Some commonly prescribed psychotropics are highly lethal
The relative lethality of many commonly prescribed psychiatric medications, including those frequently used to reduce suicidality, varies tremendously. For example, it is widely known that the first-line mood stabilizer lithium has a narrow therapeutic window and can rapidly become toxic. If a patient becomes dehydrated, even a normal lithium dose can be toxic or lethal. Lithium has a relative lethality of 1,063% (Figure 2). Clozapine has a relative lethality of 1,112%. Valproic acid has an even higher relative lethality of 1,666%. By contrast, aripiprazole and olanzapine have a relative lethality of 10% and 35%, respectively. For preventing suicide, prescribing a second-generation antipsychotic with a lower relative lethality may be preferable over prescribing a medication with a higher relative lethality.
Figure 2
According to U.S. poison control centers,3 from 2000 to 2014, there were 15,036 serious outcomes, including 61 deaths, associated with lithium use, and 6,109 serious outcomes, including 37 deaths, associated with valproic acid. In contrast, there were only 1,446 serious outcomes and no deaths associated with aripiprazole use.3 These outcomes may be underreported, but they are consistent with the mathematical model predicting that medications with a higher relative lethality will have higher morbidity and mortality outcomes, regardless of a patient’s intent to overdose.
Many psychiatrists have a preferred antidepressant, mood stabilizer, or antipsychotic, and may prescribe this medication to many of their patients based on familiarity with the agent or other factors. However, simple math can give the decision process of selecting a specific medication for a given patient a more quantitative basis.
Even a small reduction in suicide would save many lives
Ultimately, the math problem comes down to 4 minutes, which is approximately how long the brain can survive without oxygen. By prescribing medications with a lower relative lethality, or by prescribing a less-than-30-day supply of the most lethal medications, it may be possible to decrease overdose morbidity and mortality, and also buy enough time for emergency personnel to save a life. If simple math can put even a 1% dent in the rate of death from suicide, approximately 8,000 lives might be saved every year.