Step 1: Recall the general rule.
Dry drugs are generally used in double the quantity of fresh or wet drugs in classical dosing
Step 2: Recall the exceptions.
A specific group of wet drugs is exempted from this doubling rule because of their potency or specific action
Step 3: State the exceptions.
This exception group is Guduchi, Kutaja and Vasa
\[ \boxed{Guduchi, Kutaja, Vasa} \]