MERCK'S PRIMAXIN (IMIPENEM/CILASTATIN) INJECTABLE ANTIBIOTIC CLEARS FDA NOV. 26

Merck's Primaxin (imipenem/cilastatin) cleared FDA Nov. 26 "for serious infections caused by susceptible strains of all major bacteria in virtually every major body site," the company announced in a same day press release. Merck said it expects the injectable antibiotic will be available in hospitals within two weeks. According to draft labeling, Primaxin is indicated for treatment of infections by susceptible organisms in lower respiratory tract infections, urinary tract infections, intra-abdominal infections, gynecological infections, bacterial septicemia, bone and joint infections, skin and skin structure infections, and endocarditis. Primaxin is priced at $14.95 for a 1/2 gm ampule. Dosage varies according to disease, to a maximum daily dose of 4 gm. The first marketed product of Merck's work with thienamycin, Primaxin has been touted by the company as "the antibiotic with the broadest spectrum known to medical research." The company said the drug was thus "particularly useful for treating mixed infections and for initial therapy before identification of the organisms causing the illness." Merck maintained that "other antibiotics do not provide such effectiveness with equal safety." According to Merck, Primaxin "has proved effective in killing bacterial strains resistant to penicillin, cephalosporin, cephamycin, and some other antibiotics." During trials on the combination antibiotic/kidney enzyme inhibitor, Merck said only one minor therapeutic hole was discovered: a "very rare" pseudomonas. In addition, Merck noted that "studies comparing Primaxin with other beta-lactam antibiotics and antimicrobial combinations also indicate it will be widely useful in the treatment of difficult and serious bacterial infections, including orgamisms -- common in hospitals -- that possess natural or acquired resistance to other antibiotics." Merck said that additional Primaxin studies are under way to "demonstrate new capabilities" of the drug, to provide an intramuscular dosage form, and to "document its cost-effectiveness in treatment." Primaxin is already marketed in West Germany, Austria and Switzerland. PRIMAXIN INDICATIONS FROM FDA LABELING The following is an excerpt from Primaxin draft labeling that includes indications for the treatment of infections in eight body sites caused by the susceptible organisms listed. LOWER RESPIRATORY TRACT INFECTIONS Staphylococcus aureus (penicillinase producing strains) Escherichia coli Klebsiella enterobacter Homophilus influenza Homophilus parainfluenza Acinetobacter species Serratia marcescens URINARY TRACT INFECTIONS Complicated and uncomplicated Staphylococcus aureus (penicillinase producing strains) Group D streptococci (enterococci) Escherichia coli Klebsiella Proteus vulgaris Providencia rettgeri Morganella morganii Pseudomonas aeruginosa INTRA-ABDOMINAL INFECTIONS Staphylococcus aureus Staphylococcus epidermidis Group D streptococci (enterococci) E. coli Klebsiella Proteus species (indole positive and indole negative) Morganella morganii Pseudomonas aeruginosa Citrobacter species Clostridium species Gram positive anerobes, including Peptococcus, Peptostreptococcus, Eubacterium, Propionibacterium, Bifidobacterium Bacterioid species, including b. fragilis Fusobacterium species GYNECOLOGICAL INFECTIONS Staphylococcus aureus Staphylococcus epidermidis Group B streptococci Group D streptococci (enterococci) E. coli Klebsiella Proteus species (indole positive and indole negative) Enterobacteriaceae species Gram positive anerobes, including Peptococcus and Peptostreptococcus, Propionibacterium, Bifidobacterium Bacterioid species, including b. fragilis Gardnerella vaginalis BACTERIAL SEPTICEMIA Staphylococcus aureus Group D streptococci E. coli Klebsiella Pseudomonas aeruginosa Serratia species Enterobacteriaceae species Bacterioid species, including b. fragilis BONE AND JOINT INFECTIONS Staphylococcus aureus Staphylococcus epidermidis Group D streptococci Enterobacteriaceae species Pseudomonas aeruginosa SKIN AND SKIN STRUCTURE INFECTIONS Staphylococcus aureus Staphylococcus epidermidis Group D streptococci E. coli Klebsiella Enterobacteriaceae species Proteus vulgaris Providencia rettgeri Morganella morganii Pseudomonas aeruginosa Serratia species Citrobacter species Acinetobacter species Gram positive anerobes, including Peptococcus, Peptostreptococcus Bacterioid species, including b. fragilis Fusobacterium ENDOCARDITIS Staphylococcus aureus