Hello Aspirant ,

You can gain good Knowledge in therapeutics only when you have good command on drugs,it's doses , it's regimens and also it's mechanism of actions , it's different dosage forms and it's adverse drug reactions ,

After getting complete knowledge about drugs ,
You can start treatment algorithms or treatment part which is nothing but therapeutics ,
When you study about drugs and it's treatment guidelines then it's called pharmacotherapeutics ,

Best books to study therapeutics is
pharmacotherapeutics by Dipiro,
Pharmacotherapeutics by Koda Kimble ,
And phaacotherapeutics by Ravi shankar,

These three books will have good way of explanation along which some good case studies in koda kimble ,

Prepare well dear ,

I wish you good luck ,

All the best !