Effect of chloroquine pre-treatment on the metoclopramide's pharmacokinetics after their co-administration

BACKGROUND

This study evaluated the pharmacokinetic interactions of orally administered chloroquine and metoclopramide.

METHODS

The study employed a randomized and two-phase cross-over design with four weeks washout plan. Twelve healthy male volunteers were shortlisted according to the set criteria and were administered with metoclopramide 10 mg PO, and chloroquine (a total of 1500 mg) at different intervals which were (500 mg at 0, 6, and 24 h). The concentration of chloroquine and metoclopramide in the blood samples was estimated using a validated HPLC-UV technique to affirm the maximum concentration (Cmax), time to reach Cmax (Tmax), and area under the curve (AUC).

RESULTS

Cmax, T1/2, and AUC of metoclopramide were increased up to 20, 10, and 47.8% respectively by the concomitantly administering Chloroquine. Chloroquine-treated phase showed increased values of Cmax (ng/ml), AUC (ng.h/ml), and T½ (h), i.e. 41.35 ± 1.61, 504.12 ± 66.25 and 5.72 ± 2.63, as compared to that Reference phase i.e. 34.52 ± 4.92, 341.14 ± 112.8, and 5.19 ± 1.14, respectively.

CONCLUSIONS

Chloroquine was found to attenuate CYP2D6 activity in healthy Pakistani male volunteers. Hence, patients that are prescribed with metoclopramide or other CYP2D6-substrate drugs require a dose adjustment when administered with chloroquine.

The efficacy of prophylactic metoclopramide in preventing nausea and vomiting in patients with acute pain treated with intravenous tramadol: a randomized double-blinded, placebo-controlled trial

OBJECTIVE

To examine the clinical efficacy of prophylactic metoclopramide in reducing the incidence of nausea and vomiting in emergency department (ED) patients with acute pain who were treated with intravenous tramadol.

RESULTS

We conducted a single-center randomized, double-blinded, placebo-controlled trial. A total of 99 ED patients presented with acute pain were recruited. Sixty-four patients were randomized, 31 patients in the treatment arm and 33 in the control arm. Overall, there were no significant differences in baseline characteristics between treatment arm and control arm. Only one patient within each arm reported having nausea symptom. No patients reported vomiting episode. There was no statistically significant difference in the proportion of patients with nausea or vomiting symptoms between the two groups (3.2% in the treatment arm vs. 3.0% in the control arm, p = 1.000). The administration of prophylactic metoclopramide may not provide additional benefit in reducing the occurrence of nausea and/or vomiting episode in ED patients with acute pain treated with intravenous tramadol. Trial registration Randomized clinical trial TCTR20220525001; registration date: 21 October 2021. Retrospectively registered.

Prophylactic antiemetics for adults receiving intravenous opioids in the acute care setting

BACKGROUND

Physicians often prescribe opioids for pain in the acute care setting. Nausea and vomiting are well-described adverse events, occurring in over one-third of patients. Prophylactic antiemetics may be one option to reduce opioid-associated nausea and vomiting. However, these medications also have their own adverse effects, so it is important to understand their efficacy and safety prior to routine use. This is a review of randomized controlled trials comparing prophylactic antiemetics versus placebo or standard care for preventing opioid-associated nausea and vomiting.

OBJECTIVES

To assess the effects of prophylactic antiemetics for nausea and vomiting in adults (aged 16 years or older) receiving intravenous opioids in the acute care setting.

SEARCH METHODS

We searched CENTRAL (the Cochrane Library), MEDLINE (OVID), Embase (OVID) from inception to January 2022, and Google Scholar (17 January 2022). We also searched the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) and screened reference lists.

SELECTION CRITERIA

We included randomized controlled trials of prophylactic antiemetics versus placebo or standard care in adults prior to receiving an intravenous opioid.

DATA COLLECTION AND ANALYSIS

Two review authors (MG, JNC) independently determined the eligibility of each study according to the inclusion criteria. Two review authors (MG, GDP) then independently extracted data, assessed risk of bias, and determined the certainty of evidence using GRADE. Our primary outcomes were the occurrence of nausea, vomiting, and adverse events. Secondary outcomes included nausea severity, number of vomiting episodes, and number of participants requiring antiemetic rescue therapy. We presented outcomes as risk ratios (RR) for dichotomous data (e.g. presence of vomiting, presence of nausea, number of participants requiring rescue medication, adverse events) and mean difference (MD) or standardized mean difference for continuous data (e.g. number of vomiting episodes, nausea severity) with 95% confidence intervals (CI).

