I think that the word "سكير" is more formal than the expression "بيشرب خمرة كتير". Also, there are other expressions that give the same meaning such as "مدمن خمر" or "خمورجى", but the latter word is less formal than all of these expressions (low slang language).

يمكن استخدام كلمة (مُدمِن) لأي نوع من المسكرات أو المخدرات 

<ul class="list-inline text-light-gray no-margin-b"><li>@ <a ui-sref="user({id:comment.commenter_obj.id})" href="https://www.italki.com/user/2933879" style="color: rgb(149, 149, 149); outline: 0px; outline-offset: -2px;">Maged</a>: برافو عليك</li></ul>

انت جيبت المعنى مظبوط

بتاع خمرة - هو ده

سكير isn't the exact word we normally do use in Egyptian, you're right it might be a bit derogatory, However you could say هو كان بيشرب كتير or هو كان متعود يشرب كتير