There is a difference between biosimilar (biologics) and bio equivalent (conventional drugs).
Biologics are complicated and depending on the medicine may be impossible to replicate. Many of these types of medicines are used to treat chronic or serious diseases. These medicines are different from conventional medicines which can be tested to ensure the medicine behave in the same manner in the body. Can’t do that with biologics.
Biologics are created in a living system and minor changes to the process of making a biologics drug can significantly affect the the way the medicine functions in the body.
The whole idea behind generics is to lower costs. With the rigid demands required to ensure the medicine is processed in the exact manner as the original impresses me as adding an additional cost generic manufacturers may not follow. For biologics, the process is the product. Process controls remain confidential to the original manufacturer, therefore it is highly improbable or impossible to replicate the medicine by a second manufacturer.
One should proceed with caution when taking such a medicine. I have heard the same from doctors. “Similar” is a tricky term. So what is changed? Biologics differs from conventional medicines and should be carefully protected so patients do not become human guinea pigs. These medicines are meant to target specific parts of the immune system. Doctors do not know why or how some of these medicines work (at least medicines used to treat the nervous system). I had the pleasure and it went horribly wrong. Anecdotal yes, yet after hearing about other patients having problems, I err in the side of caution.