Opioid Analgesic Drugs

Abstract

Opioid analgesics are one of the most commonly administered groups of drugs in hospitals. These drugs show common structural features, bind specifically to opioid receptors and possess morphine-like pharmacologic action. Tramadol differs from other opioid analgesics in its monoaminergic activity as well as its affinity for the μ opioid receptor. Many opioids are potent histamine releasers producing hemodynamic changes and anaphylactoid reactions, but there seems to be no direct relationship between the histamine plasma concentrations and these changes. True IgE antibody-mediated immediate allergic reactions to opioids are uncommon, although some anaphylactoid reactions are interpreted as allergic, emphasizing the need to investigate whether or not reactions have an immune basis. The histamine-releasing properties of opioid drugs sometimes hamper skin testing, and general unavailability of specific IgE antibody tests contributes to the failure to investigate reactions. Reactions to tramadol, whether anaphylactoid or IgE antibody-mediated, are rare, and the drug is generally considered to be safe with a low potential for adverse reactions. Clinical implications for the diagnosis of opioid drug-induced anaphylactoid and anaphylactic reactions are discussed.