating the evidence for the approach.
To make a long injection time more comfortable for the nurse, Eisenberg suggested using a winged or butterfly infusion set. He also advised preparing patients to understand how long the injection will take.
Nursing Interventions for More Comfortable SQ Administration
Eisenberg added specific nursing strategies to help reduce discomfort for patients who find injections painful, particularly when large volumes are used, which are outlined in the sidebar. Eisenberg cautioned that the use of heat or ice on the injection site to alleviate any postinjection discomfort—a commonsense strategy in many patients’ and practitioners’ toolkits—is actually contraindicated for most medications because it may alter the pharmacokinetic properties. He advised referring to the package insert for the manufacturer’s recommendations for heat or cold therapy.
For more information about the history of SC cancer therapies and illustrations depicting the techniques discussed in this summary, refer to Eisenberg’s full article.