Metronidazole - An antibiotic / antiprotozoal drug. Used in the treatment of endocarditis and bacterial vaginosis.

Structure 

Simply remember the structure from it's name: ME-TRO-NIDAZOLE

IUPAC Name2-(2-methyl-5-nitro-1H-imidazol-1-yl)ethan-1-ol
metronidazole
i. Firstly, remember it is an Imidazole compound (azole in the name). 

ii. "ME" in the name represents, Methyl group at C-2 position.

iii. "TRO" represents, Nitro group at C-5 position.

iv. Lastly,  at N-1, put an ethyl alcohol. (Remember by, Ethyl after Methyl at C-2)