Injection Site Reaction
An adverse effect at the location of drug injection, including redness, swelling, pain, itching, or tissue hardening. Injection site reactions are among the most commonly reported adverse events for injectable peptide drugs. Most are mild to moderate and resolve within days.
Technical Context
ISR mechanisms include: physical trauma (needle insertion causing tissue disruption), foreign body response (immune reaction to deposited material), pharmacological effect (local tissue response to the drug or excipients), and volume-related (distension of tissue by injected fluid — depot injections with larger volumes typically cause more ISRs). ISR management: site rotation (preventing cumulative damage), allowing refrigerated products to warm to room temperature before injection (cold products cause more pain), proper injection technique (correct depth, angle, speed), and application of cold packs post-injection for swelling. For GLP-1 RA pens, ISR rates are typically 1-5% in clinical trials. Depot injections (octreotide LAR, leuprolide depot) have higher ISR rates due to larger needle gauge, injection volume, and microsphere formulation.