Gemifloxacin is an oral broad-spectrum quinolone antibacterial agent used in the treatment of acute bacterial exacerbation of chronic bronchitis and mild-to-moderate pneumonia. Gemifloxacin mesylate is marketed under the brand name Factive, indicated for the treatment of bacterial infection caused by susceptible strains such as S. pneumoniae, H. influenzae, H. parainfluenzae, or M. catarrhalis, S. pneumoniae (including multi-drug resistant strains [MDRSP]), M. pneumoniae, C. pneumoniae, or K. pneumoniae. Gemifloxacin has in vitro activity against a wide range of Gram-negative and Grampositive microorganisms. Gemifloxacin is bactericidal with minimum bactericidal concentrations (MBCs) generally within one dilution of the minimum inhibitory concentrations (MICs). Gemifloxacin acts by inhibiting DNA synthesis through the inhibition of both DNA gyrase and topoisomerase IV (TOPO IV), which are essential for bacterial growth. Streptococcus pneumoniae showing mutations in both DNA gyrase and TOPO IV (double mutants) are resistant to most fluoroquinolones. Gemifloxacin has the ability to inhibit both enzyme systems at therapeutically relevant drug levels in S. pneumoniae (dual targeting), and has MIC values that are still in the susceptible range for some of these double mutants.

Cefditoren pivoxil is a semi-synthetic cephalosporin antibiotic for oral administration. It is a 3rd generation cephalosporin that is FDA approved for the treatment of acute bacterial exacerbation of chronic bronchitis, community acquired pneumonia, infection of skin and/or subcutaneous tissue, and pharyngitis/tonsillitis. Cefditoren is a cephalosporin with antibacterial activity against gram-positive and gram-negative pathogens. The bactericidal activity of cefditoren results from the inhibition of cell wall synthesis via affinity for penicillin-binding proteins (PBPs). Common adverse reactions include diarrhea, nausea and candida vaginitis. Co-administration of a single dose of an antacid which contained both magnesium (800 mg) and aluminum (900 mg) hydroxides or co-administration of a single dose of intravenously administered famotidine (20 mg) reduced the oral absorption of a single 400 mg dose of cefditoren pivoxil administered following a meal. Co-administration of probenecid with cefditoren pivoxil resulted in an increase in the plasma exposure of cefditoren.

Sparfloxacin is a synthetic fluoroquinolone broad-spectrum antimicrobial agent in the same class as ofloxacin and norfloxacin. Sparfloxacin has in vitro activity against a wide range of gram-negative and gram-positive microorganisms. Sparfloxacin exerts its antibacterial activity by inhibiting DNA gyrase, a bacterial topoisomerase. DNA gyrase is an essential enzyme which controls DNA topology and assists in DNA replication, repair, deactivation, and transcription. Quinolones differ in chemical structure and mode of action from (beta)-lactam antibiotics. Quinolones may, therefore, be active against bacteria resistant to (beta)-lactam antibiotics. Although cross-resistance has been observed between sparfloxacin and other fluoroquinolones, some microorganisms resistant to other fluoroquinolones may be susceptible to sparfloxacin. In vitro tests show that the combination of sparfloxacin and rifampin is antagonistic against Staphylococcus aureus. The bactericidal action of sparfloxacin results from inhibition of the enzymes topoisomerase II (DNA gyrase) and topoisomerase IV, which are required for bacterial DNA replication, transcription, repair, and recombination. Sparfloxacin is used for the treatment of adults with the following infections caused by susceptible strains microorganisms: community-acquired pneumonia (caused by Chlamydia pneumoniae, Haemophilus influenzae, Haemophilus parainfluenzae, Moraxella catarrhalis, Mycoplasma pneumoniae, or Streptococcus pneumoniae) and acute bacterial exacerbations of chronic bronchitis (caused by Chlamydia pneumoniae, Enterobacter cloacae, Haemophilus influenzae, Haemophilus parainfluenzae, Klebsiella pneumoniae, Moraxella catarrhalis,Staphylococcus aureus, or Streptococcus pneumoniae). Sparfloxacin has trade names Spacin in Bangladesh, Zagam and Zagam Respipac. Zagam is no longer available in the United States.

Dirithromycin (Dynabac) is a macrolide glycopeptide antibiotic used to treat different types of bacterial infections, such as bronchitis, pneumonia, tonsillitis, skin infections. Dirithromycin is a semi-synthetic derivative of erythromycin - the hemi-aminal resulting from the condensation of (9S)-erythromycyclamine with 2-(2-methoxyethoxy) acetaldehyde. Being unstable under both acidic and alkaline conditions, dirithromycin functions as a more lipid-soluble prodrug for (9S)-erythromycyclamine. Erythromycylamine exerts its activity by binding to the 50S ribosomal subunits of susceptible mircoorganisms resulting in inhibition of protein synthesis. Dirithromycin has been shown to be active against most strains of the following microorganisms both in vitro and in clinical infections: Staphylococcus aureus (methicillin-susceptible strains only), Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Legionella pneumophila, Moraxella catarrhalis, and Mycoplasma pneumoniae. Dirithromycin showed better activity in vitro against Campylobacter jejuni and Borrelia burgdorferi than erythromycin or clarithromycin but in general demonstrated less activity than erythromycin, clarithromycin, or azithromycin against a majority of microorganisms. The pharmacokinetic profile of dirithromycin has advantages over other microlides of once-daily dosing and high and prolonged tissue concentrations but adverse effect profiles similar to those of the other macrolides, with reported problems most often related to the gastrointestinal tract.

