Medicine, Drugs
noun, の adjective
A medicine dose is medicine or drugs you're taking.
やくざい
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
薬剤を使い終わったら、必ず薬剤入れに戻してください。
Make sure you put the medicine away in the medicine case after you use it.