This is a question for those who are experts in the field of Rasa Shastra.[1][2] Just like questions regarding which poisons/toxins are injected into the human body as treatment, why, and for which illness are questions for experts in the appropriate specializations of modern medicine.
[1] A Text Book Of Rasa Shastra(Iatro-Chemistry And Ayurvedic Pharmaceutics) (https://chaukhamba.co.in/index.php?route=product/product&pro...)
[2] Introduction to ‘Rasashaastra’ the Iatrochemistry of Ayurveda (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3252715/)