Lauha kalpas are preparations of Loha Bhasma as main ingredient added to other drugs. The drugs are reduced to fine powder and mixed with loha bhasma. Bhavana is given with prescribed liquids mentioned.
Powder should be very fine and the bhasma used should be well prepared. When well protected from moisture and heat, they keep their potency for a period of 2 years. Preparations containing mercury or its compounds keep their potency indefinitely