Ceftibuten is a 3rd generation cephalosporin that is FDA approved for the treatment of acute bacterial exacerbations of chronic bronchitis, acute bacterial otitis media, pharyngitis and tonsillitis. Ceftibuten exerts its bactericidal action by binding to essential target proteins of the bacterial cell wall. This binding leads to inhibition of cell-wall synthesis. Common adverse reactions include diarrhea, nausea, vomiting and headache. The effect of increased gastric pH on the bioavailability of ceftibuten was evaluated in 18 healthy adult volunteers. Each volunteer was administered one 400-mg ceftibuten capsule. A single dose of liquid antacid did not affect the Cmax or AUC of ceftibuten; however, 150 mg of ranitidine q12h for 3 days increased the ceftibuten Cmax by 23% and ceftibuten AUC by 16%.

Lomefloxacin hydrochloride (marketed under the following brand names in English speaking countries Maxaquin, Okacyn, Uniquin) is a fluoroquinolone antibiotic used to treat bacterial infections. It is used to treat chronic bronchitis, as well as complicated and uncomplicated urinary tract infections. It is also used as a prophylactic or preventative treatment to prevent urinary tract infections in patients undergoing transrectal or transurethral surgical procedures. Flouroquinolones such as lomefloxacin possess excellent activity against gram-negative aerobic bacteria such as E.coli and Neisseria gonorrhoea as well as gram-positive bacteria including S. pneumoniae and Staphylococcus aureus. They also posses effective activity against shigella, salmonella, campylobacter, gonococcal organisms, and multi drug resistant pseudomonas and enterobacter. Lomefloxacin is a bactericidal fluoroquinolone agent with activity against a wide range of gram-negative and gram-positive organisms. The bactericidal action of lomefloxacin results from interference with the activity of the bacterial enzymes DNA gyrase and topoisomerase IV, which are needed for the transcription and replication of bacterial DNA. DNA gyrase appears to be the primary quinolone target for gram-negative bacteria. Topoisomerase IV appears to be the preferential target in gram-positive organisms. Interference with these two topoisomerases results in strand breakage of the bacterial chromosome, supercoiling, and resealing. As a result DNA replication and transcription is inhibited.

Enoxacin is an oral broad-spectrum fluoroquinolone antibacterial agent used in the treatment of urinary tract infections and gonorrhea. Enoxacin is bactericidal drugs, eradicating bacteria by interfering with DNA replication. Like other fluoroquinolones, enoxacin functions by inhibiting bacterial DNA gyrase and topoisomerase IV. The inhibition of these enzymes prevents bacterial DNA replication, transcription, repair and recombination. Enoxacin is active against many Gram-positive bacteria. After oral administration enoxacin is rapidly and well absorbed from the gastrointestinal tract. The antibiotic is widely distributed throughout the body and in the different biological tissues. Tissue concentrations often exceed serum concentrations. The binding of enoxacin to serum proteins is 35 to 40%. The serum elimination half-life, in subjects with normal renal function, is approximately 6 hours. Approximately 60% of an orally administered dose is excreted in the urine as unchanged drug within 24 hours. Enoxacin, like other fluoroquinolones, is known to trigger seizures or lower the seizure threshold. The compound should not be administered to patients with epilepsy or a personal history of previous convulsive attacks as may promote the onset of these disorders.

Loracarbef (KT3777) is carbacephem antibiotic structurally identical to cefaclor, except that the sulfur atom of position 1 of the cephem nucleus has been replaced by carbon. It showed good affinity for penicillin-binding proteins. At low concentrations (< 2 mg/L) in vitro, it inhibits Streptococcus pneumoniae, S. pyogenes, beta-haemolytic streptococci groups B, C and G. Proteus mirabilis and Moraxella catarrhalis, including beta-lactamase-producing strains. At therapeutic plasma concentrations it is also active in vitro against most strains of Staphylococcus aureus, S. saprophyticus, Escherichia coli and beta-lactamase-positive and -negative strains of Haemophilus influenzae. Loracarbef has been indicated in the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms.

Cefmetazole is a semisynthetic cephamycin antibiotic. It has a broad spectrum of activity comparable to that of the second-generation cephalosporins, covering gram-positive, gram-negative, and anaerobic bacteria. Its bactericidal action results from inhibition of cell wall synthesis. It effectively treats abdominal and respiratory tract infections, pelvic inflammatory disease, urinary tract infections, skin and soft tissue infections and used for surgical prophylaxis, reducing or eliminating signs and symptoms of infection. Cefmetazole has a low frequency of adverse effects, and a side effect profile similar to that of other cephamycins. Adverse effects following overdosage have included nausea, vomiting, epigastric distress, diarrhea, and convulsions.

Cefpiramide or SM-1652 (sodium 7-[D(-)-alpha-(4-hydroxy-6-methylpyridine-3-carboxamido)-alpha-(4-hydroxyphenyl)acetamido]-3-[(1-methyl-1H-tetrazol-5-yl) thiomethyl]-3-cephem-4-carboxylate) is a semisynthetic cephalosporin derivative with a broad spectrum of antibacterial activity. This antibiotic has been reported to have potent in vitro and in vivo antibacterial activities against gram-positive and -negative bacteria.