I take ziac (bisoprolol and hydrocholorthiazide) 10/6.25 tab 1 day can i take 300 mg of magnesium citrate?

Probably fine: Ziac (bisoprolol and hydrocholorthiazide) is a combination of a beta blocker and a thiazide diuretic (Bisoprolol and Hydrochlorothiazide). Typically, a magnesium supplement would not be expected to have an adverse reaction to this. Contact your physician for specific recommendation , especially if you have other medical conditions or laboratory abnormalities.