Prescription
opioid use has increased rapidly in developed countries, as have fatalities and other related adverse events. This review examines the intrinsic characteristics of
opioids, including their mechanisms of action and pharmacokinetic and pharmacodynamic properties, to determine how the use of a regonised pharmacological remedy for a medically confirmed ailment could result in an accidental fatality.
Opioids trigger biological processes that inhibit their own
therapeutic effect. Prolonged use of
opioids can result in activation of pronociceptive systems, leading to
opioid-induced
hyperalgesia and tolerance, while
opioid metabolites can antagonise the antinociceptive action of the parent drug, also leading to
opioid-induced
hyperalgesia and tolerance.
Pain stimulates respiration and counteracts the
respiratory depression effect of
opioids.
Analgesia from
opioids leads to loss of this protective mechanism, leading to increased risk of death due to
respiratory failure. Increased patient counseling during
opioid prescribing and dispensing, and limiting prescription to short-term use in non-malignant
pain, may decrease the adverse effects of
opioids. The vast majority of patients who unintentionally experience serious adverse events from pharmaceutical
opioids do not start out as drug seekers. Even
opioid use within prescribing guidelines can place some patients at risk of death and may prevent patients from seeking help for prescription
opioid dependence.