Linearity of metoclopramide kinetics at doses of 5-20 mg

Is metoclopramide beneficial for the postpyloric placement of nasoenteric tubes? A systematic review and meta-analysis of randomized controlled trials

Background

Metoclopramide is frequently prescribed as an adjuvant for the postpyloric placement of nasoenteric tubes (NETs). However, a recent meta‐analysis showed that metoclopramide was not beneficial in adults. Thus, this study aimed to reevaluate the effect of metoclopramide on the postpyloric placement of NETs.

Methods

A systematic search of PubMed, Embase, the Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure (CNKI), and Wanfang data was conducted up to August 2020 for randomized controlled trials (RCTs) comparing metoclopramide with placebo or no intervention. Trial sequential analysis (TSA) was used for the primary outcomes (the success rate of the postpyloric placement of NETs).

Results

Seven eligible RCTs that included 520 participants were identified. The results of the pooled effect sizes showed that metoclopramide significantly facilitated the postpyloric placement of NETs (relative risk [RR], 1.48; 95% CI, 1.11–1.97; P = .007; I² = 37%). However, the risk‐of‐bias assessment and the TSA results indicated that the qualities of the RCTs and the sample sizes were insufficient to confirm the efficacy of metoclopramide. Further subgroup analysis revealed that successful postpyloric placement was more pronounced in studies in which spiral NETs were employed (RR, 1.85; 95% CI, 1.41–2.43; P < .001; I² = 0%). Additionally, overall adverse events were minimal.

Conclusions

The evidence accumulated so far was not strong enough to demonstrate metoclopramide's beneficial effects on the postpyloric placement of NETs. Further high‐quality, large‐sample RCTs are required to elucidate the effects of metoclopramide.

Gastroparesis, metoclopramide, and tardive dyskinesia: Risk revisited

BACKGROUND

Metoclopramide is primarily a dopamine receptor antagonist, with 5HT₃ receptor antagonist and 5HT₄ receptor agonist activity, and used as an antiemetic and gastroprokinetic since almost 50 years. Regulatory authorities issued restrictions and recommendations regarding long-term use of the drug at oral doses exceeding 10 mg 3-4 times daily because of the risk for development of tardive dyskinesia. The aim of our study was to review mechanism(s) of action and pharmacokinetic-pharmacodynamic properties of metoclopramide, as well as the risk of metoclopramide-induced tardive dyskinesia, factors that may change drug exposure in humans, and to summarize the clinical context for appropriate use of the drug.

METHODS

A PubMed, Google Scholar, and Cross Reference search was done using the key words and combined searches: drug-drug interaction, gastroparesis, metoclopramide, natural history, pharmacokinetics, pharmacodynamics, drug-drug interaction, outcome, risk factors, tardive dyskinesia.

KEY RESULTS

Data show that the risk of tardive dyskinesia from metoclopramide is low, in the range of 0.1% per 1000 patient years. This is far below a previously estimated 1%-10% risk suggested in treatment guidelines by regulatory authorities. High-risk groups are elderly females, diabetics, patients with liver or kidney failure, and patients with concomitant antipsychotic drug therapy, which reduces the threshold for neurological complications.

CONCLUSIONS & INFERENCES

The risk of tardive dyskinesia due to metoclopramide is far below approximated numbers in treatment guidelines. This risk and the influence of known risk factors should be considered when starting a course of metoclopramide for treatment of gastroparesis.

Single Dose Pharmacokinetics of Metoclopramide Oral Tablets Utilizing HPLC-UV Method

Background:

Metoclopramide is a potent dopaminergic antagonist utilized for treating gastrointestinal disorders. The aim of this study was to examine the pharmacokinetics of oral formulation of metoclopramide in the Pakistani volunteers.

Methods:

This open label, single dose, pharmacokinetic study was executed in non-smoking, 12 Pakistani healthy males, treated with a single 20 mg oral tablet dose of metoclopramide on test day. Maximum plasma concentration (Cmax), time to achieve Cmax (Tmax), and area under curve (AUC0-t) of metoclopramide were determined analyzing the serial blood samples using a validated HPLC-UV method.

Results:

The determined values of Cmax, Tmax, and AUC0-t of metoclopramide were 34.51 ± 4.91 ng/ml, 1.56 ± 0.18 and 273.88 ± 114.49 ng.h/ml, respectively.

Conclusion:

The results reveal that the findings of Pakistani individuals are slightly different when compared with the published data of other ethnic origins.

Comparison of the pharmacokinetics of a new 15-mg modified-release tablet formulation of metoclopramide versus a 10-mg immediate-release tablet: a single- and multiple-dose, randomized, open-label, parallel-group study in healthy Mexican male volunteers

BACKGROUND

Metoclopramide is a prokinetic and antiemetic agent.

OBJECTIVE

The goal of this study was to assess the pharmacokinetics of a new, modified-release metoclopramide tablet and compare it with an immediate-release tablet to obtain marketing approval from the Mexican regulatory agency.

METHODS

This was a single-center, randomized, open-label, parallel-group, single- and multiple-dose, pharmacokinetic study. Investigational products were administered to healthy Mexican male volunteers for 3 consecutive days: one 15-mg modified-release tablet every 12 hours or one 10-mg immediate-release tablet every 8 hours. Multiple blood samples were collected after the first and last doses of metoclopramide over a 24-hour period. Plasma metoclopramide concentrations were determined by using a validated HPLC method. Safety and tolerability were assessed by measurement of vital signs, clinical evaluations, and spontaneous reports from study subjects.

