Show the interaction types in decreasing order of frequency.
select interaction_type from medicine_enzyme_interaction group by interaction_type order by count(*) desc
Show the counts, too.
select interaction_type, count(*) from medicine_enzyme_interaction group by interaction_type order by count(*) desc
Only show the most frequent.
select interaction_type, count(*) from medicine_enzyme_interaction group by interaction_type order by count(*) desc limit 1