Terribly sick ape swallows vitamin and first aid items (3,5)

'aid items' is the definition.
The definition and answer can be both man-made objects as well as being plural nouns.
Perhaps there's a link between them I don't understand?

'terribly sick ape swallows vitamin and first' is the wordplay.
I cannot really understand how this works, but
an anagram of 'ape' is 'epa' which is located in the answer.
'first' could be 'i' (I in Roman numerals eg Elizabeth I) and 'i' is present in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?