When Stella was originally on furosemide it was tablets. I ground them up, mixed them with water and syringed them. It takes a bit of time and patience as it's best done a little at a time, into the side of the mouth to avoid the teeth. Squirt too much in and it will just dribble out.
Do it at a time when you are feeling calm and not in a hurry. The trick is to accept it's going to take a little while and avoid it turning into a battle of wills.
You can sometimes get liquid versions of meds - I have a bottle of liquid furosemide but it was 50 quid as it was made up specially. But Stella is on it daily for life and it's a year's worth so it was worth it.
Paula