(R)-9-(2-Phosphonylmethoxypropyl)adenine (PMPA known as tenofovir) is an antiviral drug. Diphosphate of PMPA acts as a selective inhibitor of the HIV-1 reverse transcriptase. Tenofovir disoproxil was approved for clinical use for the treatment of HIV infection (AIDS) and chronic HBV infection.

Amprenavir is an inhibitor of HIV-1 protease. Amprenavir binds to the active site of HIV-1 protease and thereby prevents the processing of viral gag and gag-pol polyprotein precursors, resulting in the formation of immature non-infectious viral particles. Amprenavir-containing combination regimens have shown virological efficacy, and have generally been well tolerated, in patients with HIV infection (primarily treatment-naive or protease inhibitor-naive). Fosamprenavir (GW433908, Lexiva, Telzir) is an oral prodrug of amprenavir, with a reduced daily pill burden. The use of protease inhibitors has also been associated with dyslipidemia and an increased risk of cardiovascular disease. Amprenavir activates Pregnane X receptor to mediate dyslipidemia.

Gatifloxacin is a recently developed antibacterial agent differing from earlier fluoroquinolones by the presence of a methoxy group at the C-8 position. The presence of the methoxy group has conferred improved antibacterial activity against both Gram-positive and Gram-negative organisms, making gatifloxacin a broad-spectrum antimicrobial agent applicable in many clinical settings. Gatifloxacin is sold under the brand Zymar and is indicated for the treatment of bacterial conjunctivitis caused by susceptible strains of the following organisms: Aerobic Gram-Positive Bacteria: Cornyebacterium propinquum, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mitis, Streptococcus pneumoniae and Aerobic Gram-Negative Bacteria: Haemophilus influenza. The antibacterial action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase, which allows the untwisting required to replicate one DNA double helix into two. Notably the drug has 100 times higher affinity for bacterial DNA gyrase than for mammalian. In addition, Gatifloxacin inhibits bacterial topoisomerase IV. This enzyme is an enzyme known to play a key role in the partitioning of the chromosomal DNA during bacterial cell division. The mechanism of action of fluoroquinolones including gatifloxacin is different from that of aminoglycoside, macrolide, and tetracycline antibiotics. Therefore, gatifloxacin may be active against pathogens that are resistant to these antibiotics and these antibiotics may be active against pathogens that are resistant to gatifloxacin. There is no cross-resistance between gatifloxacin and the aforementioned classes of antibiotics. Cross-resistance has been observed between systemic gatifloxacin and some other fluoroquinolones.

Oseltamivir phosphate is an ethyl ester prodrug requiring ester hydrolysis for conversion to the active form, oseltamivir carboxylate. Oseltamivir carboxylate is an inhibitor of influenza virus neuraminidase affecting release of viral particles. Oseltamivir is a well tolerated orally active neuraminidase inhibitor which significantly reduces the duration of symptomatic illness and hastens the return to normal levels of activity when initiated promptly in patients with naturally acquired influenza.

Cidofovir is an antiviral nucleotide analogue with significant activity against cytomegalovirus (CMV) and other herpesviruses. Cidofovir suppresses cytomegalovirus (CMV) replication by selective inhibition of viral DNA synthesis. Biochemical data support selective inhibition of CMV DNA polymerase by cidofovir diphosphate, the active intracellular metabolite of cidofovir. Incorporation of cidofovir into the growing viral DNA chain results in reductions in the rate of viral DNA synthesis. Cidofovir is indicated for the treatment of CMV retinitis in patients with acquired immunodeficiency syndrome.

