Skripal and his daughter may have overdosed on Fentanyl.
Summary
Slow deaths are good for news stories. Just as Litvinenko was being slowly poisoned with weak poison, this comrade [Skripal] is being slowly poisoned with weak poison to prolong Western news coverage.
Disproof
No evidence given. Russophobia is often used in pro-Kremlin disinformation as an explanation for anyone blaming Russia for anything euvsdisinfo.eu/the-russophobia-myth-appealing-to-the-lowest-feelings/, .
Many competing and contradictory stories promulgated by Russian state-controlled media. euvsdisinfo.eu/disinformation-cases/?text=sergei+skripal&disinfo_issue=&date=,
The nerve agent has been identified as Novichok (which means newcomer in Russian). It is known to be more powerful than VX and was developed in the Soviet Union in the 1970s and 1980s https://www.voanews.com/a/british-prime-minister-russia-poisoning-spy/4294683.html. It's so unusual, that very few scientists outside of Russia have any real experience in dealing with it and no country outside of Russia is known to have developed the substance https://edition.cnn.com/2018/03/13/europe/what-is-novichok-nerve-agent-intl/index.html
British Prime Minister Theresa May said Monday a “military-grade nerve agent” known to have been developed by Russia was used to poison former Russian spy Sergei Skripal and that her government has concluded it is “highly likely” Moscow was responsible.
“Either this was a direct act by the Russian state against our country or the Russian government lost control of this catastrophically damaging nerve agent and allowed it to get into the hands of others,” she said.
Further debunking by Julia Davis twitter.com/JuliaDavisNews/status/971924556423356416, .