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Routes of administration | Oral, intranasal |
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Pharmacokinetic data | |
Bioavailability | 70% (oral) |
Protein binding | >99% |
Metabolism | Hepatic |
Excretion | <1% excreted unchanged in urine |
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PDB ligand | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.208.947 |
Chemical and physical data | |
Formula | C18H18F3N3O3 |
Molar mass | 381.355 g·mol−1 |
3D model (JSmol) | |
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Pleconaril (Picovir [1] ) is an antiviral drug that was being developed by Schering-Plough for prevention of asthma exacerbations and common cold symptoms in patients exposed to picornavirus respiratory infections. [2] Pleconaril, administered either orally or intranasally, is active against viruses in the Picornaviridae family, including Enterovirus [3] and Rhinovirus . [4] It has shown useful activity against the dangerous enterovirus D68. [5]
Pleconaril was originally developed by Sanofi-Aventis, and licensed to ViroPharma in 1997. ViroPharma developed it further, and submitted a New Drug Application to the United States Food and Drug Administration (FDA) in 2001. The application was rejected, citing safety concerns; and ViroPharma re-licensed it to Schering-Plough in 2003. The Phase II clinical trial was completed in 2007. [2] A pleconaril intranasal spray had reached phase II clinical trial for the treatment of the common cold symptoms and asthma complications. However, the results have yet to be reported. [6]
In enteroviruses, pleconaril prevents the virus from exposing its RNA, and in rhinoviruses pleconaril prevents the virus from attaching itself to the host cell. [7] Human rhinoviruses (HRVs) contain four structural proteins labeled VP1-VP4. Proteins VP1, VP2 and VP3 are eight stranded anti-parallel β-barrels. VP4 is an extended polypeptide chain on the viral capsid inner surface. [8] Pleconaril binds to a hydrophobic pocket in the VP1 protein. Pleconaril has been shown in viral assembly to associate with viral particles. [9] Through noncovalent, hydrophobic interactions compounds can bind to the hydrophobic pocket. [10] Amino acids in positions Tyr152 and Val191 are a part of the VP1 drug binding pocket. [8]
In Coxsackievirus, pleconaril efficiency correlates to the susceptibility of CVB3 with the amino acid at position 1092 in the hydrophobic pocket. [11] Amino acid 1092 is in close proximity to the central ring of capsid binders. [12] The binding of pleconaril in the hydrophobic pocket creates conformational changes, which increases the rigidity of the virion and decreases the virions' ability to interact with its receptor. [13] Drugs bind with the methylisoxazole ring close to the entrance pocket in VP1, the 3-fluromethyl oxadiazole ring at the end of the pocket and the phenyl ring in the center of the pocket. [6]
The results of two randomized, double blind, placebo studies found Pleconaril treatment could benefit patients with colds due to picornaviruses. [14] Participants in the studies were healthy adults from Canada and the United States, with self-diagnosed colds that had occurred within 24 hours of trial enrollment. Participants were randomly given a placebo or two 200 mg tablets to take three times daily for five days. To increase absorption it was recommended to be taken after a meal. [14] To monitor the effectiveness of Pleconaril, participants recorded the severity of their symptoms and nasal mucosal samples were obtained at enrollment, day 3, day 6 and day 18. The two studies had a total of 2096 participants and more than 90% (1945) completed the trial. The most common reason for a participant not finishing the trial was an adverse event. Pleconaril treatment showed a reduction in nose blowing, sleep disturbance, and less cold medication used. [14]
Another study showed over 87% of virus isolates in cell culture were inhibited by pleconaril. [9] Virus variants were detected in 0.7% of the placebo group and 10.7% of the pleconaril group. Of the two isolates a subject from the placebo group had a resistant virus in cell culture to pleconaril. The other strain was susceptible to the drug. The pleconaril group had 21 virus strains, which remained susceptible. Resistance strains were found in 7 pleconaril patients. [9]
A Phase II study that used an intranasal formulation of pleconaril failed to show a statistically significant result for either of its two primary efficacy endpoints, percentage of participants with rhinovirus PCR-positive colds and percentage of participants with asthma exacerbations together with rhinovirus-positive PCR. [2]
