Safety profile of oxcarbazepine: results from a prescription-event monitoring study.
OBJECTIVE
To monitor safety of oxcarbazepine, prescribed in primary care in England, using prescription-event monitoring (PEM).


METHODS
Postmarketing surveillance using observational cohort technique of PEM. Exposure data were obtained from dispensed British National Health Service prescriptions issued by general practitioners (GPs) March 2000-July 2003. Demographic, drug utilization, and clinical event data were collected from questionnaires posted to GPs at least 6 months after first prescription date for each patient. Incidence densities (IDs) (number of first reports per 1,000 patient-months of treatment) were calculated and differences for events reported in month 1 (ID(1)) and months 2-6 (ID(2-6)) (99% confidence intervals) were examined for changes in event rates. Follow-up and causality assessment of medically significant events were undertaken.


RESULTS
The cohort comprised 2,243 patients [mean age 40.4 years; range 2-99 years; standard deviation (SD) 18.8; 46.3% (n = 1,038) male]. Most frequently reported primary indications were epilepsy, convulsion (n = 1,111; 49.5%, n = 209; 9.3%, respectively). GPs recorded 932 reasons for stopping medication in 698 (31.1%) patients; most frequent clinical reason "drowsiness/sedation" (n = 57; 2.5% of cohort). Clinical events (excluding indication) associated with starting treatment (lower 99% CI > 0) included: "drowsiness/sedation" (ID(1)-ID(2-6) = 14.2), "nausea/vomiting" (ID(1)-ID(2-6) = 13.0), and dizziness (ID(1)-ID(2-6) = 11.6). Events followed up and assessed as probably related to oxcarbazepine use included rash (7 of 11) and hyponatremia (15 of 38).


CONCLUSIONS
There were no serious adverse drug reactions reported during this study. Results of the study should be taken in context with other epidemiologic studies.
Drug Safety Research Unit, Southampton, United Kingdom. yvonne.buggy@dsru.org
Yvonne
Y
Buggy
Deborah
D
Layton
Carole
C
Fogg
Saad A W
SA
Shakir
D000293:Adolescent; D000328:Adult; D016907:Adverse Drug Reaction Reporting Systems / Q000706:statistics & numerical data*; D000368:Aged; D000369:Aged, 80 and over; D002220:Carbamazepine / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D011307:Drug Prescriptions / Q000706:statistics & numerical data; D004363:Drug Utilization; D064420:Drug-Related Side Effects and Adverse Reactions; D004739:England / Q000453:epidemiology; D004827:Epilepsy / Q000188:drug therapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D000078330:Oxcarbazepine; D010821:Physicians, Family / Q000706:statistics & numerical data*; D010818:Practice Patterns, Physicians' / Q000706:statistics & numerical data*; D011358:Product Surveillance, Postmarketing / Q000706:statistics & numerical data; D013222:State Medicine / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires
D002220:Carbamazepine; D000078330:Oxcarbazepine