Merck & Co., Inc. has announced that the US Food and Drug Administration (FDA) recently approved Invanz (ertapenem). It is a once-daily injectable antibiotic, for the prophylaxis of surgical site infection (SSI) following elective colorectal surgery in adults.

This approval was based upon the results of the landmark Prevent trial, the largest prospective, randomised double-blind, comparative clinical trial ever conducted in antibiotic prophylaxis for elective colorectal surgery. Results from the study were presented in the New England Journal of Medicine.

"Given the high incidence of SSI, Merck is very pleased to be able to offer a new alternative with clinically demonstrated efficacy," said Murray A. Abramson, MD, MPH, senior medical director, Merck Research Labs, Infectious Diseases, Merck & Co. Inc.

In the Prevent study, a statistically significant difference favouring Invanz over cefotetan with respect to the primary endpoint has been observed. A second adequate and well-controlled study to confirm these findings has not been conducted; therefore, the clinical superiority of ertapenem over cefotetan has not been demonstrated. Invanz provides proven prophylaxis for elective colorectal surgery in a single 1 g dose given within one hour prior to surgical incision.

The primary endpoint in the Prevent study was the test of prophylaxis, which was defined as no evidence of SSI, post-operative anastomotic leak, or unexplained antibiotic use through four weeks post-surgery in the clinically evaluable and MITT populations. The rates of successful prophylaxis at 4 weeks post treatment in the clinically evaluable patients were 70.5 per cent (244/346) for ertapenem and 57.2 per cent (194/339) for cefotetan.

In the MITT analysis, the prophylactic success rates at 4 weeks post treatment were 58.3 per cent (263/451) for ertapenem and 48.9 per cent (220/450) for cefotetan (difference 9.4 per cent.

Prophylaxis failure due to SSI, including superficial incisional, deep incisional or organ space infections, occurred in 18.2 per cent (63/346) of ertapenem patients and 31 per cent (105/339) of cefotetan patients. Post-operative anastomotic leak occurred in 2.9 per cent (10/346) of ertapenem patients and 4.1 per cent (14/339) of cefotetan patients. Unexplained antibiotic use occurred in 8.4 per cent (29/346) and 7.7 per cent (26/339) of ertapenem and cefotetan patients, respectively.

Invanz is now indicated in adults for the prophylaxis of surgical site infection following elective colorectal surgery. Elective colorectal (gastrointestinal) surgery is performed to repair or remove diseased portions of the lower intestinal tract (including the colon, rectum and anus) sometimes due to cancer or diverticulosis.

The incidence of surgical site infection has become a focus of the National Surgical Infection Prevention Project implemented by the Centres for Medicare and Medicaid Services in collaboration with the Centres for Disease Control and Prevention to promote the proper use of prophylactic antibiotics.

Invanz is contraindicated in patients with known hypersensitivity to any component of this product or to other drugs in the same class or in patients who have demonstrated anaphylactic reactions to beta-lactams. Due to the use of lidocaine HCl as diluents, Invanz administered intramuscularly is contraindicated in patients with known hypersensitivity to local anaesthetics of the amide type. Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving therapy with beta-lactams.

Invanz, a carbapenem related to the class of antibiotics known as beta-lactams, is generally given to adults as a 1-gram dose, once-a-day, by intravenous infusion or intramuscular.