|Pills for mood disorders.
Lithium, just plain lithium (as a salt), has been used for decades as a treatment for manic-depressive disorders and other illnesses that effect the affect. There aren't very many elements that are used as medical treatments (other than as nutritional supplements like iron and calcium). Two examples, with links to articles about their uses, are carbon (legitimate) and phosphorus (historical). Although the pills actually contain a lithium salt (lithium carbonate), it is the simple lithium that does the work. One theory is that because it is in the same column in the periodic table as sodium and potassium (all are alkali metals), it is able to stand in for them in their important role in the transmission of nerve impulses. By modifying in some poorly understood way how nerve signals propagate, lithium just happens to calm mood swings.
An element is certainly a rather blunt instrument compared to, say, a carefully crafted organic molecule, but if it does the job, who's to complain?
The source of this sample, Raph Levien, is as fascinated as I am by the fact that plain lithium is still a popular mood-stabilizing medication. A family member of his switched from lithium to a different medication around the same time he discovered my Periodic Table, so naturally he thought of contributing the leftover pills to the table. (There's a lesson here for anyone reading this who has a spare element handy....)
I was a bit surprised at how many pills he sent, especially after reading that as few as 20 can be fatal. (The toxic dose is very close to the therapeutic dose, and since these pills are given to people who are, well, depressed, you can imagine that some care has to be take to avoid suicide attempts!) I've sealed a sub-lethal dose in a plastic display container and locked the rest up for safekeeping.
Raph also supplied the following interesting URLs about lithium as a medication:
The purity (weight-percent lithium) of the sample was easy to calculate (especially after Yehoshua Sivan pointed out the error in my first attempt). The pills weigh 0.4163g each and are clearly labeled as containing 300mg (0.3g) of lithium carbonate (Li2CO3) each. Multiply this ratio by the ratio of twice the atomic weight of lithium to the molecular weight of lithium carbonate and you learn that the pills are about 13.6% elemental lithium.
Source: Raph Levien
Contributor: Raph Levien
Acquired: 30 December, 2002
Text Updated: 11 March, 2007
Sample Group: Medical