import re

pattern = r"-?\b\d+(?:[.,]\d+)*\s*m?g(?:\s*/\s*-?\d+(?:[.,]\d+)*\s*m?g)+\b"

strings = [
    "Dexamethasonacetat 5 mg/10 mg, Lidocain-HCl 1H2O 30 mg/60 mg",
    "Anakinra 120 mg /-20 g /-12mg gentechnologisch hergestellt aus E. coli. 10mg pack"
]

for s in strings:
    print([re.sub(r"[\s-]+", "", m) for m in re.findall(pattern, s)])