A 77 year old female has been taking chronic duloxetine 60 mg daily for neuropathy and depression. She has been experiencing increasing confusion, lower back pain, and painful urination. A urinalysis is performed and she is diagnosed with a urinary tract infection.
The primary provider elects to start a seven day course of ciprofloxacin to treat the UTI. Per Lexicomp, this interaction is listed as an “X” (i.e. do not use these medications together). When assessing any drug interaction, it is really important to understand more than “there is a drug interaction”. What we really want to know is what is going to happen (or likely to happen) if these drug are given together.
Ciprofloxacin is a potent CYP1A2 inhibitor. Duloxetine is significantly metabolized via this pathway. The end result of the duloxetine and ciprofloxacin drug interaction will be an increase in the systemic concentration of duloxetine.
So, now what? Do we reduce the dose? Do we hold duloxetine? Do we leave it alone and monitor for duloxetine adverse effects? Would your opinion be different if this patient was on 120 mg daily or 30 mg daily of duloxetine? It is always tough to make a blanket statement as each case should be assessed independently. The severity of the depression (or other diagnosis like neuropathy) history and length of Cipro should also be considered.
One final point, and question to think about in assessing drug interactions in general. Always remember to consider alternatives to the drug that might be causing the interaction. In this case, how many other possible alternatives might exist to treat the UTI and avoid messing with the duloxetine altogether?
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Eric Christianson, PharmD, BCPS, CGP
…much more efficient, safe, and effective to have just prescribed nitrofurantoin or sulfamethoxazole/trimethoprim as a first agent against a UTI.
Depends on what bug caused your UTI
I worry about macrobid since elderly have decreased CrCl and Bactrim for the same reason and additionally the hyperkalemia risk so I disagree with the above comment. They could try a single dose of fosfomycin though…
Duloxetine failed to receive US approval for stress urinary incontinence amid concerns over liver toxicity and suicidal events; however, it was approved for this indication in the UK, where it is recommended as an add-on medication in stress urinary incontinence instead of surgery…….The Cochrane study found evidence that duloxetine has increased side effects and reduced tolerability compared to other antidepressants. It thus did not recommend duloxetine as a first line treatment for major depressive disorder, given the high cost of duloxetine compared to off-patent -antidepressants and lack of increased efficacy.–Wikipedia
In view of this would it not be pertinant to have a second look at the use of (rather, the discontinuance of) Duloxetine before venturing into the selection of a suitable antibiotic to treat UTI in this elderly patient pre diagnosed and treated for neuropathic disorders?