I would try behavior modification before medication.
When I leave or when I come home I do not make a big deal about it. Just come and go. No long drawn out good-byes it just upsets them. Coming home I just do a few normal things first and then I sit down and say hello calmly, no "I missed you sooo much" stuff.
When you are gone try leaving a tv or radio on. also leave a worn piece of clothing with your scent on it.
Hope this helps.
