Medicine
Dose
noun, suffix
If you take a dose of something, you are taking a dose of medicine. Take your cough syrup, child!
The reading is the same one you learned with the kanji, probably because it's attached to things usually, so it's treated like on'yomi.
解毒剤の極秘開発を行う予定だとちょいと小耳に挟みましたよ。
I heard it through the grapevine that you guys are going to do some hush-hush antidote experiments.