Singapore approves its first oral tablet to treat Covid-19 infection

THE Health Sciences Authority (HSA), in consultation with its Medicines Advisory Committee, has on Jan 31 granted interim authorisation for Pfizer's Paxlovid.

This is the first oral tablet approved in Singapore to treat mild to moderate Covid-19 in adult patients who are at high risk of progression to severe disease.

It is intended to reduce the risk of hospitalisation and death, HSA said in a press statement on Thursday (Feb 3).

Paxlovid will be prescribed and prioritised to those at higher risk of severe Covid-19 illness, as directed by the Ministry of Health.

It is to be taken twice daily for 5 days, and the treatment should be initiated as soon as possible after a diagnosis has been made, within 5 days of the onset of Covid-19 symptoms.

Paxlovid is a combination of 2 medicines: nirmatrelvir, an antiviral medicine, and ritonavir, which maintains the blood level of nirmatrelvir for antiviral efficacy.

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HSA had granted the interim authorisation under the Pandemic Special Access Route, and in consultation with its Medicines Advisory Committee.

The authority said: "Based on the available clinical evidence, the benefits of Paxlovid outweigh the risks, and there is a favourable benefit-risk profile for the treatment of mild to moderate Covid-19 in adults who are at high risk of progression to severe Covid-19."

Paxlovid reduced the risk of Covid-19 related hospitalisation or death by 88.9 per cent, as compared to the placebo group, when treatment was given within 3 days of the onset of symptoms. This was according to HSA's review of available clinical data based on rolling submission of the results from an ongoing Phase II/III study.

The review also found that the oral tablet reduced the risk of Covid-19 related hospitalisation or death by 87.8 per cent when given within 5 days of the onset of symptoms.

The efficacy analysis included patients infected with the Delta variant. HSA noted that in vitro data has shown that Paxlovid is active against the prevailing variants of concern, including Delta and Omicron.

The randomised study recruited more than 2,000 participants, aged 18 to 88 years, with mild to moderate Covid-19, and who had 1 or more risk factors for progression to severe Covid-19.

HSA said: "The safety data showed that Paxlovid is well-tolerated. The incidences of adverse events reported in the clinical study were generally low."

The common adverse events reported were mild to moderate. They included an altered sense of taste, diarrhoea, vomiting, hypertension, muscle pain and chills.

Paxlovid may interact with some medications, such as medicines for irregular heart rate, migraine and cholesterol. It could increase the amount of these medications in the blood, leading to serious adverse events.

On the other hand, some medicines, such as those for epileptic seizures, could reduce the levels of Paxlovid and thus result in a loss of antiviral efficacy.

"The potential for drug interactions should be carefully considered by the prescribing doctor prior to treatment initiation," HSA noted.

In a separate press statement on Thursday, Pfizer Singapore country manager Erika Pagani said that oral therapies such as protease inhibitors may help to reduce the severity or onset of illness in patients who contract Covid-19.

"An oral treatment option may thus be an important tool to help address the ongoing global impact of the Covid-19 pandemic," she added.

Pfizer is required to collect safety data and monitor the use of Paxlovid, as a condition for interim authorisation under the Pandemic Special Access Route.

HSA will also require the company to continue submitting updated data from ongoing clinical studies, to ensure the continued safety and efficacy of the oral tablet, for the authority's continual benefit-risk assessment.

The interim authorisation may be terminated at any time; for example, if new data suggests that the benefits no longer outweigh the risks.

Singapore recorded 3,101 new Covid-19 cases as at noon on Wednesday. The total number hospitalised stood at 819, an increase of 63 from the previous day. Of these, 74 patients required oxygen support and 12 were in the intensive care unit.