Maribavir (previously known as 1263W94) is a novel benzimidazole riboside compound. This drug was in phase III of clinical trial for the prevention of cytomegalovirus (CMV) infections in transplant patients, sponsored by ViroPharma. However, drug failed to demonstrate a higher efficacy rate than the placebo. Maribavir has activity against cytomegalovirus and Epstein-Barr virus (EBV), but not against other human herpesviruses. Maribavir’s mechanism of action is unique and is complex compared to the currently approved antivirals for CMV. Maribavir inhibits the viral UL97 kinase rather than the viral DNA polymerase. The UL97 kinase is important for viral DNA elongation, DNA packaging, and nuclear egress of encapsidated viral DNA. In addition, maribavir inhibits the EBV DNA polymerase processivity factor (BMRF1), reduces the level of certain EBV glycoproteins, and inhibits viral transcription. However, future work will be designed to address the interaction of MBV and BGLF4 and to evaluate the mechanisms through which maribavir downregulates viral transcripts. BGLF4 belongs to the family of conserved herpesvirus PKs, which includes HCMV UL97, HSV UL13, and HSV US3. Maribavir does need to be phosphorylated for its activity.

Doravirine (MK-1439) is a nonnucleoside inhibitor of HIV reverse transcriptase (NNRTI). It displays excellent activities against not only WT viruses but also a broader panel of NNRTI-resistant viruses. Doravirine is a prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the treatment of HIV infection in adults who have never taken HIV medicines before. Doravirine is always used in combination with other HIV medicines.

Bictegravir is a component of the fixed-dose combination product bictegravir/emtricitabine/tenofovir alafenamide (BIKTARVY®), which received marketing approval for the treatment of human immunodeficiency virus (HIV) infection by the U.S. Food and Drug Administration in February 2018. Bictegravir inhibits the strand transfer activity of HIV-1 integrase, an HIV-1 encoded enzyme that is required for viral replication. Inhibition of integrase prevents the integration of linear HIV-1 DNA into host genomic DNA, blocking the formation of the HIV-1 provirus and propagation of the virus.

Eravacycline, known as Xerava by Tetraphase Pharmaceuticals, is a fully synthetic fluorocycline antibiotic of the tetracycline class with activity against clinically significant gram-negative, gram-positive aerobic, and facultative bacteria. This includes most of those bacteria resistant to cephalosporins, fluoroquinolones, β-lactam/β-lactamase inhibitors, multidrug-resistant strains, and carbapenem-resistant Enterobacteriaceae, and the majority of anaerobic pathogens. It was first approved by the FDA on August 27, 2018. Eravacycline disrupts bacterial protein synthesis by binding to the 30S ribosomal subunit thus preventing the incorporation of amino acid residues into elongating peptide chains.

Delafloxacin (CAS registry number 189279-58-1) was described as WQ-3034 by Wakunaga Pharmaceutical Co., Ltd., Osaka & Hiroshima, Japan. It was first licensed in 1999 to Abbott Park, IL, and further developed as ABT-492. Delafloxacin (Baxdela), a fluoroquinolone antibiotic, is currently being developed by Melinta Therapeutics. It is a novel investigational fluoroquinolone in development for the treatment of uncomplicated gonorrhea, and acute bacterial skin and skin structure infections. Delafloxacin shows MICs remarkably low against Gram-positive organisms and anaerobes and similar to those of ciprofloxacin against Gram-negative bacteria. It remains active against most fluoroquinolone-resistant strains, except enterococci. Its potency is further increased in acidic environments (found in many infection sites). Delafloxacin is active on staphylococci growing intracellularly or in biofilms. Delafloxacin is a dual-targeting fluoroquinolone, capable of forming cleavable complexes with DNA and topoisomerase IV or DNA gyrase and of inhibiting the activity of these enzymes in both Gram-positive and Gram-negative bacteria. On Oct 24, 2016, Melinta Therapeutics Submitted Baxdela New Drug Application for hospital-treated skin infections.

