Number + 剂 + Noun
The measure word 剂 (jì) is used to count doses of medicine, potions, or similar preparations. It pairs with a number or demonstrative and is placed before the noun it quantifies, much like other Chinese measure words.
医生给他开了三剂中药。
Yīshēng gěi tā kāi le sān jì zhōngyào.
The doctor prescribed him three doses of traditional Chinese medicine.
这剂疫苗需要冷藏保存。
Zhè jì yìmiáo xūyào lěngcáng bǎocún.
This dose of vaccine needs to be stored refrigerated.
她每天要吃两剂药才能控制病情。
Tā měitiān yào chī liǎng jì yào cáinéng kòngzhì bìngqíng.
She needs to take two doses of medicine every day to control her condition.