Co-prescriptions with itraconazole and fluconazole as a signal for possible risk of drug-drug interactions: a four-year analysis from Italian general practice.
OBJECTIVE
To determine the prevalence of concomitant use of drugs potentially responsible for interactions among itraconazole and fluconazole users in general practice.


METHODS
During the years 1999-2002, we obtained information from the 'Health Search Database', (HSD) an Italian general practice research database. Among a total sample of 457 672 eligible patients, we included those aged >16 years, and whose diagnoses could be classified as mycosis. Itraconazole and fluconazole users were then selected. A potentially drug-drug interaction (DDI) occurred when the use of concomitant drugs were recorded within +/-30 days from the date of the first azoles prescription. Interacting drugs were classified according to the summary of product characteristics (SPC) as provided by the Italian Pharmaceutical Repertory (REFI).


RESULTS
From 18 323 cases of mycosis, we selected 4843 itraconazole and 1446 fluconazole users. Potentially interacting drugs were prescribed in 8.7% of itraconazole and 6.1% of fluconazole users. For itraconazole, calcium channel blockers were the most common interacting drugs (3.3%), followed by statins (1.7%) and clarithromycin (1.3%), whereas gestoden + ethynylestradiol (2.5%) and benzodiazepines (1.8%) resulted as the most common interacting drugs among fluconazole users.


CONCLUSIONS
Data indicate a relevant prevalence of concomitant use of medications potentially leading to drug interactions among azoles users. Because of the wide use of these medications in general practice, they should be used with clinical monitoring in view of their known side effects as well as their potential risk for drug interaction.
Galatti
Laura
L
Department of Clinical and Experimental Medicine and Pharmacology, University of Messina, Torre Biologica-Policlinico Universitario, Via Consolare Valeria-Gazzi, Messina, Italy. lgalatti@unime.it
Mazzaglia
Giampiero
G
Greco
Antonella
A
Sessa
Emiliano
E
Cricelli
Claudio
C
Schito
Gian Carlo
GC
Nicoletti
Giuseppe
G
Spina
Edoardo
E
Caputi
Achille P
AP
D000293:Adolescent; D000328:Adult; D000368:Aged; D000935:Antifungal Agents / Q000627:therapeutic use*; D019992:Databases as Topic / Q000706:statistics & numerical data; D004347:Drug Interactions; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D004363:Drug Utilization / Q000706:statistics & numerical data; D005194:Family Practice / Q000706:statistics & numerical data*; D005260:Female; D015725:Fluconazole / Q000627:therapeutic use*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D017964:Itraconazole / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009181:Mycoses / Q000188:drug therapy* / Q000453:epidemiology; D016017:Odds Ratio; D019338:Polypharmacy; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D018570:Risk Assessment; D013997:Time Factors
D000935:Antifungal Agents; D017964:Itraconazole; D015725:Fluconazole