We apologize in advance. But it was inevitable that TCR would eventually have to tackle what may be the most boring topic in all of psychiatry, if not medicine in general: Drug-drug interactions.

Drug interactions are enormously complicated. In tried and true TCR fashion, I have tried to make this topic easier to stomach. Nonetheless, you can skip this article if you make a decision to avoid prescribing the following medications ...

When it comes to Lithium, you can (thankfully) forget all about the P450 enzymes, because they don't touch this salt. Lithium enters the bloodstream, accomplishes its mysterious mood-stabilizing duties, and then is simply whisked out of the body intact by the kidneys via urine. So with Lithium, it's all about kidneys.

Dr. Sandson, you've just published the definitive casebook on drug interactions (1), and you obviously have thought long and hard about the issue. What do you think psychiatrists really need to know about drug-drug interactions?

The concept of drug-drug interactions in psychiatry surfaced surprisingly recently. In 1988, a small letter was published in the American Journal of Psychiatry by Dr. D. A. Vaughan, a psychiatrist in practice in Wichita, Kansas. Dr. Vaughan described two women he had been treating for depression with tricyclics.

Alan Ringold, M.D., is a psychiatrist in private practice in Palo Alto, California. He is particularly astute when it comes to drug interactions, and he clearly made the right call in the following situation.