Pi Yanping has a patent, and the essential balm has been circulating for a long time, and no one has evidence to claim that it was invented by his own factory (the factory that invented it is estimated to have disappeared in War of Resistance against Japanese Aggression), so there is no patent. However, if you change the formula and use other herbs to prepare external medicine similar to essential balm, you should be able to apply for a patent, such as safflower oil.
I have never seen an analgesic ointment, but there must be various dosage forms, both traditional Chinese medicine and western medicine, which do not interfere with each other's patents.
It is much more troublesome to declare a patent as a drug than a general patent. Even over-the-counter drugs for external use require strict drug experiments and approval procedures, which can only be completed in cooperation with pharmaceutical companies.