Hello,
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Norvasc is a Calcium Channel Blocker and is used for treating High Blood Pressure/chest pain and other heart conditions.If you have complains of high Blood pressure it must be prescribed for that.
Regarding the fluctuation normal blood pressure fluctuates and changes several times in a day and varies with different activities as increases with exercise,food etc.If after the medication you are feeling better and do not have any complaints then it is fine.If anytime the blood pressure readings are continuously on the higher side for few days inspite of taking the medication that is more than 150/100 then you need to be concerned of and get yourself clinically examined.
Hope this answers your query.
Take care!