New drugs are coming to treat COVID
Whilst the world has its gaze fixed upon the latest COVID variant, new treatments are coming to the rescue in the fight against the pandemic. They herald the beginning of the end to the pandemic and the disruption to daily life.
Although the treatments are still sometime away, the data from trials is so encouraging that some of them have been stopped early. The two new drugs, Paxlovid and Molnupravir, are rapidly progressing through regulatory approval across the USA, Europe and the UK.
The new drugs are known as “small molecule” drugs. They are made from molecules which are cheap and easy to produce. Pricing is yet to be confirmed, although they will be a fraction of the cost of monoclonal antibody treatments. That means they will be accessible to many, worldwide.
The UK has already authorised the use of Molnupiravir, amongst patients most at risk from severe COVID. Those who are severely obese, over 60, have Diabetes Mellitus or heart disease can already be given the treatment. The authorisation is likely to be extended as more data becomes available.
The UK has also ordered 400,000 doses of Molnupiravir and 250,000 doses of Paxlovid, contingent upon regulatory approval. As the Paxlovid trial was ended early due to “overwhelming efficacy”, this is also likely to happen in the coming weeks.
How does Paxlovid work?
Paxlovid is a combination of two different drugs. A well-established treatment called Ritonavir has been combined with a newly designed protease inhibitor (memorably called “aspf-07321332”).
Protease is a substance which breaks down proteins and enzymes in the body. The new inhibitor is designed to block the protease
enzymes that SARS-COV-2 uses to replicate, stopping it dead in its tracks.
Because the body can process proteins and enzymes quite rapidly, Ritonavir is used to prevent the drug from being broken down too quickly in the body.
What happened during the Paxlovid trial?
Trial participants were treated with the drug within 3 days of the onset of symptoms. Initial analysis of the Phase 3 trial data showed that of 1,219 adults enrolled, the risk of COVID related hospital admission or death was reduced by a staggering 89%.
Throughout the 28 day trial monitoring period, no deaths were reported among patients who received Paxlovid, however, ten occurred in the group treated with a placebo.
How does Molnupiravir work?
Molnupiravir is a “prodrug” that becomes active only when it arrives inside cells. Once inside a cell it combines with the genetic material of the virus, disrupting its ability to replicate. Although the errors it induces are small, they cumulatively build to a point where the virus completely collapses.
Phase 1 trials posed a theoretical risk to unborn children, so the MHRA has advised against using the drug during pregnancy or breastfeeding.
The results from the Molnupiravir trial
Phase 2 trial results showed that the drug was highly effective at combating SARS-CoV-2. However, the full results of the Phase 3 trial are yet to be published. Despite this, trial data shared with regulators has resulted in emergency licences being granted. The European Medicines Agency has also recently joined the MHRA in authorising the treatment.
Although Merck indicated that the drug reduces the risk of hospitalisation or death by about 50%, data released last week indicated that the efficacy was lower. The drug was shown to deliver a relative risk reduction of death of 30%. However, even the lower efficacy is still sufficient to save many thousands of lives.
What difference will the drugs make?
The drugs really are the turning of the tide in the fight against the pandemic. Even if people become quite unwell with COVID, the drugs should keep many out of hospital. That reduces the pressure on health care systems, which means there is less need to consider restrictions on our daily activities.
Merck has reportedly stated it expects to produce 10 million doses of Molnupiravir this year and 20 million next year. Pfizer has indicated it expects 180,000 packs of pills to be produced this month, rising to 21 million packs by mid-2022.
With vaccines and other widely available treatments such as Dexamethasone, the armoury is becoming better and better equipped to fight the virus head on. Other widely available treatments, like Fluvoxamine (an antidepressant) also look as if they may substantially reduce the risks from COVID too.
A pause for breath
Although the new treatments are coming, the need for mitigations (e.g. socially responsible behaviour, distancing and hygiene) remains critically important. The virus can mutate and develop resistance, as we are all more aware.
Combining comprehensive vaccination (even if they have to be regularly tweaked, like flu vaccines) and highly effective drug treatments will create a defence that the virus will struggle to overcome.
The fight against the virus is not yet over, but with more and more tools becoming available, catching the virus will be significantly
less dangerous, even for those most at risk.
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