I am now 83. After some difficulty finding a medication which would reduce my blood pressure I was prescribed amlodipine besylate with excellent results. Initially 5 mg but I am now on the 10 mg tablet. I have been taking this medication for about 15 years but the doctor has now changed the prescription to amlodipine mesilate. I appreciate the besylate is more expensive but wish to know what medical difference this change might make please.