MAIN RESULTS

We included three studies involving 527 participants (187 women and 340 men) with a mean age of 42 years.  All studies used intravenous metoclopramide (10 mg) as the intervention and a placebo for the comparator. No studies assessed any other antiemetic or compared the intervention to standard care. Compared to placebo, metoclopramide did not reduce vomiting (RR 1.18, 95% CI 0.26 to 5.32; low-certainty evidence) or nausea (RR 0.55; 95% CI 0.15 to 2.03; low-certainty evidence) and there was no difference in adverse events (RR 2.34, 95% CI 0.47 to 11.61; low-certainty evidence).  No data were available regarding the number of vomiting episodes. Metoclopramide did reduce the severity of nausea compared with placebo (MD -0.49, 95% CI -0.75 to -0.23; low-certainty evidence) but did not reduce the need for rescue medication (RR 1.86, 95% CI 0.17 to 20.16; low-certainty evidence).  Two studies were at unclear risk of bias for random sequence generation, one for blinding of outcome assessors, one for incomplete outcome data, and two for selective reporting. The studies were at low risk of bias for all remaining components.

AUTHORS' CONCLUSIONS

There was no evidence that prophylactic metoclopramide affected the risk of vomiting, nausea, or the need for rescue medication when provided prior to intravenous opioids in the acute care setting. There was a clinically insignificant difference in nausea severity when comparing prophylactic metoclopramide with placebo. Overall, the evidence was of low certainty. Future research could better delineate the effects of prophylactic antiemetics on specific populations, and new studies are needed to evaluate the use of other prophylactic antiemetic agents, for which there were no data.

Effect of clarithromycin pre-treatment on the pharmacokinetics of metoclopramide after their simultaneous oral intake

OBJECTIVE

The objective of this study was to assess the influence of enzyme suppression on the values of various pharmacokinetic factors of orally administered metoclopramide.

METHOD

This study was conducted in two phases and a 4-week duration was adopted for drug washout. This randomized study involved 12 healthy human volunteers who received a single oral dose of metoclopramide 20 mg. After the washout period, volunteers received clarithromycin 500 mg two times per day for consecutive 5 days. On test day (fifth day), a single oral dose of metoclopramide 20 mg was also given to the volunteers, and collection of blood samples was conducted at pre-decided time points. Various pharmacokinetic parameters such as C_max, T_max, and AUC_0-∞ of metoclopramide were determined by analyzing the blood samples using a validated HPLC-UV method.

RESULTS

Clarithromycin increased the mean values of C_max, AUC_0-∞, and T_1/2 of metoclopramide by 46%, 78.6%, and 9.8%, respectively.

CONCLUSION

Clarithromycin noticeably increased the concentration of plasma metoclopramide. This study's results provide in vivo confirmation of the CYP3A4 involvement in metoclopramide metabolism, in addition to CYP2D6. Therefore, metoclopramide pharmacokinetics may be clinically affected by clarithromycin and other potent enzyme inhibitors.

Evaluation of Pharmacokinetic Interaction of Cilostazol with Metoclopramide after Oral Administration in Human

BACKGROUND

Metoclopramide is mainly metabolized by CYP2D6, CYP3A4, CYP2C19, and CYP1A2 enzymes, while cilostazol is also metabolized by CYP3A4, CYP2C19, and CYP1A2 enzymes.

AIM

This study evaluates the effect of cilostazol on the pharmacokinetics of oral metoclopramide.

METHODS

This was a randomized, two-phase cross-over pharmacokinetic study separated by a 4-week wash-out time period, 12 healthy non-smoking volunteers received metoclopramide 20 mg as a single oral dose and after 4 weeks, cilostazol 100 mg twice daily for 4 days then with metoclopramide 20 mg on test day. Serial blood samples were analyzed by using a validated high-performance liquid chromatography-ultraviolet method to determine maximum plasma drug concentration (Cmax), time to reach (Tmax), and area under the curve (AUC0-∞) of metoclopramide.

RESULTS

Cilostazol increased the mean Cmax, AUC0-∞ and half-life (T1/2) of metoclopramide by 6%, 27% and by 0.79 %, respectively. In addition, Tmax of metoclopramide was delayed by cilostazol.

CONCLUSION

The results showed delayed Tmax of metoclopramide by cilostazol, which could lead to the conclusion that cilostazol affects the absorption of metoclopramide. Both drugs when necessary to administer together must not be administered at the same time especially when given in gastroparesis patients.