Pharmacotherapy principles in consultation-liaison psychiatry

Consultation-liaison psychiatry is the subspecialty of psychiatry concerned with medically and surgically ill patients. The consultant needs to have knowledge of psychotherapeutic and psychopharmacological interventions as well as knowledge of the wide array of medicolegal aspects of psychiatric and medical illness and hospitalization. Psychopharmacological interventions are an essential part of the management of the medically ill. Numerous physical conditions may cause, exacerbate or first present themselves as psychiatric syndromes, and appropriate use of psychopharmacology necessitates a careful consideration of the underlying medical illness, drug interactions, and contraindications. In addition, many medications used in the treatment of medical/surgical illness are associated with psychiatric syndromes. Therefore, the consultant must be knowledgeable about the psychiatric effects of medications as well as the specific indications for psychopharmacological interventions. Pharmacotherapy of the medically ill often involves modification in dosage (e.g., to account for older patients with an increased volume of distribution, a decreased rate of metabolism, and an increased physiologic reactivity). Furthermore, modifications may be necessary because of liver, kidney, or cardiac disease, or because of potential for multiple drug–drug interactions. Pregnancy presents another challenge, with concerns regarding potential teratogenicity.