Drug MLDs

The tables listing the drugs used in drug poisoning deaths show that it is possible to use drugs as a successful method of suicide using a variety of different drugs. One important success factor is the dosage – how much of any particular drug needs to be taken for it to be lethal.

Minimum lethal doses (MLDs) were historically calculated based on animal testing, with the results extrapolated for humans. After all, you can’t test how much of a certain drug is required to make a human die. In a study by 18 pharmaceutical companies in 2008¹, it was found that the single dose acute toxicity test that was normally used to identify the minimum lethal dose of a medicine had little or no value in assessing the risk to humans.

Part of the problem is that humans come in such a variety of different shapes and sizes. Certain drugs might need much higher dose in someone weighing 100kg then 60kg, although if it is a drug that affects the brain the dose might be very similar. Furthermore, according to a study by T Ludden quoted in Stone², the effect of some drugs on men and women can be marked, with variation between the sexes 100% or more.

Also, exposure to certain drugs generates a tolerance to them, so that much higher doses are required to have an effect. For example, people taking morphine for long term pain control often need increased doses over time to have the same effect.

For all these reasons, predicting MLDs in humans is very difficult. So beware.

With that proviso, there have been tables published on MLDs. Two such tables are presented below (note some entries have footnotes associated). The first figure in each entry is quantity, the second dosage strength. The first column has MLDs from a blog post http://moriahconqueringwind.vox.com (site now closed) with no information as to the source of the information. The figures in the second column were taken from a posting on alt.suicide.methods, reportedly from a book “The Prediction of Suicide”. In his book, Stone² points out that lethal doses quoted in medical reviews are generally a range of values, and that the MLD can vary significantly between sources.

So whilst there is a table of MLDs below, it must be highly questionable how much accuracy can be attributed to this information. We have received a number of emails from readers of this site questioning the validity of certain MLDs, but there simply is no easy-to-access guide for MLDs of most the drugs in this table. The section Which drug provides more information on lethal drugs that are commonly used for suicide, and the notes to the table below proving important information on doses for some of the more commonly discussed lethal drugs.

In the table below, the first figure is the number of pills, and the second figure is the dosage of each pill.

1. Generic name in brackets
2. 1000 milligrams (mg.) = 15 grains (gr.) = 1 gram (gm.)
3. Nitschke and Stewart³ state that Propoxyphene commonly comes in 100mg tablets, and state an MLD of 10 grams (100 tablets of 100 mg), taken together with long acting sleeping tablets like Oxazepam.
4. Nitschke and Stewart³ state that the MLD of Amitriptyline is 5gm, and the most commonly supplied dosage is 50mg, meaning 100 x 50mg would be required, taken together with long acting sleeping tablets like Oxazepam. The Alt Suicide Holiday (ASH) website⁴ states MLD is 7-8 gm. Both sources recommend taking the drug in combination with others.
5. Nitschke and Stewart³ state that the oral form of Nembutal sold in 100ml bottles (sterile bottles) at a concentration of 60mg per ml (i.e. 6 grams in a bottle) is enough to provide a peaceful death, although in some cases this can take up to 24 hours. For powdered Chinese Nembutal which is sold in higher quantities, 10grams dissolved in 50ml of water is suggested, and forum posts suggest this is a more reliable dose whilst also being easier to ingest. They recommend ceasing any other medications a few days before taking Nembutal. There is also non-sterile (green coloured) Nembutal that is concentrated 300mg per ml, in which case a 50ml sample equates to 15 grams, and is more than enough for a peaceful death. Compassion in Dying⁵ recommend 6g – 9g of Nembutal. Dignitas use 15 grams of a concentrated soluble form of Nembutal that can be swallowed in a few mouthfuls.^{3, 6}

The blog posts had the following notes:

1. Minimal lethal doses were estimated from the literature and computed by assuming the victim would be a healthy male, 35 years of age weighing 150 pounds. This yields a conservative estimate since the amounts listed would be more toxic in all other people, except for heavier males.
2. When any ingestion is accompanied by ETOH (ethyl alcohol), it increases the toxicity level by approx 50%.
3. If it is established that a person is a regular drug user, then raise the number of milligrams for MLD by 33%.
4. To avoid mishap one probably ought to take 150% the minimum lethal dose. Ending up a vegetable with liver failure isn’t exactly a kinder fate than death.

The point about alcohol is in particular worth noting, and referring back to data presented in the section Suicide statistics, it is worth noting that this is present in around a quarter of deaths due to drug poisoning.

Morphine

There is no mention in the MLD tables of morphine, one of the reasons probably being that people become tolerant to morphine (and similar drugs like codeine) over time. In a 1977 study, Kaye & Tudó de Lewis⁷ studied the toxicology of morphine and some other drugs. They estimated the following MLDs:

They mention that tolerance to these drugs is lost after a period of abstinence, and many overdoses are as a result of people taking their previous dose of the drug after a period of abstinence.

In The Peaceful Pill Handbook, Nitschke and Stewart³ conclude that morphine is an unreliable method of suicide simply due to the difficulty in predicting what the lethal dose is.

Heroin

Whilst one does read about death by heroin overdose, as a method of suicide it is fraught with difficulty. Firstly, it is impossible to know the purity of any drug bought off the street. Second, even if the purity was known, heroin suffers from the same drawbacks as morphine in terms of calculating the minimum lethal dose, in that tolerance rises over time. For these reasons it is not a reliable method.

Other barbiturates

Nitschke and Stewart³ claim that10g of Phenobarb (250 of the 30mg tablets) and Pentothal (thiopentone sodium) (10gm/20 ampules dissolved in 50ml of water) are also both lethal, and potentially easier to obtain than Nembutal. They also mention that Dilantin (phenytoin sodium) can be used to increase the potency of Nembutal. More information on all of these are in The Peaceful Pill Handbook.

Sources

1. S Robinson et al, A European pharmaceutical company initiative challenging the regulatory requirement for acute toxicity studies in pharmaceutical drug development. Regul Toxicol Pharmacol. 2008 Apr. (Discovered from http://www.labtechnologist.com/Industry-Drivers/Thousands-of-rodents-saved-from-drug-testing.)
2. Geo Stone, Suicide and Attempted Suicide, 1999.
3. Dr Phillip Nitschke with Dr Fiona Stewart, The Peaceful Pill eHandbook, revised Dec 2010.
4. Alt Suicide Holiday website, http://ash2.wikkii.com/wiki/Amitriptyline_Cocktail.
5. TA Preston & R Mero, Observations concerning terminally ill patients who choose suicide, published within MP Battin & AG Lipman, Drug use in assisted suicide and euthanasia 1996. (Excerpts can be viewed free at http://books.google.co.uk/books?isbn=1560248149).
6. Ludwig Minelli, Wenn Sie das trinken, gibt es kein Zurück (When you drink, there is no turning back), article in Der Tagesspiegel 29 March 2008 (www.tagesspiegel.de/weltspiegel/Sterbehilfe-Dignitas-Minelli;art1117,2502357).
7. S Kaye & A Tudó de Lewis, Heroin overdose on the rise again? (Toxicology of morphine), Bol Asoc Med P R 1977 (from http://www.md.rcm.upr.edu).