Benzonatate and Mycophenolate Drug Interaction
No clinically significant drug interaction exists between benzonatate and mycophenolate (mycophenolate mofetil or mycophenolate sodium), and these medications can be safely co-administered without dose adjustment or additional monitoring beyond standard mycophenolate surveillance.
Evidence-Based Analysis
The available evidence does not identify any pharmacokinetic or pharmacodynamic interaction between benzonatate (a non-narcotic antitussive) and mycophenolate formulations:
Mycophenolate is primarily metabolized by uridine diphosphate glucuronosyltransferases (UGTs) in the liver, gastrointestinal tract, and kidney, with its major metabolite MPAG excreted renally and via bile through multi-drug resistance protein 2 (MRP-2). 1
Benzonatate undergoes local anesthetic action in the respiratory tract and does not significantly interact with hepatic enzyme systems or renal transporters that affect mycophenolate metabolism. [General Medicine Knowledge]
The documented drug interactions with mycophenolate involve agents that affect absorption (aluminum/magnesium antacids, cholestyramine, iron), purine metabolism (azathioprine), renal tubular secretion (acyclovir, ganciclovir), or hepatic UGT induction (high-dose corticosteroids). 2, 3
Known Mycophenolate Drug Interactions to Monitor
While benzonatate is safe to use, be aware of these clinically significant mycophenolate interactions:
Absorption inhibitors: Activated charcoal, aluminum/magnesium salts, cholestyramine, colesevelam, colestipol, and iron reduce mycophenolate absorption and should be separated by at least 2 hours. 2
Azathioprine co-administration is contraindicated due to increased purine metabolism inhibition. 2
Acyclovir and ganciclovir plasma concentrations increase when co-administered with mycophenolate, especially in renal impairment. 2
Hormonal contraceptive effectiveness may be reduced, requiring additional contraceptive methods. 2
Live vaccines should be avoided during mycophenolate therapy due to immunosuppression. 2
Standard Mycophenolate Monitoring Remains Unchanged
Continue routine mycophenolate monitoring regardless of benzonatate use:
CBC with differential weekly for the first month, twice monthly for months 2-3, then monthly for the remainder of the first year, followed by every 1-3 months indefinitely. 2
Comprehensive metabolic panel including renal and hepatic function every 1-3 months. 2
Monitor for signs of infection, fever, neurologic symptoms, or respiratory changes given mycophenolate's immunosuppressive effects. 2