As of September 1, 2026, new rules regarding the use of hybrid drugs and biosimilars have taken effect in France. These are drugs that are similar to original biological medicines but are not exact copies. If a patient refuses to use a substitutable drug, they no longer benefit from third-party payment and must pay the full cost upfront. In some cases, the reimbursement may be based on the price of the most expensive drug in the group, leaving the patient with a remaining charge. However, third-party payment is still possible if the prescriber has marked the prescription as "non substitutable" in line with regulations or if the original drug is cheaper or equally priced. As of September 23, 2026, 13 biological groups are listed for substitution by pharmacists. These include drugs such as filgrastim, ranibizumab, étanercept, adalimumab, and others. The impact of substitution can vary depending on the specific disease, its stage, and how the drug is administered. Some patients may not understand why they are being offered a different drug than the one they have been using. Pharmacy teams must be well-informed about the available drugs, including their characteristics, injection methods, storage requirements, side effects, and precautions. This knowledge is crucial for explaining the differences between the original drug and the substitute. For example, the injection volume for a biosimilar of adalimumab must not exceed that of the original drug. For ustékinumab, it is important to ensure that treatment continues within the approved therapeutic range. For follitropine alfa, the substitution must allow for the exact administration of the prescribed dose, whether using single-dose or multi-dose pens. Pharmacy teams have identified certain drugs and situations that may lead to confusion or resistance. Substitution is often easier at the beginning of treatment, such as with enoxaparine prescribed for a short period after hospital discharge, rather than long-term treatments. The team is working to understand the reasons for patient reluctance, as some may interpret a change in medication as a sign of worsening health, leading to misuse, anxiety, or stopping treatment altogether. The language used can be a barrier. Terms like "biosimilar" or "biotherapy" may not be familiar to patients. Instead, it is better to explain that the drug is similar in effectiveness, quality, and safety to the original, ensuring the patient’s health remains the same. The change in reimbursement rules does not affect the treatment itself. The use of hybrid and biosimilar drugs helps prevent supply issues and ensures continued access to treatments. However, the economic benefits should be discussed carefully, as patients may feel these drugs are too costly for the healthcare system. The choice of a drug is not based only on cost but also on its acceptance by prescribers. For certain drugs, such as adalimumab, étanercept, and denosumab, manufacturers are required to provide fake administration devices to support patient use. Patient adherence is also influenced by hospital prescribers, especially oncologists, who are often familiar with biosimilars and may prescribe them early in treatment. Substitution can be easier when there is consistent information shared among the hospital, treating physician, pharmacist, and patient. Digital tools, such as secure messaging and online health platforms, can help streamline this communication.