Bujutsu: The Path asked me to touch on how to respond to substance altered attackers. People that are high on drugs present a variety of challenges.
1. They are less likely to respond to reason
2. They are more likely to act erratically
3. They are less likely to experience or react to pain
4. They are more likely to have increased strength
I've written on the topic of pain compliance in the past. They have a time and a place, but during a knife attack is not one of them. You cannot and will not have enough time to determine if a person is high on drugs in formulating your response.
The key point to take away is that any survival technique you use must work on everyone, regardless of what substances they've ingested.
I also once had to subdue a guy on crystal meth. I wasn't alone, but no one could do anything with him. Distraction strikes did nothing, and he was stronger in his drug fueled state than the 3 guys trying to get him into handcuffs. Ultimately, I was able to apply a shoulder lock, putting him face down into a couch. This immobilized him, but he didn't feel any pain. I found a way to immobilize him. He had no leverage or room to resist, so he was stuck. We could have hit him all day and I doubt it would have done anything. I had taken him, or a part of him, out of the equation.
This same concept applies to knife survival techniques. You have to take the individual, or the delivery system of the attack (hand, arm, shoulder etc) out of the equation.
If you are attacked with a knife, unless you can generate immediate distance and cover, you must prioritize getting control of the knife and the knife wielding limb. With the potentially fatal nature of knife attacks, and the relatively high chance of your attacker being on some form of drug, you need to destroy whatever you get a hold of. You need to break the arm, wrist, hand or shoulder of your attacker. And you need to mangle it. It sounds gruesome, but you must separate whatever part you break from whatever part it's attached to. You must make it unusable to your attacker. This is crucial as they may not respond to the pain of the injury. If the drugs make them immune to pain, then the part that they are using to attack must be taken out of commission. Taking the example of our broken legged friend, he could still run, but that's because his leg was still essentially held together. Had it been broken more fully and completely severed, he would not physically be able to continue.
In the case of a knife wielding attacker, if he (or she) doesn't feel their arm break, for instance, then when they go to use it again for another attack, it must not work for this purpose. Not to put too fine a point on it, but if their forearm is hanging down and the hand is backwards, they won't be able to hold or use the knife.
You cannot rely on anything other than the simplest, most destructive techniques to survive a knife attack. You have no way to know what your attacker is capable of or what substances they have taken. There are no less serious knife attacks. Each and every one can be fatal. Knowing this, every technique you study or learn must be effective, simple and inflict the maximum damage to you attacker. They're nasty, but it's a matter of life or death.