Aldosterone response to metoclopramide is mediated through the autonomic nervous system in man

Metoclopramide-induced cardiac arrest

The authors report a case of cardiac arrest in a patient receiving intravenous (IV) metoclopramide and review the pertinent literature. A 62-year-old morbidly obese female admitted for a gastric sleeve procedure, developed cardiac arrest within one minute of receiving metoclopramide 10 mg via slow intravenous (IV) injection. Bradycardia at 4 beats/min immediately appeared, progressing rapidly to asystole. Chest compressions restored vital function. Electrocardiogram (ECG) revealed ST depression indicative of myocardial injury. Following intubation, the patient was transferred to the intensive care unit. Various cardiac dysrrhythmias including supraventricular tachycardia (SVT) associated with hypertension and atrial fibrillation occurred. Following IV esmolol and metoprolol, the patient reverted to normal sinus rhythm. Repeat ECGs revealed ST depression resolution without pre-admission changes. Metoclopramide is a non-specific dopamine receptor antagonist. Seven cases of cardiac arrest and one of sinus arrest with metoclopramide were found in the literature. The metoclopramide prescribing information does not list precautions or adverse drug reactions (ADRs) related to cardiac arrest. The reaction is not dose related but may relate to the IV administration route. Coronary artery disease was the sole risk factor identified. According to Naranjo, the association was possible. Other reports of cardiac arrest, severe bradycardia, and SVT were reviewed. In one case, five separate IV doses of 10 mg metoclopramide were immediately followed by asystole repeatedly. The mechanism(s) underlying metoclopramide's cardiac arrest-inducing effects is unknown. Structural similarities to procainamide may play a role. In view of eight previous cases of cardiac arrest from metoclopramide having been reported, further elucidation of this ADR and patient monitoring is needed. Our report should alert clinicians to monitor patients and remain diligent in surveillance and reporting of bradydysrrhythmias and cardiac arrest in patients receiving metoclopramide.

Respiratory failure following oral administration of metoclopramide

OBJECTIVE

To report a case of respiratory failure, possibly due to anaphylaxis or asthma exacerbation, following the administration of metoclopramide.

CASE SUMMARY

A 32-year-old white woman with a history of severe asthma and short-bowel syndrome was admitted for Hickman catheter line sepsis. Two doses of oral metoclopramide 10 mg in solution were administered for nausea and vomiting. Transient dyspnea followed the first dose of metoclopramide, but respiratory failure requiring intubation followed the second dose.

DISCUSSION

Respiratory failure has been reported with metoclopramide-induced movement disorders. Three other cases of respiratory failure from anaphylaxis or asthma exacerbation following metoclopramide administration have been reported. Respiratory failure in our patient may be due to anaphylaxis or bronchoconstriction from metoclopramide-induced cholinergic activity of the vagus nerve, possibly through inhibition of acetylcholinesterase.

CONCLUSIONS

The use of metoclopramide in patients with pulmonary dysfunction may warrant caution.

Effect of metoclopramide, ondansetron and granisetron on aldosterone secretion in man

The plasma aldosterone response following the administration of drugs with antagonist and agonist activity at Serotonin 3 and 4 (5-HT3&4) receptors has been examined in 9 healthy male volunteers receiving the following four treatments i.v. in a randomised, cross-over sequence: ondansetron 8 mg, granisetron 3 mg, metoclopramide 20 mg, and saline 20 ml. Metoclopramide significantly increased the mean plasma aldosterone level to 196% of basal level at 5 min. It rose to 234% at 15 min and remained at more than 185% of basal level for the duration of the experiment. The response to ondansetron and granisetron did not differ significantly from placebo. If dopamine antagonism is discounted, the results suggest that metoclopramide-induced aldosterone secretion results from its agonist activity at 5-HT4 receptors, although slow neuronal depolarization via an unidentified receptor remains a possibility. Antagonism at the 5-HT3 receptor plays no role, as the selective antagonist, granisetron, did not elicit a significant response. It seems unlikely that the 5-HT4 receptor is the second, low affinity binding site of ondansetron, unless it had no agonist activity at this receptor.

