Amlodipine toxicity in children less than 6 years of age: a dose-response analysis using national poison data system data.

BACKGROUND: Amlodipine is a long-acting calcium channel blocker capable of producing hypotension and dysrhythmia in overdose. The toxic doses of amlodipine in children are unclear.
OBJECTIVES: The purposes of this study were to describe amlodipine poisoning in children and to determine whether a dose-response relationship could be detected in this population using standardized call data from United States (US) poison centers. PATIENTS AND METHODS: 1251 amlodipine-only ingestions in children < 6 years of age were reviewed. Cases with doses coded as "Exact" or "Estimated" and with dose, age, and medical outcome were analyzed (n = 678). Ingestions reported as a "taste or lick" (n = 53) were included as a dose of 1/10 of the dosage form involved. A clinically important response was defined as bradycardia, hypotension, dysrhythmia, conduction disturbance, or hyperglycemia. The risk of such responses was examined over four dosage intervals (< 2.5 mg, 2.5-5 mg, 5.1-10 mg, and > 10 mg).
RESULTS: The median estimated dose ingested was 5 mg (range 0.25-200 mg). Clinically important responses developed in 27 patients (3.98%), and the prevalence of such response significantly increased from 0% for the lowest to 11.1% for the highest dose interval (p = 0.001). The smallest dose to produce a clinically important response was 2.5 mg (0.15 mg/kg). Children who ingested > 10 mg were 4.4 times more likely to develop clinically important responses than those ingesting < or = 5 mg.
CONCLUSION: Hypotension may occur in children with amlodipine doses as low as 2.5 mg. The National Poison Data System might provide useful insights regarding dose-response. Copyright 2010 Elsevier Inc. All rights reserved.