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

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.

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.

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).

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.

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.