Effects of enhancement and antagonism of 5-hydroxytryptamine activity on metoclopramide-induced aldosterone secretion in man

This study examines the contribution of the serotonergic system to metoclopramide-induced aldosterone secretion. Six normal male volunteers, at 13 h, 9 h, and 2 h before the i.v. bolus of 10 mg metoclopramide, received the following pre-treatments in a single-blind cross-over randomized sequence: fluoxetine 20 mg, metergoline 6 mg, pizotifen 0.5 mg, or methysergide 2 mg. One regimen consisted of metoclopramide alone. Pizotifen and fluoxetine pre-treatment increased metoclopramide-induced aldosterone secretion significantly after 15 min, for the duration in the case of fluoxetine, and up to 90 min with pizotifen. The increase with metergoline was never significant, while methysergide had a negligible influence. Serotonin is postulated to play an intermediary role in acetylcholine-facilitated aldosterone release. The mechanism of fluoxetine-mediated serotonin increase is a re-uptake inhibition and that of pizotifen is suggested to be the elimination of an auto-inhibitory mechanism.

Atrial natriuretic factor inhibits metoclopramide stimulated aldosterone release in man

1. Atrial natriuretic factor (ANF) has an inhibitory effect on angiotensin II and ACTH stimulated aldosterone secretion in man. The selectivity of this aldosterone suppressing effect of ANF is unclear in man. The present study investigated the effect of ANF on the increase in plasma aldosterone due to metoclopramide in man. 2. Eight normal male volunteers were studied on three occasions. Metoclopramide (10 mg slow i.v.) was given on all study days and each volunteer was randomised to receive 45 min infusion of either 5% D-glucose (placebo) or ANF (99-126) 3 or 15 pmol kg-1 min-1. 3. Metoclopramide increased plasma aldosterone to approximately 170% of baseline levels (P less than 0.01). Concomitant infusion of ANF 3 pmol kg-1 min-1 and 15 pmol kg-1 min-1 significantly attenuated this rise in plasma aldosterone to approximately 130% (P less than 0.05) and 110% (P less than 0.01) of baseline values respectively. 4. It is suggested, in the light of previous findings, that the inhibitory effect of ANF represents a non-selective action of ANF on aldosterone release.

The effect of neostigmine on metoclopramide-induced aldosterone secretion after the administration of muscarinic antagonists in man

In this study the effects of neostigmine on metoclopramide-induced aldosterone secretion were examined in the presence of a relatively selective M1-antagonist, pirenzepine and of a non-selective muscarinic antagonist, atropine. Six normal male volunteers received metoclopramide, 10 mg i.v. on three different occasions, each study day being preceded by a day in which the intake of sodium and potassium was limited. The dosing was either metoclopramide alone or combined with either neostigmine and pirenzepine or with neostigmine and atropine. Serum aldosterone increased significantly with all three regimens. The highest levels were attained with the metoclopramide/neostigmine/pirenzepine regimen and those were significantly higher than those after metoclopramide alone and also, from 45 min onwards, from those after the metoclopramide/neostigmine/atropine regimen. The results of this investigation suggest that the metoclopramide-induced aldosterone secretion in humans is augmented by an accumulation of acetylcholine at the nerve-zona glomerulosa junctions and that the receptors mediating aldosterone secretion are of the M2-subclass of muscarinic receptors.

Effect of neostigmine on metoclopramide-induced aldosterone secretion in man

This study examines the role of a neostigmine-induced increase in acetylcholine on the aldosterone stimulating effect of metoclopramide. Six normal male volunteers received the following three treatments in a cross-over randomized sequence: neostigmine, 0.5 mg s.c.; metoclopramide 10 mg i.v.; and neostigmine 0.5 mg s.c., followed by metoclopramide 10 mg i.v. Metoclopramide increased serum aldosterone significantly to 161% of basal level at 15 min. With neostigmine aldosterone levels peaked (129%) significantly at 30 min. In the presence of neostigmine, however, the metoclopramide-induced aldosterone response was blunted significantly. These results would suggest that presynaptic autoreceptors depresses the continued output of acetylcholine, thereby blunting the aldosterone responses to metoclopramide significantly.