Synonyms: 5-Thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylicacid,3-[[(5-methyl-1,3,4-thiadiazol-2-yl)thio]methyl]-8-oxo-7-[(1H-tetrazol-1-ylacetyl)amino]-,monosodium salt, pentahydrate, (6R,7R)- (9CI); 5-Thia-1-azabicyclo[4.2.0]oct-2-ene-2-carboxylicacid,3-[[(5-methyl-1,3,4-thiadiazol-2-yl)thio]methyl]-8-oxo-7-[(1H-tetrazol-1-ylacetyl)amino]-,monosodium salt, pentahydrate, (6R-trans)-; Cefazolin sodium pentahydrate