You're right they almost all end with similar letters. So second try!
You must name a medication (name brand or generic) that begins with the second letter of the previous medication.
Ex:
Lamotrigine
Aspirin
Sildenafil
Beginning: Ibuprofen
You must name a medication (name brand or generic) that begins with the second letter of the previous medication.
Ex:
Lamotrigine
Aspirin
Sildenafil
Beginning: Ibuprofen