Tobramycin sulfate, a water-soluble antibiotic of the aminoglycoside group, is derived from the actinomycete Streptomyces tenebrarius. Sterile tobramycin sulfate is supplied as a sterile dry powder and is intended for reconstitution with 30 mL of Sterile Water for Injection, USP. Sulfuric acid and/or sodium hydroxide may have been added during manufacture to adjust the pH. † Each vial contains tobramycin sulfate equivalent to 1200 mg of tobramycin. After reconstitution, the solution will contain 40 mg of tobramycin per mL. The product contains no preservative or sodium bisulfite.

Tobramycin sulfate is 0-3-amino-3-deoxy-a-D-glucopyranosyl-(1?4)- 0-[2,6-diamino-2,3,6-trideoxy-a-D-ribo-hexopyranosyl-(1?6)]-2-deoxy- L-streptamine, sulfate (2:5)(salt) and has the chemical formula (C₁₈H₃₇N₅O₉)₂•5H₂SO₄. The molecular weight is 1425.45. The structural formula for tobramycin is as follows:

The pharmacy bulk package of tobramycin for injection USP is a container of a sterile preparation for parenteral use that contains multiple single doses. It is intended for use in a pharmacy admixture program. Package use is restricted to the preparation of admixures for intravenous infusion or to the filling of empty sterile syringes for intravenous injections for patients with individualized dosing requirements.