Never in human history has a drug suddenly killed everyone who took it, or even close.

This was posted a while ago about how Theralizumab came close in clinical trials.

In its first human clinical trials, it caused catastrophic systemic organ failures in the subjects, despite being administered at a supposed sub-clinical dose of 0.1 mg per kg, some 500 times lower than the dose found safe in animals. Six volunteers were hospitalized on 13 March 2006, at least four of these suffering from multiple organ dysfunction.

The trial was a double-blind, randomized, placebo-controlled study, with two of the eight subjects receiving a placebo, and six receiving 1/500th of the highest dose used in previous experiments with cynomolgus macaques. All six of the trial subjects who received the drug were male, aged 19 to 34 (median 29.5); none had a notable medical history, and all were well in the 2 weeks before the trial. The drug was given by intravenous infusion, starting at 8am, with an interval of around 10 minutes between patients, and each infusion lasting from 3 to 6 minutes. Roughly fifty minutes after the first participant received his dose, he complained of a headache, and soon afterwards fever and pain. He took his shirt off, complaining that he felt like he was burning. Shortly after, the remaining participants who received the actual drug also became ill, vomiting and complaining of severe pain.

Shit got real very fast.