Rasputin reportedly drank enough cyanide-laced wine to have consumed four times the lethal dose, in addition to the cyanide in the pastries.
Moreover, Rasputin was a known drinker and both his autopsy and a report by his door lady confirm that he had been drinking heavily the night of his murder. "Alcohol, due to its acidity, speeds up the affect of potassium cyanide poisoning."
While it is possible for glucose or carbohydrate consumption to prevent cyanide poisoning, it is unlikely that Rasputin would have consumed sufficient amounts of either to counteract the amount of cyanide that Purishkevich and Yusopov suggest the consumed.
There are also inconsistencies between the stories that Purishkevich and Yusopov tell about Yusopov encountering a still-alive Rasputin in the basement. However, those inconsistencies are not conclusive, as one might expect confusion from someone who has just discovered that the man they murdered is actually alive. What are less easy to explain away are the problems with Purishkevich's discussion of pursuing Rasputin through the courtyard. Yusopov claims to have run out of the main entrance to help Purishkevich pursue Rasputin, thought he configuration of the house makes this claim unlikely, and Purishkevich makes no mention of Yusopov in the courtyard. According to Purishkevich:
he fired two shots from about twenty paces, within twenty paces Rasputin would have been at the gate. Both shots missed, he then says he bit his hand and aimed again, hitting Rasputin first in the back and then in the head. Remember all this time Rasputin is running away. He states that he went up to the body and kicked Rasputin's right temple. He says he was there for several minutes and does not recall Yusopov. In fact he says he found Yusopov sometime later retching in his bathroom.
According to Cullen, the blood stains in the photographs taken of the courtyard do not match either Yusopov or Purishkevich's accounts of Rasputin being shot. Nor do the bloodstains make sense when seen in light of Yusopov's cover-up, which involved killing a dog in the courtyard. He also alleges that there were other material inconsistencies in the evidence and the accounts of the murder that make it clear that the traditionally accepted account of Rasputin's murder is simply not accurate.
Whether or not Rasputin was killed in the manner that has been accepted for almost a century or whether another party was involved in his death is something that may never be known. What is known is that the forensic evidence does not appear to substantiate the accounts that the coconspirators have given of the murder. It is left to the individual to consider whether the lack of poison in Rasputin's stomach and his seeming inability to be murdered were because he was a powerful mystic, or because the story the coconspirators told did not reflect the actual events of this death.
Cash, Carolyn. 2009. Why Felix Youssoupov killed Rasputin: Motives for Murder of Russian
Holy Man. Vancouver: Suite 101. Online. Available from Internet, http://russian