The US Food and Drug Administration (FDA) approved Tygacil (tigecycline), a novel IV antibiotic with a broad spectrum of antimicrobial activity, including activity against the drug-resistant bacteria methicillin-resistant Staphylococcus aureus (MRSA).

Tygacil is indicated for the treatment of complicated intra-abdominal infections (cIAI) and complicated skin and skin structure infections (cSSSI) in adults. Approval of this first-in-class product comes at a time when the need for new antibiotic options to combat serious, resistant infections is increasing, a Wyeth release said.

"Life threatening infections are a growing concern globally," says Dr Joseph Camardo, senior vice president, Global Medical Affairs, Wyeth Pharmaceuticals. "Bacterial infections are becoming more difficult to treat, with resistant strains on the increase. The approval of Tygacil will provide physicians with an important option for patients with complicated skin, skin structure, and intra-abdominal infections."

Tygacil can be used as an empiric monotherapy to treat a variety of cIAI and cSSSI, both hospital- and community-acquired, including complicated appendicitis, infected burns, intra-abdominal abscesses, deep soft tissue infections, and infected ulcers. Tygacil provides clinicians with a novel, broad-spectrum option that can be used at the onset of treatment when the specific bacteria present are not yet known. In addition, Tygacil does not require dosage adjustment in patients with impaired renal function, and is conveniently dosed every 12 hours.

The US Centers for Disease Control and Prevention (CDC) states that persons infected with drug-resistant organisms are more likely to have longer hospital stays and require treatment with multiple drugs. The increasing prevalence of resistant bacteria often necessitates the use of combinations of antibiotics to fight infections. Antibiotic resistance costs US society between $4 billion and $5 billion annually. According to the CDC, antibiotic resistance has become so widespread that many significant bacterial infections in the world are becoming resistant to commonly used antibiotics.

Additionally, few broad-spectrum antibiotic agents are currently in development. Antibiotic development has slowed to the point that FDA has had few opportunities to approve new agents. In fact, development and approvals of new antibacterial agents have decreased by 56 per cent over the past 20 years (1998-2002 vs. 1983-1987). New classes of antibiotics are needed to address increasing antibiotic resistance among common pathogens.

Tygacil, the first antibiotic approved in a new class called glycylcyclines, was developed by Wyeth to overcome key mechanisms of resistance that have affected antibiotic use.

Tygacil is approved for adults with complicated skin and skin structure infections (cSSSI) caused by Escherichia coli, Enterococcus faecalis (vancomycin-susceptible isolates only), Staphylococcus aureus (methicillin-susceptible and -resistant isolates), Streptococcus agalactiae, Streptococcus anginosus grp. (includes S anginosus, S intermedius, and S constellatus), Streptococcus pyogenes, and Bacteroides fragilis.

Tygacil is also approved for adults with complicated intra-abdominal infections (cIAI) caused by Citrobacter freundii, Enterobacter cloacae, Escherichia coli, Klebsiella oxytoca, Klebsiella pneumoniae, Enterococcus faecalis (vancomycin-susceptible isolates only), Staphylococcus aureus (methicillin-susceptible isolates only), Streptococcus anginosus grp. (includes S anginosus, S intermedius, and S constellatus), Bacteroides fragilis, Bacteroides thetaiotaomicron, Bacteroides uniformis, Bacteroides vulgatus, Clostridium perfringens, and Peptostreptococcus micros.

The Tygacil New Drug Application (NDA) submission included data from four pivotal phase III studies examining the safety and efficacy of Tygacil for the treatment of cIAI and cSSSI. The submission also included in vitro data showing activity against both gram-negative and gram-positive bacteria, anaerobes, and certain drug-resistant pathogens.

In clinical trials, empiric monotherapy with Tygacil provided comparable clinical cures rates in cSSSI to vancomycin and aztreonam, a combination treatment. Empiric monotherapy with Tygacil also provided clinical cure rates comparable to imipenem/cilastatin, an empiric treatment for cIAI. The overall discontinuation rate for Tygacil (5.0 per cent) was comparable to vancomycin and aztreonam (5.3 per cent) and imipenem/cilastatin (4.4 per cent).

Wyeth now awaits decisions on approval of Tygacil from other regulatory bodies around the world. Tygacil was accepted by the European Medicines Agency (EMEA) for review, and Wyeth has filed for approval in other countries, including Brazil, Canada, Colombia, Mexico, Switzerland, Taiwan, and Venezuela. The Australian Therapeutic Goods Administration and the South African Medicines Control Council (MCC) granted priority evaluation to Tygacil. Wyeth anticipates that Tygacil will be available to hospitals in the US in the near future.