Redux: do little bellyachers grow up to become big bellyachers?

Centrally Targeted Pharmacotherapy for Chronic Abdominal Pain: Understanding and Management

Chronic abdominal pain has a widespread impact on the individual and the society. Identifying and explaining mechanisms of importance for the pain experience within a biopsychosocial context are central in order to select treatment that has a chance for symptom reduction. With current knowledge of brain-gut interactions, chronic abdominal pain, which mostly appears in functional gastrointestinal disorders, to a large extent involves pain mechanisms residing within the brain. As such, the use of centrally targeted pharmacotherapy as an effective treatment option is obvious in a selected number of patients. The antidepressants are most common, but also other classes of medications can be used, either alone or in combination. The latter option refers to when there is insufficient effect of one drug alone or side effects limiting dosage, and when combined in lower doses, certain drugs give rise to augmentation effects. This chapter outlines basic mechanisms of importance for the understanding of chronic abdominal pain and the pharmacologic treatment options.

Mechanism-Oriented Therapy of Irritable Bowel Syndrome

Irritable bowel syndrome (IBS) is a common and well-accepted diagnosis but often imprecisely applied to patients in usual clinical practice. Diagnosis is entirely based on symptom criteria that tend to include broad strata of abdominal complainers. Established criteria for diagnosis are strictly followed in controlled clinical trials for new therapeutic agents, but physicians are more lax in the clinic. Predictably, in light of the above ambiguities, many pathogenetic mechanisms and pathophysiological disturbances appear to be involved in IBS, but so far no mechanism-based subgroupings to guide specific therapy have been soundly established. Thus, diverse therapeutic approaches coexist and are discretionally prescribed by attending clinicians on the basis of major manifestations (i.e., diarrhea-predominance or constipation-predominance), more or less apparent psychological disturbances, and patient preferences (pharmacological versus dietary or microbiological approaches). In this review, we have attempted to update scientific knowledge about the more relevant disease mechanisms involved and relate this more fundamental basis to the various treatment options available today.

Centrally targeted pharmacotherapy for chronic abdominal pain

BACKGROUND

Chronic abdominal pain in the context of the functional gastrointestinal disorders departs from a more traditional approach to treating gastrointestinal symptoms. Chronic abdominal pain involves a dysregulation of brain-gut modulation of afferent signaling, so treatments directed toward the gut are not usually sufficient to achieve a clinical response. Rather the methods of treatment depend on re-establishing central pain regulation.

PURPOSE

A conceptual model of predisposing, precipitating, and perpetuating factors is used to explain how a situation of chronic pain develops and it provides the evidence for central neuron degeneration as relevant to this chain of events. The rationale for centrally targeted medications, in particular antidepressants, is discussed with regard to effects independent of their role in treating psychiatric disorders: with regard to downregulation of afferent pain signals and their potential role in neuron proliferation. Finally, guiding examples of which drug to use and treatment combinations involving multiple drugs, augmentation treatment, are outlined and some brief clinical cases of centrally targeted pharmacotherapy.