Vol.59 No.1 January 2011
A case of decreased plasma phenytoin concentration following combined therapy with ciprofloxacin
1)Department of Pharmacy, Japan Labour Health and Welfare Organization Osaka Rosai Hospital, 1179-3 Nagasone, Kita-ku, Sakai, Osaka, Japan
2)Department of Pharmacy, Japan Labour Health and Welfare Organization Chugoku Rosai Hospital
Abstract
We report a case of decreased plasma phenytoin(PHT) concentration in PHT administration attributed to interaction from combined ciprofloxacin(CPFX) use.
A 49-year-old man administered the antiepileptic drug PHT (250 mg/day) for status epilepticus at 16.5 μg/mL recently underwent artery embolization of the upper pole of the spleen during surgery, followed by an infection treated with CPFX. Despite steady progress, he had generalized convulsions on 10 day when the plasma PHT concentration was 1.02 μg/mL. We immediately discontinued CPFX and attempted to control convulsions. After discontinuation of CPFX, the plasma PHT concentration increased from 5.75 and 8.18 μg/mL to 10.06 μg/mL. The free PHT concentration was about 10% in all samples. Urinary pH increased slightly from 6 to 6.5.
Based on similar cases reported abroad, our subject very likely experienced decreased plasma PHT concentration due to combined CPFX use. This suggests the importance of monitoring plasma PHT and obtaining the optimal concentration during concomitant CPFX use in clinical settings.
Key word
phenytoin, ciprofloxacin, side effect
Received
May 14, 2010
Accepted
September 29, 2010
Jpn. J. Chemother. 59 (1): 25-28, 2011
