Massive theophylline dosing in a heavy smoker receiving both phenytoin and phenobarbital.
OBJECTIVE
To report unusually high theophylline dosing requirements in a smoker receiving concomitant therapy with phenytoin and phenobarbital.


METHODS
Single case report.


METHODS
517-bed, university teaching hospital.


METHODS
29-year-old woman with newly diagnosed asthma, heavy smoking history, and a seizure disorder.


RESULTS
The additive influence of smoking, phenytoin, and phenobarbital greatly increased the theophylline dosing requirements. Doses of up to 4 g/d (59 mg/kg/d) were required to achieve adequate symptomatic relief of her asthma as well as to provide therapeutic serum theophylline concentrations.


CONCLUSIONS
Multiple polymorphisms may additively influence theophylline metabolism and exceptionally large theophylline doses may be required in some patients who smoke and are comedicated with phenytoin and phenobarbital.
Nicholson
J P
JP
Department of Pharmacy, University Medical Center, Jacksonville, FL 32209.
Basile
S A
SA
Cury
J D
JD
D000328:Adult; D001249:Asthma / Q000188:drug therapy; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D010634:Phenobarbital / Q000627:therapeutic use*; D010672:Phenytoin / Q000627:therapeutic use*; D012640:Seizures / Q000188:drug therapy; D012907:Smoking / Q000378:metabolism*; D013806:Theophylline / Q000008:administration & dosage*
D010672:Phenytoin; D013806:Theophylline; D010634:Phenobarbital