RESULTS

All 26 subjects were included in the analyses (mean [SD] age: 25 [6] years [range, 18-40 years]; body mass index, 23.44 [2.31] kg/m(2) [range, 18.26-27.49 kg/m2]). Peak plasma concentrations were lower (C(max), 33.13 [7.25] vs 46.04 [17.27] ng/mL after the first dose [P < 0.05]; C(max,ss), 48.60 [8.52] vs 75.23 [21.27] ng/mL after the last dose [P < 0.05]) and occurred later (P < 0.05) with the modified-release formulation. In terms of average plasma concentrations (C(avgτ), 20.98 [3.94] vs 23.38 [7.35] ng/mL after the first dose; C(avg,ss), 22.20 [5.64] vs 23.02 [7.77] ng/mL after the last dose), differences did not reach the level of statistical significance (P > 0.05). Four adverse events were reported in the test group (abdominal distention [n = 2], epigastric pain [n = 1], and somnolence [n = 1]), and 3 were reported in the reference group (epigastric pain [n = 1], diarrhea [n = 1], and hiccups [n = 1]).

CONCLUSIONS

This study in a sample of selected healthy Mexican male volunteers suggests that the metoclopramide15-mg modified-release tablets have features compatible with the slow-release formulation (lower C(max) and longer T(max)) compared with immediate-release tablets.

Classification of orally administered drugs on the World Health Organization Model list of Essential Medicines according to the biopharmaceutics classification system

Since its inception in 1995, the biopharmaceutical classification system (BCS) has become an increasingly important tool for regulation of drug products world-wide. Until now, application of the BCS has been partially hindered by the lack of a freely available and accurate database summarising solubility and permeability characteristics of drug substances. In this report, orally administered drugs on the Model list of Essential Medicines of the World Health Organization (WHO) are assigned BCS classifications on the basis of data available in the public domain. Of the 130 orally administered drugs on the WHO list, 61 could be classified with certainty. Twenty-one (84%) of these belong to class I (highly soluble, highly permeable), 10 (17%) to class II (poorly soluble, highly permeable), 24 (39%) to class III (highly soluble, poorly permeable) and 6 (10%) to class IV (poorly soluble, poorly permeable). A further 28 drugs could be provisionally assigned, while for 41 drugs insufficient or conflicting data precluded assignment to a specific BCS class. A total of 32 class I drugs (either certain or provisional classification) were identified. These drugs can be further considered for biowaiver status (drug product approval based on dissolution tests rather than bioequivalence studies in humans).

Kinetics of intravenous metoclopramide in patients with hepatic cirrhosis

The pharmacokinetics of metoclopramide has been studied after acute IV administration to 12 patients with hepatic cirrhosis (6 with and 6 without ascites) and 6 control subjects. The elimination half-life was significantly longer in patients (11.4 h and 9.9 h in those with and without ascites, respectively, vs 6.4 h in controls). Total plasma clearance was significantly lower in patients (0.29 and 0.36 l.kg-1.h-1 vs 0.52 l.kg-1.h-1 in controls). The differences between patients with and without ascites did not reach statistical significance. Reduction of functional hepatic blood flow in cirrhotic patients is the probable cause of the observed alteration in metoclopramide kinetics.

Pharmacokinetics of metoclopramide in patients with liver cirrhosis

The pharmacokinetics of metoclopramide were investigated after intravenous and oral administration in eight patients with severe alcoholic cirrhosis and in eight healthy volunteers. As a consequence of a 50% lower clearance (0.16 +/- 0.07 vs 0.34 +/- 0.09 l h-1 kg-1, plasma drug concentrations and the half-life of metoclopramide were greater in patients following both routes of drug administration. Volume of distribution (3.1 +/- 0.8 vs 3.4 +/- 1.2 l kg-1) and absolute bioavailability (79 +/- 19 vs 84 +/- 15%) were similar in the two groups. The adverse effects of metoclopramide observed in patients with marked hepatic impairment are likely to result from increased accumulation of the drug as a result of impaired clearance. Consequently a reduction in dose of 50% is recommended in patients with severe liver cirrhosis.

Effect of haemodialysis on metoclopramide kinetics in patients with severe renal failure

The kinetics of metoclopramide and the effects of haemodialysis on metoclopramide kinetics were examined in eight uraemic subjects 1 h and 24 h prior to the onset of dialysis. In spite of the relatively minor contribution of renal clearance to total body clearance in normals, metoclopramide kinetics were substantially altered in uraemia. The total body clearance was decreased by 2-4 fold, terminal elimination half-life proportionately increased, while the volume of distribution appeared to be unaffected compared with that previously demonstrated in normal healthy subjects. Haemodialysis does not appear to be effective in removing metoclopramide from the body and metoclopramide clearance subsequent to dialysis is unaltered. The kinetic parameters in the uraemic subjects are not significantly different between drug administrations 1 or 24 h prior to the time of onset of haemodialysis. Following kidney transplantation, in one subject, there appeared to be a rapid return to apparently normal kinetics from the uraemic state.