The US National Institutes of Health (NIH) has started enrolling monkeypox patients in a late-stage study testing Siga Technologies antiviral pill Tpoxx against the disease.

The oral and intravenous formulations of Tpoxx are approved by the US Food and Drug Administration for the treatment of smallpox, but does not yet have clearance to treat monkeypox.

It is, however, currently accessible by clinicians for treating monkeypox under a compassionate use request.

The NIH aims to enroll more than 500 patients, including both adults and children, who will then be randomized to receive either Tpoxx or placebo pills for 14 days.

Investigators will evaluate if participants receiving Tpoxx heal more quickly compared to placebo, as well as provide critical data on the optimal dosing and safety of the drug in children and people who are pregnant.

The United States has recorded more than 21,000 confirmed cases of monkeypox, according to data from the Centers for Disease Control and Prevention.

Monkeypox is a rare disease caused by infection with the monkeypox virus, and is part of the same family of viruses as variola virus, the virus that causes smallpox. Its symptoms are similar to smallpox symptoms, but milder, and monkeypox is rarely fatal. 

Monkeypox was discovered in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research. Despite being named monkeypox, the source of the disease remains unknown. However, African rodents and non-human primates (like monkeys) might harbour the virus and infect people.

The first human case of monkeypox was recorded in 1970. Prior to the 2022 outbreak, monkeypox had been reported in people in several central and western African countries. Previously, almost all monkeypox cases in people outside of Africa were linked to international travel to countries where the disease commonly occurs or through imported animals. These cases occurred on multiple continents.

The US National Institutes of Health (NIH) has started enrolling monkeypox patients in a late-stage study testing Siga Technologies antiviral pill Tpoxx against the disease.

The oral and intravenous formulations of Tpoxx are approved by the US Food and Drug Administration for the treatment of smallpox, but does not yet have clearance to treat monkeypox.

It is, however, currently accessible by clinicians for treating monkeypox under a compassionate use request.

The NIH aims to enroll more than 500 patients, including both adults and children, who will then be randomised to receive either Tpoxx or placebo pills for 14 days.

Investigators will evaluate if participants receiving Tpoxx heal more quickly compared to placebo, as well as provide critical data on the optimal dosing and safety of the drug in children and people who are pregnant.

The United States has recorded more than 21,000 confirmed cases of monkeypox, according to data from the Centers for Disease Control and Prevention.

Monkeypox is a rare disease caused by infection with the monkeypox virus, and is part of the same family of viruses as variola virus, the virus that causes smallpox. Its symptoms are similar to smallpox symptoms, but milder, and monkeypox is rarely fatal. 

Monkeypox was discovered in 1958 when two outbreaks of a pox-like disease occurred in colonies of monkeys kept for research. Despite being named monkeypox, the source of the disease remains unknown. However, African rodents and non-human primates (like monkeys) might harbour the virus and infect people.

The first human case of monkeypox was recorded in 1970. Prior to the 2022 outbreak, monkeypox had been reported in people in several central and western African countries. Previously, almost all monkeypox cases in people outside of Africa were linked to international travel to countries where the disease commonly occurs or through imported animals. These cases occurred on multiple continents.