Prolonged central apnoea after intravenous morphine administration in a 12-year-old male with a UGT1A1 loss-of-function polymorphism.

When appropriate, physicians should enquire about prior receipt of opioids, in both the patient and family, to be better prepared for potential adverse reactions. In the patient with excessive sedation or respiratory depression to standard doses of morphine, genetic testing may be warranted, especially if there is a family or past history that supports a metabolic defect in morphine metabolism and/or excretion.