The most common and most likely answer to this crossword clue is the 8 letter word WARFARIN
I've seen this crossword clue in Independent
W
A
R
F
A
R
I
N
More clues leading to the result WARFARIN
- Pest controller ceaselessly campaigning?
- Medication husband nicked from quay inside of marina
- Struggle endlessly to get popular anticoagulant
- Endless conflict over fashionable drug
- Drug mostly employed in theatre
- Battling endlessly to protect footballers from poison
- Inform in advance about travelling fair and a drug
- Poison in conflict well towards the centre?
Buddy explains!

The straight part
We know that "Medication" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case medication = warfarin.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does WARFARIN mean?
WARFARIN noun- A coumarin salt, warfarin sodium, found in certain clovers, that retards blood coagulation: