４時間おきにこの薬をのみなさい。

four

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

this (something or someone close to the speaker (including the speaker), or ideas expressed by the speaker)

medicine; pharmaceuticals; (legal) drugs; efficacious chemical (i.e. gunpowder, pesticide, etc.); (pottery) glaze; small bribe

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

to drink; to gulp; to swallow; to take (medicine); to smoke (tobacco); to engulf; to overwhelm; to keep down; to suppress; to accept (e.g. demand, condition); to make light of; to conceal

to do