I could not identify a medicine named “Rotavelian”. Please check the spelling or share a photo of the ampoule/box.

You may mean Rotav (drotaverine) injection, which is used for relief of smooth-muscle spasms such as:

Welset injection contains paracetamol (acetaminophen). It is used short-term for:

Welset should be given by a healthcare professional. Avoid taking additional paracetamol-containing tablets/syrups at the same time unless prescribed, because overdose can seriously damage the liver. Use extra caution or avoid it in significant liver disease or heavy alcohol use.