Whenever your blood pressure is high,all efforts should be done to bring it to normal so as to avoid various complications arising out of uncontrolled hypertension
Whenever any drug for blood pressure is started for first time,it has a pronounced action early on which becomes stabilised gradually.It is because of this reason your blood pressure is showing such a fall with first dose.
You should keep taking this medicine and abide by the instructions of your doctor.
The ideal and proper blood pressure in a person is below 120/80 mm of Hg.
Keep a regular date with your treating doctor.