Cetocycline, tetracycline analog: in vitro studies of antimicrobial activity, serum binding, lipid solubility, and uptake by bacteria.

Cetocycline (formerly chelocardin or cetotetrine) is structurally related to the tetracyclines. It was found to be more active than tetracycline against many clinical isolates of aerobic gram-negative bacilli, but is less active against staphylococci, and has no activity against Pseudomonas. It is bactericidal against susceptible enteric gram-negative bacteria at concentrations two to four times higher than the minimal inhibiting concentrations. The drug is highly lipid soluble; more than 80% is bound to serum, and it is more avidly taken up by susceptible bacteria than tetracycline. A direct correlation between drug uptake and susceptibility of bacteria was not noted, except with a strain of Proteus vulgaris.