Lack of methemoglobinemia with flutamide.
OBJECTIVE
To determine whether the nonsteroidal antiandrogenic drug flutamide is a clinically relevant inducer of methemoglobinemia in patients with prostatic cancer.


METHODS
Fifty consecutive outpatients with prostatic cancer stage D2 entered the study (age 71.1 +/- 7.3 y). Five patients were lost to follow-up; the remaining 45 patients received the recommended oral dose of flutamide 250 mg three times daily. Total hemoglobin (Hb) and methemoglobin (Met-Hb) concentrations were measured on varying days using an ultraviolet/visible-spectrophotometric method with an intra- and interday variability < 8%. In 12 patients, Met-Hb was analyzed before initiating flutamide therapy and after therapy was begun.


RESULTS
On average, 2.6 venous blood samples per patient were analyzed with a mean Met-Hb concentration of 1.9% of total Hb. Mean concentrations of > or = 3% were detected in only six patients (13%). The data from 12 patients evaluated before and after initiating flutamide therapy were without significantly different changes. During the study period, no clinical signs of methemoglobinemia were reported or observed.


CONCLUSIONS
This study found no clinically relevant increase of Met-Hb concentrations in elderly patients with prostatic cancer during chronic treatment with flutamide. However, clinicians should be aware of the very rare possibility of flutamide-induced methemoglobinemia.
Schulz
M
M
Center for Drug Information and Pharmacy Practice, ABDA-Federal Union of German Associations of Pharmacists, Eschborn, Germany. M.Schulz@abda.aponet.de
Schmoldt
A
A
Donn
F
F
Becker
H
H
D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000009:adverse effects / Q000627:therapeutic use*; D005485:Flutamide / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008706:Methemoglobin / Q000187:drug effects / Q000378:metabolism; D008708:Methemoglobinemia / Q000139:chemically induced*; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000473:pathology; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D005485:Flutamide; D008706:Methemoglobin