In human rhinoviruses mutations in amino acids at positions 152 and 191 decrease the efficiency of pleconaril. The resistant HRV have phenylalanine at position 152 and leucine at position 191. In vitro studies have shown resistance to pleconaril may emerge. The wild type resistance frequency to pleconaril was about 5×10−5. Coxsackievirus B3 (CVB3) strain Nancy and other mutants carry amino acid substitutions at position 1092 of Ile1092->Leu1092 or Ile1092->Met in VP1. The Ile->Leu mutation causes complete resistance to pleconaril. The study found resistance of CVB3 to pleconaril can be overcome by substitution of the central phenyl group. Methyl and bromine substitutions created an increase of pleconaril activity towards sensitive and resistant strains. Amino acid substitutions in the hydrophobic pocket and receptor binding region of viral capsid proteins were shown to have an effect against the sensitivity of capsid binding antivirals. [6]
The U.S. Food and Drug Administration rejected pleconaril in 2002 due to the side effects. The most commonly reported side effects were mild to moderate headache, diarrhea, and nausea. [14] Some women were having symptoms of spotting in between periods. Menstrual irregularities were reported by 3.5% of the 320 pleconaril treated women using oral contraceptives and by none of the 291 placebo treated women. [14] In the clinical trial two women became pregnant due to the drug interfering with hormonal birth control by activation of cytochrome P-450 3A enzymes. Other patients have described painful nasal inflammation. [15]
Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Antiviral drugs are one class of antimicrobials, a larger group which also includes antibiotic, antifungal and antiparasitic drugs, or antiviral drugs based on monoclonal antibodies. Most antivirals are considered relatively harmless to the host, and therefore can be used to treat infections. They should be distinguished from virucides, which are not medication but deactivate or destroy virus particles, either inside or outside the body. Natural virucides are produced by some plants such as eucalyptus and Australian tea trees.
The common cold or the cold is a viral infectious disease of the upper respiratory tract that primarily affects the respiratory mucosa of the nose, throat, sinuses, and larynx. Signs and symptoms may appear fewer than two days after exposure to the virus. These may include coughing, sore throat, runny nose, sneezing, headache, and fever. People usually recover in seven to ten days, but some symptoms may last up to three weeks. Occasionally, those with other health problems may develop pneumonia.
The rhinovirus is the most common viral infectious agent in humans and is the predominant cause of the common cold. Rhinovirus infection proliferates in temperatures of 33–35 °C (91–95 °F), the temperatures found in the nose. Rhinoviruses belong to the genus Enterovirus in the family Picornaviridae.
Coxsackie B4 virus are enteroviruses that belong to the Picornaviridae family. These viruses can be found worldwide. They are positive-sense, single-stranded, non-enveloped RNA viruses with icosahedral geometry. Coxsackieviruses have two groups, A and B, each associated with different diseases. Coxsackievirus group A is known for causing hand-foot-and-mouth diseases while Group B, which contains six serotypes, can cause a varying range of symptoms like gastrointestinal distress myocarditis. Coxsackievirus B4 has a cell tropism for natural killer cells and pancreatic islet cells. Infection can lead to beta cell apoptosis which increases the risk of insulitis.
Coxsackie B is a group of six serotypes of coxsackievirus (CVB1-CVB6), a pathogenic enterovirus, that trigger illness ranging from gastrointestinal distress to full-fledged pericarditis and myocarditis.
Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm icosahedral capsid. The viruses in this family can cause a range of diseases including the common cold, poliomyelitis, meningitis, hepatitis, and paralysis.
Zanamivir is a medication used to treat and prevent influenza caused by influenza A and influenza B viruses. It is a neuraminidase inhibitor and was developed by the Australian biotech firm Biota Holdings. It was licensed to Glaxo in 1990 and approved in the US in 1999, only for use as a treatment for influenza. In 2006, it was approved for prevention of influenza A and B. Zanamivir was the first neuraminidase inhibitor commercially developed. It is marketed by GlaxoSmithKline under the trade name Relenza as a powder for oral inhalation.
Enterovirus is a genus of positive-sense single-stranded RNA viruses associated with several human and mammalian diseases. Enteroviruses are named by their transmission-route through the intestine.
ViroPharma Incorporated was a pharmaceutical company that developed and sold drugs that addressed serious diseases treated by physician specialists and in hospital settings. The company focused on product development activities on viruses and human disease, including those caused by cytomegalovirus (CMV) and hepatitis C virus (HCV) infections. It was purchased by Shire in 2013, with Shire paying around $4.2 billion for the company in a deal that was finalized in January 2014. ViroPharma was a member of the NASDAQ Biotechnology Index and the S&P 600.
