The boy has a litany of illnesses including cerebral palsy and epileptic seizures (Representational)

A mother of an incurably ill six-year-old boy faces up to eight years in prison in Russia for trying to sell anti-seizure medication she bought for her child, she and charities said on Wednesday.

The case -- the first of its kind in the country -- has horrified Russian charity workers and activists who deal with heart-wrenching cases on a daily bases.

Last month police opened a criminal case into the distribution of narcotics after Moscow mum-of-two Yekaterina Konnova bought diazepam rectal gel -- which is not available in Russia legally -- to treat her son Arseny's seizures.

Diazepam is a prescription medication used to treat seizures and anxiety and is available in various forms including in ampules and rectal gel tubes.

While the medication in ampules is registered in Russia, gel tubes -- which are more convenient to administer and cause no pain -- are not, unlike in the West, where they are widely used.

Most modern anti-epileptic drugs for children are not registered in Russia, forcing parents to buy them abroad or purchase them illegally on the black market.

Moscow police staged a sting operation and detained Konnova, a single mum, when she tried to sell several tubes she no longer needed.

"It's been hell," Konnova told AFP, adding her son needed to be medicated all the time and that she could not afford the expensive drugs.

"Arseny suffers pain 24/7," she said.

The boy has a litany of illnesses including cerebral palsy and epileptic seizures.

"He's got a tube in his stomach, a tube in his neck and he also suffers from terrible seizures, many times a day, every day," wrote Lida Moniava, deputy director at the Lighthouse, a children's hospice in Moscow.

"We are horrified by what's happening because if Katya goes to prison Aseny will end up in a care home for the disabled where he will quickly die and his elder brother will go to an orphanage," she said on Facebook.

Konnova faces between four and eight years in prison for drug dealing, charities said.

Nyuta Federmesser, a hugely respected public figure who supports Russian hospices, called on President Vladimir Putin to intervene and change legislation to help alleviate the suffering of young patients and their families.

"We are developing nanotechnology, we can organise the World Cup and host Olympic Games, we fly to space, we develop gene engineering, we have crypto currencies and blockchain," she wrote in an appeal on Facebook.

"Cannot we change legislation???"

Russia's healthcare system is largely antiquated and many state-of-the-art surgeries are not performed in the country.

Seeking to crack down on drug trafficking, the authorities have created a deficit of opioid painkillers for terminally ill people.

Thousands of cancer patients die in agony each year and some commit suicide, unable to endure pain.