Metoclopramide slightly reduced absorption of quinidinefrom a sustained-release formulation in one study, but modestlyincreased quinidine levels in another.
A study of this interaction was prompted by case of a patient who was taking sustained-release quinidine (Quinidex) and whose arrhythmia became uncontrolled when metoclopramide was added. In a crossover study,9 healthy subjects were given either metoclopramide 10mg every 6 hrs for 24 hrs before, and 48 hrs after, a single 600- or 900mg oral dose of quinidine sulfate or quinidine alone. It was found that metoclopramide caused a mean 10 % decrease in AUC of quinidine, although two subjects had decreases of 22.5 and 28.1%,respectively. The elimination rate constant was unaffected.(See reference number 1)Another study in patients taking a sustained-release formulation of quinidine bisulfate 500mg every 12 hrs found that metoclopramide 10mg three times daily increased mean plasma levels measured 3.5 hrs after last dose of quinidine by almost 20%, from
to 1.9 micrograms/mL,and at 12 hrs by about 16%, from 2.4 to
Not understood. Metoclopramide alters both gastric emptying time and gastrointestinal motility, which can affect quinidine absorption.
Direct information seems to be limited to these studies using different quinidine preparations. The outcome of concurrent use is uncertain,but generally seems small.
Yuen GJ,Hansten PD, Collins J. Effect of metoclopramide on the absorption of an oral sustained-release quinidine product. Clin Pharm (1987) 6, 722–5.
Guckenbiehl W,Gilfrich HJ, Just H. Einfluß von Laxantien und Metoclopramid auf die Chin-din-Plasmakonzentration während Langzeittherapie bei Patienten mit Herzrhythmusstörugen.Med Welt (1976) 27, 1273–6.