A resistance mutation is a mutation in a virus gene that allows the virus to become resistant to treatment with a particular antiviral drug. The term was first used in the management of HIV, the first virus in which genome sequencing was routinely used to look for drug resistance. At the time of infection, a virus will infect and begin to replicate within a preliminary cell. As subsequent cells are infected, random mutations will occur in the viral genome. When these mutations begin to accumulate, antiviral methods will kill the wild type strain, but will not be able to kill one or many mutated forms of the original virus. At this point a resistance mutation has occurred because the new strain of virus is now resistant to the antiviral treatment that would have killed the original virus. Resistance mutations are evident and widely studied in HIV due to its high rate of mutation and prevalence in the general population. Resistance mutation is now studied in bacteriology and parasitology.
Enterovirus E is a picornavirus of the genus Enterovirus. The virus may also be referred to as enteric cytopathic bovine orphan virus (ECBO). It is endemic in cattle populations worldwide, and although normally fairly nonpathogenic, it can cause reproductive, respiratory, or enteric disease – particularly when the animal is concurrently infected with another pathogen.
CCR5 receptor antagonists are a class of small molecules that antagonize the CCR5 receptor. The C-C motif chemokine receptor CCR5 is involved in the process by which HIV, the virus that causes AIDS, enters cells. Hence antagonists of this receptor are entry inhibitors and have potential therapeutic applications in the treatment of HIV infections.
Non-nucleoside reverse-transcriptase inhibitors (NNRTIs) are antiretroviral drugs used in the treatment of human immunodeficiency virus (HIV). NNRTIs inhibit reverse transcriptase (RT), an enzyme that controls the replication of the genetic material of HIV. RT is one of the most popular targets in the field of antiretroviral drug development.
The first human immunodeficiency virus (HIV) case was reported in the United States in the early 1980s. Many drugs have been discovered to treat the disease but mutations in the virus and resistance to the drugs make development difficult. Integrase is a viral enzyme that integrates retroviral DNA into the host cell genome. Integrase inhibitors are a new class of drugs used in the treatment of HIV. The first integrase inhibitor, raltegravir, was approved in 2007 and other drugs were in clinical trials in 2011.
sCAR-Fc is an experimental prophylactic treatment against coxsackievirus B3 (CVB) infections. Coxsackievirus B3 can cause cardiac damage, eventually resulting in a weakened and enlarged heart that is termed dilated cardiomyopathy. While many other treatments inhibit viral proliferation in myocytes, sCAR-Fc prevents the virus entering the cell by competitively binding to coxsackie virus and adenovirus receptors (CAR) on the membrane of myocytes.
Chronic Mycoplasma pneumonia and Chlamydia pneumonia infections are associated with the onset and exacerbation of asthma. These microbial infections result in chronic lower airway inflammation, impaired mucociliary clearance, an increase in mucous production and eventually asthma. Furthermore, children who experience severe viral respiratory infections early in life have a high possibility of having asthma later in their childhood. These viral respiratory infections are mostly caused by respiratory syncytial virus (RSV) and human rhinovirus (HRV). Although RSV infections increase the risk of asthma in early childhood, the association between asthma and RSV decreases with increasing age. HRV on the other hand is an important cause of bronchiolitis and is strongly associated with asthma development. In children and adults with established asthma, viral upper respiratory tract infections (URIs), especially HRVs infections, can produce acute exacerbations of asthma. Thus, Chlamydia pneumoniae, Mycoplasma pneumoniae and human rhinoviruses are microbes that play a major role in non-atopic asthma.
Picornain 3C is a protease found in picornaviruses, which cleaves peptide bonds of non-terminal sequences. Picornain 3C’s endopeptidase activity is primarily responsible for the catalytic process of selectively cleaving Gln-Gly bonds in the polyprotein of poliovirus and with substitution of Glu for Gln, and Ser or Thr for Gly in other picornaviruses. Picornain 3C are cysteine proteases related by amino acid sequence to trypsin-like serine proteases. Picornain 3C is encoded by enteroviruses, rhinoviruses, aphtoviruses and cardioviruses. These genera of picoviruses cause a wide range of infections in humans and mammals.
Enterovirus D68 (EV-D68) is a member of the Picornaviridae family, an enterovirus. First isolated in California in 1962 and once considered rare, it has been on a worldwide upswing in the 21st century. It is suspected of causing a polio-like disorder called acute flaccid myelitis (AFM).
Baloxavir marboxil, sold under the brand name Xofluza, is an antiviral medication for treatment of influenza A and influenza B. It was approved for medical use both in Japan and in the United States in 2018, and is taken as a single dose by mouth. It may reduce the duration of flu symptoms by about a day, but is prone to selection of resistant mutants that render it ineffectual.
Nirmatrelvir is an antiviral medication developed by Pfizer which acts as an orally active 3C-like protease inhibitor. It is part of a nirmatrelvir/ritonavir combination used to treat COVID-19 and sold under the brand name Paxlovid.