Clinical Pharmacology of Antidepressants. Clinical and Pharmacological Approaches to Drug Selection in Depressive Disorders.

Depression is one of the commonest reasons people seek help from doctors, and it is not a minor one. The World Health Organization lists it among the leading causes of disability worldwide, and an estimated 5% of adults live with it at any given time. A good part of the burden is hidden: patients often turn up with insomnia, pain, fatigue or palpitations, and the mood problem only emerges once the doctor asks about it. For a future physician this matters, because antidepressants are no longer prescribed only by psychiatrists. Family doctors and internists write most of the prescriptions, and they need to know what these drugs actually do in the body. The aim of this article is to review the clinical pharmacology of the main antidepressant groups (their mechanisms, pharmacokinetics, adverse effects and interactions) and then to show how this knowledge is turned into a practical choice of drug for a particular patient. The word choice is deliberate. Large meta-analyses show that the common antidepressants work better than placebo but differ only modestly from each other in average efficacy. What differs a great deal is the side-effect profile, the interaction risk and the fit with the patient's symptoms and other illnesses. That is where clinical pharmacology earns its place. The tables and figures were prepared to summarise the material; the numerical values for half-lives and efficacy are approximate and are taken from the sources listed at the end.