Evidence from one study suggests that ciprofloxacin increases theserum levels of pentoxifylline, and may increase incidence ofadverse effects. In some clinical studies ciprofloxacin has beenused to boost levels of pentoxifylline.
Because patients taking pentoxifylline and ciprofloxacin often complained of headache, possibility of a pharmacokinetic interaction was studied in 6 healthy subjects. The study showed that ciprofloxacin 500mg daily for 3 days increased peak serum levels of a single 400mg dose of pentoxifylline by almost 60 % (from 114.5 to 179.5 nanograms/mL), and increased AUC by 15%. All 6 subjects complained of a frontal headache (See reference number 1).
The evidence suggests that ciprofloxacin inhibits metabolism of pentoxifylline (a xanthine derivative) by liver
Information on this interaction and its clinical relevance is limited. The author of pharmacokinetic study suggests that, if drugs need to be used together, dosage of pentoxifylline should be halved (See reference number 1). In absence of other information, if a short-course of ciprofloxacin is required in a patient taking pentoxifylline, this may be a sensible precaution. Alternatively, because increase in AUC was minor, it may be sufficient to recommend a reduction in pentoxifylline dose only in those who experience adverse effects (e.g. nausea,headache). Note that ciprofloxacin has been used to boost pentoxifylline levels in studies investigating possible therapeutic value of pentoxifylline’s ability to inhibit various cytokines. For example,ciprofloxacin 500mg twice daily was used with pentoxifylline 800mg three times daily for up to one year in patients with myelodysplastic syndrome (See reference number 2).
Cleary JD. Ciprofloxacin (CIPRO) and pentoxifylline (PTF): a clinically significant drug interaction. Pharmacotherapy (1992) 12,259–60.
Raza A,Qawi H, Lisak L, Andric T, Dar S, Andrews C, Venugopal P, Gezer S, Gregory S,Loew J, Robin E, Rifkin S, Hsu W-T, Huang R-W. Patients with myelodysplastic syndromesbenefit from palliative therapy with amifostine, pentoxifylline, and ciprofloxacin with or without dexamethasone. Blood (2000) 95, 1580–87.