Ciprofloxacin, when given to patients previously anticoagulated with warfar
in, can occasionally cause an exaggerated hypoprothombinemic response and b
leeding diatheses, Two such cases encountered at our institution are presen
ted and data is combined with 64 cases reported to the Food and Drug Admini
stration's (FDA) Spontaneous Reporting System (SRS) database, which include
d all cases reported from 1987 through 1997. Of 66 total cases the median a
ge was 72 (range 36-94). The mean time to detection of the coagulopathy fol
lowing the ciprofloxacin challenge was 5.5 days (n = 50). Hospitalization w
as reported in 15 cases, bleeding in 25 cases, and death in one case. The m
edian prothrombin time (PT) and International Normalized Ratio (INR) was 38
.0 (n = 13) and 10.0 (n = 23), respectively. The mean number of medications
taken was 6.5 (n = 45). The mean time to correction was significantly shor
ter between the treated (2.5 days) and the untreated (4.0 days) groups (P <
0.008). The ciprofloxacin-warfarin coagulopathy occurred most commonly in
patients in their seventh decade and in those who require polypharmacy, Act
ive treatment of the coagulopathy results in more rapid resolution than obs
ervation alone. Clinicians should be aware of the potential bleeding compli
cations that can occur with the ciprofloxacin-warfarin drug-drug interactio
n. (C) 2000 Wiley-Liss, Inc.