Viagra's reformulated around another drug to produce ups and downs (8)
I believe the answer is:
vagaries
'ups and downs' is the definition.
(I've seen this in another clue)
'viagra's reformulated around another drug' is the wordplay.
'reformulated' indicates anagramming the letters.
'around another drug' becomes 'es' (I can't justify this - if you can you should believe this answer much more).
'viagra' is an anagram of 'vagari'.
'vagari'+'es'='VAGARIES'
'to produce' acts as a link.
Can you help me to learn more?
(Other definitions for vagaries that I've seen before include "Capricious acts or ideas" , "Unpredictable acts" , "uncertainties" , "unpredictable changes" , "Whims" .)