Voxilaprevir is a Direct-Acting Antiviral (DAA) medication used as part of combination therapy to treat chronic Hepatitis C, an infectious liver disease caused by infection with Hepatitis C Virus (HCV). Sofosbuvir/velpatasvir/voxilaprevir (Vosevi) is indicated for adult patients with chronic HCV without cirrhosis or with compensated cirrhosis who have (1) genotype 1 through 6 and have previously been treated with an NS5A inhibitor or (2) genotype 1a or 3 and have previously been treated with sofosbuvir without an NS5A inhibitor. Voxilaprevir exerts its antiviral action by reversibley binding and inhibiting the NS3/4A serine protease of Hepatitis C Virus (HCV). Following viral replication of HCV genetic material and translation into a single polypeptide, Nonstructural Protein 3 (NS3) and its activating cofactor Nonstructural Protein 4A (NS4A) are responsible for cleaving genetic material into the following structural and nonstructural proteins required for assembly into mature virus: NS3, NS4A, NS4B, NS5A, and NS5B. By inhibiting viral protease NS3/4A, voxilaprevir therefore prevents viral replication and function.

Pibrentasvir is a direct acting antiviral agent and Hepatitis C virus (HCV) NS5A inhibitor that targets the the viral RNA replication and viron assembly. NS5A is a phosphoprotein that plays an essential role in replication, assembly and maturation of infectious viral proteins. The basal phosphorylated form of NS5A, which is maintained by C-terminal serine cluster, is key in ensuring its interaction with the viral capsid protein, or the core protein. By blocking this interaction, pibrentasvir inhibits the assembly of proteins and production of mature HCV particles. In the United States and Europe, Pibrentasvir is approved for use with glecaprevir as the combination drug glecaprevir/pibrentasvir (trade name Mavyret in the US and Maviret in the EU) for the treatment of hepatitis C. This fixed-dose combination therapy was FDA-approved in August 2017 to treat adults with chronic hepatitis C virus (HCV) genotypes 1-6 without cirrhosis (liver disease) or with mild cirrhosis, including patients with moderate to severe kidney disease and those who are on dialysis.

Glecaprevir is a direct acting antiviral agent and Hepatitis C virus (HCV) NS3/4A protease inhibitor that targets the the viral RNA replication. In combination with Pibrentasvir, glecaprevir is a useful therapy for patients who experienced therapeutic failure from other NS3/4A protease inhibitors. It demonstrates a high genetic barrier against resistance mutations of the virus. Glecaprevir is available as an oral combination therapy with Pibrentasvir under the brand name Mavyret. On 3 August 2017 the FDA approved the combination for hepatitis C treatment. Mavyret is indicated for the treatment of adult patients with chronic hepatitis C virus (HCV) genotype 1, 2, 3, 4, 5 or 6 infection without cirrhosis or with compensated cirrhosis (Child-Pugh A). Mavyret is also indicated for the treatment of adult patients with HCV genotype 1 infection, who previously have been treated with a regimen containing an HCV NS5A inhibitor or an NS3/4A protease inhibitor (PI), but not both.

Vaborbactam (formerly RPX7009) is a new beta-lactamase inhibitor based on a cyclic boronic acid pharmacophore. Vaborbactam is a highly active beta-lactamase inhibitor that restores activity of meropenem and other beta-lactam antibiotics in beta-lactamase-producing bacteria, particularly KPC-producing CRE. Meropenem in combination with vaborbactam (VABOMERE) is indicated for the treatment of patients 18 years and older with complicated urinary tract infections including pyelonephritis caused by designated susceptible bacteria. The vaborbactam component of VABOMERE is a non-suicidal beta-lactamase inhibitor that protects meropenem from degradation by certain serine beta-lactamases such as Klebsiella pneumoniae carbapenemase (KPC). Vaborbactam does not have any antibacterial activity. Vaborbactam does not decrease the activity of meropenem against meropenem-susceptible organisms.

Letermovir (AIC246 or MK-8228), a 3,4-dihydro-quinazoline- 4-yl-acetic acid derivative, is the prototype viral terminase complex inhibitor that is most advanced in its clinical development. The novel compound was initially developed by AiCuris. In April 2011, the drug was granted orphan drug designation for prevention of CMV disease by the European Commission. In August 2011, the US Food and Drug Administration granted it a fast track designation. In 2012, the results of Phase IIb clinical trials using letermovir in bone marrow transplant patients were presented at various international meetings, and the data were subsequently published in 2014.42 It`s continued clinical development is currently undertaken in agreement with Merck. Letermovir is highly potent in vitro and in vivo against cytomegalovirus. Because of a distinct mechanism of action, it does not exhibit cross-resistance with other antiviral drugs. It is predicted to be active against strains that are resistant to ganciclovir, foscarnet, and cidofovir. To date, early-phase clinical trials suggest a very low incidence of adverse effects. It targets the UL56 subunit of the viral terminase complex. Letermovir is currently in Phase III development.