Meropenem (generic name: meropenem hydrate) is a carbapenem antibiotic for injection showing a strong antibacterial activity to a wide range of bacteria strains from Gram-positive bacteria, Gram-negative bacteria to anaerobic bacteria. It is used as single agent therapy for the treatment of the following infections: complicated skin and skin structure infections due to Staphylococcus aureus (b-lactamase and non-b-lactamase producing, methicillin-susceptible isolates only), Streptococcus pyogenes, Streptococcus agalactiae, viridans group streptococci. This drug also used in case of Intra-abdominal Infections for the treatment complicated appendicitis and peritonitis caused by viridans group streptococci, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bacteroides fragilis, B. thetaiotaomicron, and Peptostreptococcus species. In addition is used the treatment of bacterial meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae (b-lactamase and non-b-lactamase-producing isolates), and Neisseria meningitides. The bactericidal activity of meropenem results from the inhibition of cell wall synthesis. Meropenem readily penetrates the cell wall of most Gram-positive and Gram-negative bacteria to reach penicillin-binding-protein (PBP) targets. Its strongest affinities are toward PBPs 2, 3 and 4 of Escherichia coli and Pseudomonas aeruginosa; and PBPs 1, 2 and 4 of Staphylococcus aureus. Meropenem has significant stability to hydrolysis by β-lactamases, both penicillinases and cephalosporinases produced by Gram-positive and Gram-negative bacteria. Meropenem should not be used to treat methicillin-resistant Staphylococcus aureus (MRSA) or methicillin-resistant Staphylococcus epidermidis (MRSE). Meropenem product with such superior effectiveness and safety has been approved for marketing by 100 countries or more in the world (as of March 2004) since its first launch in Italy in 1994.

Levofloxacin is the L-isomer of the racemate, ofloxacin, a quinolone antimicrobial agent. Levofloxacin is used for oral and intravenous administration. Levofloxacin is sold under brand name levaquin and is used to treat infections in adults (≥18 years of age) caused by designated, susceptible bacteria such as, pneumonia: nosocomial and community acquired; skin and skin structure infections: complicated and uncomplicated; chronic bacterial prostatitis; inhalational anthrax. In addition this drug is used to treat plague; urinary tract infections: complicated and uncomplicated; acute pyelonephritis; acute bacterial exacerbation of chronic bronchitis and acute bacterial sinusitis. Levofloxacin, like other fluoroquinolones, inhibits the bacterial DNA gyrase, halting DNA replication. This results in strand breakage on a bacterial chromosome, supercoiling, and resealing. In addition, levofloxacin inhibits a bacterial type II topoisomerase.

Penciclovir (DENAVIR®) is a synthetic acyclic guanine derivative with antiviral activity, mainly used to treat infections from herpes simplex virus (HSV) types 1 and 2. In cells infected with HSV-1 or HSV-2, the viral thymidine kinase phosphorylates penciclovir to a monophosphate form that, in turn, is converted by cellular kinases to the active form penciclovir triphosphate. Biochemical studies demonstrate that penciclovir triphosphate inhibits HSV polymerase competitively with deoxyguanosine triphosphate. Consequently, herpes viral DNA synthesis and, therefore, replication are selectively inhibited. Famciclovir (FAMVIR®) is a prodrug form of penciclovir with improved oral bioavailability.

Ganciclovir is a synthetic acyclic nucleoside analogue of 2'-deoxyguanosine active against cytomegalovirus. Ganciclovir has been shown to be active against cytomegalovirus (CMV) and herpes simplex virus (HSV) in humans. To achieve anti-CMV activity, ganciclovir is phosphorylated first to the monophosphate form by a CMV-encoded (UL97 gene) protein kinase homologue, then to the di- and triphosphate forms by cellular kinases. Ganciclovir triphosphate concentrations may be 100-fold greater in CMV-infected than in uninfected cells, indicating preferential phosphorylation in infected cells. Ganciclovir triphosphate, once formed, persists for days in the CMV-infected cell. Ganciclovir triphosphate is believed to inhibit viral DNA synthesis by (1) competitive inhibition of viral DNA polymerases; and (2) incorporation into viral DNA, resulting in eventual termination of viral DNA elongation. Ganciclovir is indicated for the treatment of CMV retinitis in immunocompromised patients, including patients with acquired immunodeficiency syndrome (AIDS) and for the treatment of acute herpetic keratitis.

Cefixime, an antibiotic, is a third-generation cephalosporin like ceftriaxone and cefotaxime. Cefixime is highly stable in the presence of beta-lactamase enzymes. As a result, many organisms resistant to penicillins and some cephalosporins due to the presence of beta-lactamases, may be susceptible to cefixime. The antibacterial effect of cefixime results from inhibition of mucopeptide synthesis in the bacterial cell wall. Like all beta-lactam antibiotics, cefixime binds to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, causing the inhibition of the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that cefixime interferes with an autolysin inhibitor. Cefixime is sold under the brand name Suprax, indicated for the treatment of: Uncomplicated Urinary Tract Infections Otitis Media Pharyngitis and Tonsillitis Acute Exacerbations of Chronic Bronchitis Uncomplicated Gonorrhea (cervical/urethral)