Drug Tolerance, Drug Overdose and Lethal Dose

The Seattle Police would usually quote drug tolerance to explain the alleged high amount of morphine found in Cobain's body. So what is drug tolerance?

What is drug tolerance?

Drug tolerance is a pharmacological concept where repeated and frequent use of a specific drug creates a tolerance which prevents the drug to activate. When a person has a high drug tolerance regular doses of the drug will not work on them. They will need to increase the amount of the dose to receive the desired effects of the drug. Alternatively, abstaining and substituting the drug can decrease the drug tolerance and this is one way to consume the drug without having to increase the dose amount.

Some people mistake drug tolerance to mean a person's limit to how much drug they can take without getting overdosed. That is not what drug tolerance means. Passing through drug tolerance does not lead to an overdose. Rather it only leads to the drug to activate and perform its effects.

What is drug overdose?

Drug overdose or simply overdose (OD) is when a person takes an amount of drug which is more than what they need. You only need to take the amount enough to activate the drug's desired effects. An overdose causes the normal symptoms of the drug to magnify which can be potentially fatal. For instance, heroin would bind to the brain's opioid receptors controlling the functions of breathing and heart rate. A person who is overdosed with heroin will have symptoms involving abnormal breathing and slow or fast heart rate. A person not overdosed with heroin will have mild symptoms involving breathing and heart rate.

To prevent a person from accidentally taking an overdose experts would do calculations and studies and set a lethal dose.

For example, it is claimed that the author of the book Heroin Addiction. J.J. Platt suggested that 75mg dose of heroin is a lethal dose. He also claimed that 75mg of heroin would result in 0.5mg/L of morphine in blood for a 150 pound man.

What is a lethal dose?

A lethal dose is the amount of drug that can kill a person if administered. A lethal dose always causes an overdose. Estimating a lethal dose is not always accurate. For example, a person can take more than 75mg of heroin without suffering an overdose. How? Drug tolerance.

[NOTE: Drug tolerance does not prevent drug overdose but for an overdose to happen the drug must be activated. A lethal dose causes an overdose. There is no fixed lethal dose. Lethal dose varies from person to person.]

Now to the Cobain Case.

Cobain was found with 1.52mg/L of morphine in his blood. Several people who support the murder theory quote that the amount of morphine found in Cobain's blood is three times the amount found from taking a lethal dose of heroin. This quote comes from a book called Heroin Addiction by J.J. Platt published in 1986 which claimed that 0.5mg/L of morphine would be found in blood if a person takes the lethal dose (75mg) of heroin. The theorists argue that Cobain was given three times the lethal dose (225mg) of heroin and that he was overdosed, possibly dead and thus was incapable of writing a suicide note and use a shotgun to kill himself.

The Seattle Police would quote drug tolerance as the reason why Cobain had a high amount of morphine in his blood. One explanation is that since Cobain was reported to be a severe addict it is expected that he had built a high tolerance and would require a large dose of heroin for the drug to work on him. This would result in a high amount of morphine in his blood than usually found. Another explanation, particularly from Dr. Donald Reay who was the Chief Medical Examiner of this case, is that drug tolerance prevented the drug (heroin) to work on Cobain and he was at a normal state when he committed suicide.

I have a different opinion. In my blog post, The Toxicology Report, I wrote that 1.52mg/L of morphine in blood does not prove or indicate that Cobain was given three times the lethal dose. Rather the amount signifies that Cobain took heroin some time before his death. I also explained how the body works to eliminate the drug and that heroin goes through metabolism where it changes into morphine. Morphine does not stay in the blood forever, it would be transferred to the urinary bladder and as it does, less and less morphine remains in the blood. It is said that it takes 5 hours to 2 days for morphine to become undetectable in blood samples and it takes 2 to 7 days to become undetectable in urine samples. Since most of the drug would be transferred from the blood to the urinary bladder, blood samples are not reliable to perfectly estimate how much heroin was taken. Urine samples may give a better idea but it is also not perfect. 

The main point that I want to say is that the amount of morphine found in Cobain's blood does not prove he was given a lethal dose. It only proves that he had taken heroin before he died. And it also indicates that Cobain did not shoot himself immediately after taking heroin. Rather he shot himself after a considerable time had passed.

I hope I made you understand what terms like drug tolerance and lethal dose means. I hope the information helps you to understand and make better decisions regarding the Cobain Case. I also suggest to check out the links provided in this post. Texts in blue colour have links to other sites and online articles or videos that contain information which I recommend you to check.

-Indya





Recommended videos and online articles:

Unsolved Mysterious Episode of the Cobain Case. 

The Lethal Dose Misunderstanding.

Drug Facts on Heroin.

How Long Heroin Stays In The System.

Heroin Drug Profile.

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