Sultamicillin is the mutual prodrug of sulbactam and ampicillin. It is the tosylate salt of the double ester of sulbactam plus ampicillin. Sulbactam is a semisynthetic ß-lactamase inhibitor which, in combination with ampicillin, extends the antibacterial activity of the latter to include some ß-lactamase-producing strains of bacteria that would otherwise be resistant. The combination of sulbactam plus ampicillin for parenteral use has previously been shown to be clinically and bacteriologically effective in a variety of infections. Sultamicillin is marketed under a trade name Unasyn among others.