Since the onset
of the COVID-19 pandemic in 2020, researchers have been continuously striving
towards developing effective therapies to contain the virus and minimize its
implications on the affected individuals. While wearing masks,
social-distancing, sanitization, and vaccination remained the leading options
for preventing the transmission of infections, the upsurge in the latest
coronavirus mutation, Omicron variant, has created an urgent necessity for
antiviral therapies that reduce the risk of coronavirus progression.
The United
States Food and Drug Administration (USFDA) has granted authorization of two
COVID-19 pills, NIRMATRELVIR (branded as PAXLOVID) by Pfizer and MOLNUPIRAVIR
by Merck and Ridgeback Biotherapeutics for high-risk people. Both the pills
have the ability to reduce the viral load by more than tenfold and
significantly reduce contagiousness to others.
The new
antiviral pills are designed to work against the coronavirus
and its variants, reducing the need for hospitalizations and mortality rates.
Currently, health authorities are providing antiviral pills to individuals with
mild or moderate COVID or who have a high risk of serious illness due to
chronic issues like diabetes, cardiovascular disorders, compromised immune
functioning, etc.
The antiviral
pills are required to be taken home as soon as possible, within five days of
the start of the symptoms. Fever, cold, headache, loss of taste or smell,
muscle and body aches are some of the common symptoms that people are
experiencing with the new coronavirus variant. Starting the pills in a short
window is the real challenge due to delay in testing and getting a
prescription.
Mechanism of
Paxlovid Against COVID-19 Infection
Paxloid drug is
designed to slow the spread of infection by disrupting specific processes in
the viral assembly, choking the virus’s ability to replicate and cause damage.
The antiviral medication has a cellular component called a protease that cuts
virus’s polyprotein, a large, clumped mass generated by replicating the action
of coronavirus for survival, into small and workable pieces. Paxlovid is a
combination of two antiviral drugs, nirmatrelvir, a novel main
protease inhibitor that cuts viral products into smaller pieces, and ritonavir,
which enables nirmatrelvir to remain active in the body for more extended
periods at higher concentrations.
Thus, the
anti-COVID pill can be considered a huge advancement for all kinds of
coronaviruses since it reduces the chances of the virus developing resistance.
In clinical trials, Paxlovid showed an 89% reduction in hospitalization or
death in those who received treatment within just three days of symptom onset.
Hence, the authorization of Paxlovid prevents disease progression and reduces
the burden on hospitals. Since nirmatrelvir has previously shown efficacy
against variants of concerns like alpha, beta, gamma, lambda, and mu, it has
the potential to maintain robust antiviral action against omicron.
Some of the
side-effects of taking the treatment are altered sense of taste, diarrhea, high
blood pressure and muscle aches. Individuals who have any allergies, liver or
kidney disease, pregnant or breastfeeding a child or any serious illnesses must
refrain from taking the medication.
Mechanism of
Molnupiravir Against COVID-19 Infection
Molnupiravir is
a polymerase inhibitor that increases the frequency of viral RNA mutations and
impairs coronavirus replication. SARS-CoV-1 and SARS-CoV-2 use an RNA-dependent
RNA polymerase (RdRp), a cellular component that works like a photocopying
machine for the reproduction and transcription of their RNA genome. Most
antiviral drugs can target viral polymerase to terminate RNA chain elongation
of the virus, but SARS-CoV-2 carries an exonucleolytic that remove
misincorporated nucleotides.
However,
Molnupiravir is turning out to be a promising treatment since it can target the
RdRp of SARS-CoV-2 like the previously approved drug, Remdesivir. The oral
medication acts as a mutageninzing agent that inserts itself into the viral
instructions, which RdRp is copying to proliferate. Thus, causing an ‘error
catastrophe’ during viral replication, Molnupiravir inhibits the virus from
replicating further. Molnupiravir can trigger mutations in other RNA viruses
and thus treat a range of viral diseases. Earlier the oral medication was used
to treat influenza and now in clinical studies, it is found to be highly
effective against SARS-CoV-2.
The anti-viral
COVID pill is highly effective in reducing the incidence of hospitalization or
deaths related to infection. Some of the side effects of Molnupiravir include
nausea, dizziness, diarrhea, and headache. Individuals less than 18 years or
hospitalized patients with severe symptoms should not take Molnupiravir.
Molnupravir’s mechanism of action against COVID-19 could induce viral mutations,
which could form mutations within human DNA, whereas Paxloid has shown no signs
of mutagenic DNA interactions. Also,
these anti-COVID pills are substitutes for the vaccines; thus, one must take
proper measures and get vaccinated to prevent infection.
How
Anti-Covid Pills Differ from Vaccines?
Unlike vaccines,
the antiviral pills are not a preventive strategy. Rather, they treat an
infected person with the symptoms arising from the viral infection. Vaccines
stimulate the production of antibodies to strengthen the body’s defense system
against the infection. To do so, vaccines put the immune system through a
‘’rehearsal’’ mode before it has to really fight off the real coronavirus. In
our bodies, DNA is the nucleus that instructs the rest of the cells what
proteins to build via a molecule called messenger RNA (mRNA).