The Reproducibility of the Mecholyl Test

Abstract

The reproducibility of certain parameters of the Mecholyl test was investigated in 23 psychiatric in-patients of mixed diagnoses. Each subject was tested on three occasions within one week, only those whose clinical state remained unchanged during that time being used. Two changes were made in an effort to improve reproducibility: 1. methacholine dosage was adjusted to body weight (5 µg./kg./ minute), and 2. the drug was given intravenously over a period of six minutes, in order to overcome the variation in absorption rates likely with intramuscular injection. All the drug response parameters chosen showed a high degree of reproducibility. The quotient—Area of decrease in Blood pressure Area of increase in heart rate, was the most reliable, with an intra-class correlation coefficient of .96.