Monoclonal antibodies (mAbs) are laboratory-engineered proteins designed to bind to specific targets in the body, like cancer cells or inflammatory molecules. This targeted approach is used to treat many diseases, from autoimmune disorders to various cancers. The administration of these specialized drugs is a carefully considered process to ensure they work effectively.
Common Delivery Methods
Monoclonal antibody therapies are administered through two primary routes: intravenous (IV) infusion and subcutaneous (SC) injection. These methods are chosen to ensure the drug effectively reaches the bloodstream and its intended target. Each method has a distinct process suited for different situations.
Intravenous infusion administers the drug directly into a vein. This process is performed in a clinical setting, like a hospital or infusion center, by a healthcare professional. The mAb is diluted and delivered slowly over a period ranging from 30 minutes to several hours, which allows for safe delivery and patient monitoring.
Subcutaneous (SC) injections deliver medication into the fatty tissue just beneath the skin. This method uses a smaller volume of fluid and takes only a few minutes. Due to its simplicity, SC injections can sometimes be administered at home by the patient or a caregiver after training. The choice between IV and SC delivery depends on the specific drug, dosage, and patient factors.
The Rationale for Injection or Infusion
Patients often ask why monoclonal antibodies cannot be taken as a pill. The reason relates to their structure and the human digestive system. Monoclonal antibodies are large, complex protein molecules vulnerable to the harsh environment of the stomach and intestines.
The digestive tract is designed to break down proteins into smaller components, like amino acids, for absorption. Stomach acid and digestive enzymes would quickly dismantle an ingested monoclonal antibody. This degradation destroys the antibody’s Y-shaped structure, which is engineered to bind to its specific target. Consequently, the drug would be inactivated before it could enter the bloodstream and perform its therapeutic function.
This relates to bioavailability—the proportion of a drug that enters circulation to have an active effect. For orally administered mAbs, bioavailability is very low, making the treatment ineffective. Injection or infusion bypasses the digestive system, delivering the intact antibody directly into circulation. This ensures the drug is available to act on its target.
The Patient Experience
For patients undergoing intravenous infusion, the process occurs in a medical setting. An appointment begins with a healthcare professional inserting an IV line into a vein, usually in the arm. The infusion can be lengthy, and patients are monitored by nurses for any signs of a reaction.
Subcutaneous injections offer more flexibility. The process may start in a clinic where a nurse teaches the patient or a family member how to perform the injection. The injection is quick, using a small needle to deliver medication into the abdomen or thigh. Many patients find the convenience of at-home administration a benefit, reducing time spent in a clinic.
IV infusions require scheduling regular, sometimes lengthy, visits to a healthcare facility. SC injections require patients to become comfortable with self-administration or to coordinate with a caregiver. In both cases, communication with the healthcare team helps manage side effects and ensures the treatment plan is manageable.
Innovations in Delivery Technology
Drug delivery is evolving to make mAb therapies more effective and convenient. One advancement is the antibody-drug conjugate (ADC), which attaches a chemotherapy drug to a monoclonal antibody. The antibody seeks out cancer cells, delivering the cytotoxic agent directly to the tumor and minimizing damage to healthy tissue.
Another innovation makes subcutaneous injections more efficient. The enzyme hyaluronidase is now combined with some mAb formulations. This enzyme temporarily breaks down a substance in the subcutaneous tissue, allowing a larger drug volume to be injected and absorbed more rapidly. This can reduce administration time from hours to minutes, offering a more convenient option.
Researchers are exploring novel delivery systems to eliminate the need for needles. Microneedle patches, consisting of tiny needles that dissolve into the skin, are being developed to deliver mAbs transdermally. Inhaled delivery systems are also being investigated for certain diseases. These technologies aim to improve the patient experience by increasing comfort and convenience.