As the COVID-19 pandemic continues, the pharmaceuticals industry is hard at work developing targeted antivirals that can be delivered in capsule form. Clinical trials are currently underway. The goal: Develop an oral treatment regimen that can be prescribed as soon as a patient tests positive for COVID-19 and then taken at home.
To be clear, these pharmaceuticals are not meant as a substitute for vaccination. But the reality is, in spite of widespread availability of vaccine, some people either refuse or cannot get the vaccine, and, although not common, “break-through” COVID-19 cases are happening in fully-vaccinated people. Clearly there is a need for more treatment options.
Three drugs to watch
There are currently three drugs under development that are garnering the most attention:
- Molnupiravir, from Merck & Co. and Ridgeback Biotherapeutics. Based on clinical trial results, molnupiravir is the first oral antiviral that has been found to be effective against COVID-19, reducing the risk of hospitalization and death by about 50%. In december 2021, FDA granted emergency authorization to this capsule under special conditions.
Molnupiravir, which was only tested on unvaccinated people who had mild to moderate cases of COVID-19 and had at least one risk factor for developing a severe case of the disease, also appears to be effective against COVID-19 variants such as Delta and Mu. - PF-07321332, from Pfizer, which is being tested in combination with a low dose of ritonavir, another antiviral. It is believed that co-administration with ritonavir will enable PF-07321332 to remain in the body combatting the coronavirus for a longer period of time.
- AT-527, from Roche and Atea Pharmaceuticals. The latest news on this drug is that Phase 3 clinical trials have been delayed until the second half of 2022 due to disappointing Phase 2 clinical trial One possible explanation might be the design of the clinical trial itself, which included people who had been vaccinated against COVID-19.
How these antivirals work
Antivirals in general are not new. In fact, they are already being used against many viruses, including herpes, HIV, Ebola and the common flu.
Antivirals work by suppressing or interfering with the virus’ ability to replicate in human cells. Normally, as a virus multiplies the person gets increasingly ill. Disrupting this ability to multiple will in effect kill the virus.
In the case of these COVID-19 antivirals, Molnupiravir works by introducing RNA-like building blocks into the virus’ RNA genome that cause defects (i.e., “mutations”) when the cells attempt to replicate. Pfizer’s drug is a protease inhibitor designed to block the activity of the main protease enzyme that COVID-19 needs to replicate. AT-527 is designed to interfere with the virus’ RNA polymerase, which is a key component in the virus’ replication machinery.
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Having a COVID-19 treatment in capsule form can be a game changer
As of this writing, all of the antivirals approved for treating COVID-19, including Gilead Sciences’ Veklury (remdesivir) and the monoclonal antibodies, must be administered intravenously in a medical setting. Consequently, none of these existing treatments are meant for early, widespread use or for people with mild or moderate symptoms.
In contrast, the oral antivirals under development are specifically meant for early, widespread use. They are designed to:
- Reduce hospitalizations and deaths – This, of course, is the biggest benefit.
- Provide treatment at home – These oral antivirals are all home-based
- Reduce the cost of treatment current IV-based options – For example, if molnupiravir receives either emergency use or full approval, the Biden administration has agreed to purchase 1.7 million treatment courses at $700 each. In comparison, monoclonal antibody treatment costs $1,250 to $2,100 per infusion, excluding treatment fees charged by the infusion center.
- Reduce the spread of disease – In September Pfizer also began a clinical trial testing to see if PF-07321332 can prevent healthy adults who live in the same household as someone with a confirmed symptomatic COVID-19 infection from getting ill.
- Use existing pharmacy networks – Treatment can be made easily available via prescription. With no need for temperature controls or other special measures, capsules are easy to transport and dispense.
Conclusion
These are very positive and exciting developments in the on-going battle against the COVID-19 pandemic…and excellent examples of the value and benefits of capsules as a convenient, easy-to-distribute dosage form.
