panic attacks

I quit drinking too and i was in the first year of uni when my panic attacks started so it was hard for me not to drink when it was very social.  I would say if i was you because you have been prescribed both citalopram (i am no doctor) and beta blockers to just cut out drinking until you make a full recovery.  Drinking actually makes panic attacks worse and because depression and anxiety are 2 ends of the same piece of string drinking could exasperate your anxiety/depressive symptoms (if you get those).     Personally, from reading you say your heart races every time you drink which suggests to me almost that you predict you will get anxiety everytime you drink but why don't you start on a drink with a lower alcohol content and see how you go/ what your limits are if you really are dead set on having a drink to relax.  A few drinks in moderation wont do you any harm, i speak from experience when taking propanalol and drinking at uni.   

Of course, alcohol withdrawal itself can also cause anxiety and panic attacks. Withdrawal anxiety is complicated, but it essentially comes from brain stress. Panic disorder is different from the normal fear and anxiety reactions to stressful events. Panic attack is a serious condition that strikes without reason or warning and symptoms of panic attacks are sudden attacks of fear and nervousness, as well as physical symptoms such as sweating and a racing heart.