RESUMO
OBJECTIVE: To assess the frequency of potential drug-drug interactions affecting cytochrome P450 (CYP)-mediated metabolism of opioids among adult and adolescent patients who underwent adenotonsillectomy. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary care university hospital. PATIENTS AND METHODS: A retrospective review was conducted of 279 patients who underwent adenotonsillectomy at the University of Rochester. The discharge medication list was reviewed for all patients, and their postoperative medications were compared with a reference list published by the Food and Drug Administration and the University of Indiana's Department of Clinical Pharmacology (Flockhart Table) to determine whether CYP-inducing or CYP-inhibiting medication was present. RESULTS: Out of 279 patients, 197 different medications were taken postoperatively. Approximately 70% of patients were taking 2 medications in addition to the standard postoperative analgesics (acetaminophen, hydrocodone, oxycodone, morphine, and/or ibuprofen). The 5 most commonly prescribed medications excluding the posttonsillectomy medications were oral contraceptives, ondansetron, amoxicillin, albuterol, and methylprednisolone. Four percent of patients were taking a medication that inhibits CYP3A4; <1% were taking a medication that induces CYP3A4; and 15% were taking a medication that inhibits CYP2D6. CONCLUSIONS: Nearly 20% of the patients in this cohort were taking a medication that may alter opioid metabolism through induction or inhibition of CYP3A4 or CYP2D6. Some of these interactions have the potential to be more clinically relevant than others, particularly interactions that can lead to enhanced toxicity of opioids due to accumulation of active metabolites.
RESUMO
OBJECTIVE: To evaluate the frequency of potential cytochrome P450 (CYP) drug-drug interactions affecting opioid metabolism among children undergoing adenotonsillectomy. STUDY DESIGN: Case series with chart review. SETTING: Tertiary care children's hospital. SUBJECTS AND METHODS: A retrospective review was conducted of 1000 patients undergoing adenotonsillectomy at Children's Hospital of Wisconsin. The discharge medication reconciliation form was reviewed. Each patient's list of medications was compared with various published sources to determine whether medications causing CYP inhibition or induction were present. RESULTS: There were 157 unique medications with systemic absorption given postoperatively to this patient cohort. Eight percent of patients were on at least 5 medications after surgery other than their posttonsillectomy medication. The 5 most commonly prescribed medications were albuterol, cetirizine, fluticasone nasal spray, montelukast, and polyethylene glycol. Per a list of known CYP inducers and inhibitors published by the US Food and Drug Administration, 30 (3%) patients were on a medication that inhibited CYP3A4; 1 patient was on a CYP3A4 inducer, prednisone; and 46 (5%) patients were on a medication that inhibited CYP2D6. CONCLUSIONS: A small fraction of patients undergoing adenotonsillectomy are on medications that potentially alter the metabolism of opioid pain medications. Given the narrow therapeutic index of opioids and increased sensitivity to opioids among patients with obstructive sleep apnea, drug-drug interactions need to be considered as they relate to whether an opioid is appropriate and at what dose.