Introduction: The comorbidity between obsessive-compulsive disorder (OCD) and bipolar disorders (BDs) is a frequent and severe condition characterized by a chronic course, high suicidal risk and tendency towards chronicity and treatment non-response. It represents a real challenge to psychiatrists, while requiring a careful and appropriate therapeutic management consisting in the combination of serotonergic antidepressants (ADs), such as serotonin reuptake inhibitors (SRIs), with mood stabilizers. This combination, like any other, raises the problems related to drug interactions that may lead to pharmacokinetic and pharmacodynamic changes, resulting in the modification of the pharmacologic effect and safety profile of a given compound. Areas covered: The aim of the present paper was to review the literature on the pharmacokinetic and pharmacodynamic changes resulting from the interactions of the different drugs prescribed in the OCD-BD comorbidity. Expert opinion: The literature data on pharmacokinetic and pharmacodynamic changes due to interactions of drugs commonly prescribed in the treatment of the OCD-BD comorbidity are extremely limited, and the information is inferred by findings gathered in psychiatric patients suffering from other disorders. This represents a gap in psychopharmacology that should be filled by specific studies on this important topic.
Keywords: Obsessive-compulsive disorder; bipolar disorders; comorbidity; drug interactions; pharmacodynamics; pharmacokinetics; pharmacological treatments.