BMJ Group Medical Reference
Amlodipine makes your blood vessels relax and widen. This should help the blood flow to your fingers and toes. The brand name for this medicine is Istin. It's only available on prescription.
One study found that amlodipine reduced the number of attacks in people with Raynaud's phenomenon, but the study was very small.  More studies are needed to know for certain whether or not this treatment works.
Amlodipine can also cause side effects such as swollen ankles, flushing, and headaches. 
For references related to Raynaud's phenomenon click here