What Causes Dizziness On Standing While Taking Clonidine?

Thank you sir. My husband picked up one of his scriptions. In the past it always says; Valsartan/HTZ 320/25mg. Today he picked it up with a change (it was not a new order, just a refill) Valsartan-Hydrochloroth320-25. This also occured on another refill; was Clonidine 0.3mg. This time it says, Clondine HCL 0.3mg. The scary thing is he complained of being dizzy, especially upon standing, As I have ACAD I have a BP cuff. I took his sitting, 73 over 44 Pulse 78. Standing, 74 over 43. I had called the pharmacy upon bringing them home, and they stated it was the same medicine. He is currently on a combination of 5 medications to keep his BP in check. It took quite awhile to hit on the combo, but has worked for years. Is there a difference in the medications?