Can Reglan (Metoclopramide) be prescribed to a patient taking Fluconazole, Azathioprine (Imuran), Tacrolimus, Prednisone, Buprenorphine, Montelukast (Singular), Senna, Metoprolol, Gabapentin, and Fluticasone (Flonase)?

Can Reglan Be Prescribed With This Medication Regimen?

Yes, Reglan (metoclopramide) can be prescribed to this patient, but requires careful monitoring for QT prolongation when combined with metoprolol, and dose adjustment of tacrolimus may be necessary due to fluconazole's interaction with the immunosuppressant. 1

Key Drug Interaction Considerations

Critical Interaction: Fluconazole and Tacrolimus

• Fluconazole is a potent CYP3A4 inhibitor that significantly increases tacrolimus levels, requiring close monitoring of tacrolimus blood concentrations 1
• Clinical data demonstrates fluconazole can cause up to a 9.1-fold increase in dose-normalized tacrolimus trough levels, necessitating an 87% reduction in tacrolimus dosing 2
• Oral fluconazole has more significant impact on tacrolimus levels than intravenous administration 2
• Tacrolimus therapeutic drug monitoring is essential when adding metoclopramide to this regimen, as the patient is already at risk for altered tacrolimus exposure from fluconazole 3

Moderate Interaction: Fluconazole and Prednisone

• Fluconazole co-administration with prednisone represents one of the most frequent moderate-severity interactions (25.3% of cases in hospitalized patients) 4
• While potential interactions are common, clinical consequences are rare - a study of 199 admissions found only 4 adverse drug events from fluconazole, with none definitively caused by drug-drug interactions 4

Metoprolol Considerations

• Metoprolol combined with metoclopramide requires monitoring for additive effects on cardiac conduction, particularly bradycardia 1
• Both agents can affect cardiac rhythm; metoclopramide's contraindications include use with caution in patients on medications affecting cardiac conduction 1
• The beta-blocker metoprolol is not metabolized by CYP3A4, so fluconazole does not affect its levels 5

No Significant Interactions Expected

• Gabapentin, senna, montelukast (Singulair), fluticasone (Flonase), and buprenorphine have no clinically significant interactions with metoclopramide based on their metabolic pathways 6, 5
• Azathioprine (Imuran) does not interact with metoclopramide through CYP450 pathways 5

Metoclopramide-Specific Precautions

Contraindications to Verify

• Rule out pheochromocytoma, seizure disorder, GI bleeding, and GI obstruction before prescribing metoclopramide 1
• These are absolute contraindications that must be excluded

Expected Adverse Effects

• Monitor for restlessness, drowsiness, diarrhea, muscle weakness, and dystonic reactions 1
• Dystonic reactions are particularly important to counsel patients about, especially in younger patients

Monitoring Strategy

When adding metoclopramide to this regimen:

• Check tacrolimus trough levels within 3-5 days of starting metoclopramide, as the patient is already on fluconazole which significantly affects tacrolimus metabolism 3, 2
• Monitor heart rate and blood pressure due to combined effects of metoprolol and metoclopramide 1
• Assess for signs of tacrolimus toxicity (nephrotoxicity, neurotoxicity, hyperglycemia) given the fluconazole interaction 3
• Consider that fluconazole effects on tacrolimus may persist for 161 days or more after discontinuation, requiring ongoing dose adjustments 2

Clinical Bottom Line

The primary concern is not metoclopramide itself, but rather the existing fluconazole-tacrolimus interaction that requires vigilant monitoring 2. Metoclopramide can be safely added with appropriate monitoring of tacrolimus levels and cardiac parameters 1, 4. The combination of multiple immunosuppressants (tacrolimus, azathioprine, prednisone) with fluconazole already places this patient at high risk for drug interactions, but metoclopramide does not substantially increase this risk 4, 5.