title: Comparative retention rates and long-term tolerability of new antiepileptic drugs.
abstract: OBJECTIVE
  Retention rates of five new anti-epileptic medications (AEDs) were compared in order to evaluate their long-term tolerability and efficacy.
  
  
  METHODS
  We acquired the retention data on levetiracetam (LEV), lamotrigine (LTG), oxcarbazepine (OXC), topiramate (TPM), and zonisamide (ZNS) from the electronic database. The data included patient's age, gender, seizure type, current and previous medications, dosage, main reasons for discontinuation, and duration of therapy. The retention rates of these AEDs were evaluated at 4, 12, 24, 52, and 104 weeks.
  
  
  RESULTS
  A total of 828 new AED exposures were obtained (LEV=196, LTG=251, OXC=97, TPM=156, ZNS=128) from patients with partial or generalized epilepsy. At 2 years, retention rate was highest with LTG (74.1%), followed by ZNS (60.2%), OXC (58.8%), LEV (53.6%), and TPM (44.2%). When these AEDs were discontinued, it was mainly due to inefficacy (29.5%) and sedating side-effects (20.5%), and commonly within 6 months into therapy. Several important AED specific side-effects leading to discontinuation were identified, including behavioral or irritability from LEV, rash from LTG and OXC, nausea from OXC and ZNS, hyponatremia from OXC, and kidney stones from TPM and ZNS.
  
  
  CONCLUSIONS
  Comparing retention rates of new AEDs can provide useful insight into their tolerability and efficacy. This study showed highest retention rate with LTG, which was significantly different from ZNS (p=0.0025), LEV (p<0.0001), OXC (p=0.0024), and TPM (p<0.0001). Beside ineffectiveness, other leading causes of discontinuation were adverse behavioral effects with LEV, rash with LTG and OXC, and sedation for TPM and ZNS.
authors.affiliation: Department of Neurology, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ, USA. sschung@chw.edu
authors.forename: Steve
authors.initials: S
authors.lastname: Chung
authors.forename: Norman
authors.initials: N
authors.lastname: Wang
authors.forename: Nicole
authors.initials: N
authors.lastname: Hank
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000927:Anticonvulsants / Q000627:therapeutic use*; D004827:Epilepsy / Q000188:drug therapy*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance / Q000706:statistics & numerical data*
chemical_list: D000927:Anticonvulsants