Glycylcyclines: third-generation tetracycline antibiotics.

Although tetracycline antibiotics have some roles in human and veterinary medicine, the widespread emergence of microbial resistance has severely limited their effectiveness. A new generation of tetracyclines, the glycylcyclines, is being specifically developed to overcome problems of resistance to earlier tetracyclines. One of the glycylcyclines, 9-t-butylglycylamido-minocycline (GAR-936, tigilcycline), is currently undergoing clinical trials and microbiological, pharmacodynamic and pharmacokinetic data have recently been presented for several glycylcyclines, including GAR-936. An ongoing concern is whether resistance to glycylcyclines might arise in the future.