Rasashastra means Ayurvedic Pharmaceutics and as such it deals mainly with the drugs of mineral origin, their varieties, characteristics, processing techniques, properties and their therapeutic uses along with the descriptions of various apparatus, different kinds of furnaces, heating devices and heating schedules.
Bhaishajya Kalpana is composed of two words, Bhaishajya – Drug and Kalpana – Processing. Processing means samskarana, done in order to establish the change in the qualities / properties of the drug either by inducing a new property or improving the existing one and finally making the drug safe and more effective.
Thus, Rasashastra and Bhaishajya Kalpana is the most important branch of learning in the field of Ayurveda. No drug can be formulated or cure any disease.
No branch of Ayurveda. can exist independently without the aid of Bhaishajya or Aushadha (medicinal preparations). Only a competent physician who has mastered the knowledge of different medicaments can treat all types of diseases. To save the lives of ailing people he should also have a thorough grip on the principles of the formulations and their practical application.
With the art and skill of formulation, a poisonous drug can be transmuted into a safe and effective drug. A simple drug can be converted into a most potent one. Therefore, Ayurveda, the Science of Health and Healing has given great emphasis to the comprehensive knowledge of drugs, preservation and dispensing of prepared drugs under the broad heading known as Rasashastra and Bhaishajya Kalpana.