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

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.

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.

Influence of Rifampicin Pre-treatment on the In vivo Pharmacokinetics of Metoclopramide in Pakistani Healthy Volunteers Following Concurrent Oral Administration

BACKGROUND

Metoclopramide is metabolized by various cytochrome P450 (CYP) enzymes such as CYP3A4, CYP1A2, CYP2D6, CYP2C9, and CYP2C19. Rifampicin is a non-selective inducer of P-glycoprotein (P-gp) and CYP enzymes such as CYP3A4 and others.

OBJECTIVE

This study was aimed at the evaluation of rifampicin's enzyme induction effect on the pharmacokinetic parameters of orally administered metoclopramide.

METHOD

This randomized, single-blind, two-phase cross-over pharmacokinetic study separated by a 4-week washout period was conducted at a single center in Pakistan. It involved twelve Pakistani healthy male volunteers (nonsmokers) divided into two groups. In the reference phase, each volunteer received a single oral dose of 20 mg metoclopramide (Maxolon 10 mg, GlaxoSmithKline, Pakistan), while in the rifampicin-treated phase, each volunteer received 600 mg rifampicin once daily for 6 days through oral route. On day 6, metoclopramide (20 mg) was administered 2 hours after the last pretreatment dose of rifampicin. The serial blood samples were collected on predetermined time points (0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 14, and 18 h) and analyzed using a validated HPLC method for the determination of pharmacokinetic parameters, i.e. Cmax, Tmax, and AUC0-∞ of metoclopramide. The whole study was monitored by an unblinded clinician for the purpose of volunteer's health safety.

RESULTS

All the volunteers participated in the study until the end. Twelve healthy Pakistani males having mean age 26.0 (range 20.6-34.1) years and body mass index 25.1 (range 16.2-31.5) kg/m2 were included in this study after taking written informed consent. Rifampicin significantly (P<0.05) decreased the mean Cmax, AUC0-∞ and T1/2 of metoclopramide by 35%, 68%, and 44%, respectively. The laboratory tests did not reveal any significant change in the biochemical, physical, hematological, or urinalytical values before and after metoclopramide treatment. None of the volunteers complained of any discomfort during the study.

CONCLUSION

Rifampicin noticeably decreased the concentration of plasma metoclopramide. These results give in vivo confirmation of the CYP3A4 involvement in the metoclopramide metabolism, in addition to CYP2D6. Therefore, metoclopramide pharmacokinetics may be clinically affected by rifampicin and other potent enzyme inducers.

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.