title: Patch testing and cross sensitivity study of adverse cutaneous drug reactions due to anticonvulsants: A preliminary report.
abstract: OBJECTIVE
  To evaluate the utility of patch test and cross-sensitivity patterns in patients with adverse cutaneous drug reactions (ACDR) from common anticonvulsants.
  
  
  METHODS
  Twenty-four (M:F = 13:11) patients aged 18-75 years with ACDR from anticonvulsants were patch tested 3-27 mo after complete recovery using carbamazepine, phenytoin, phenobarbitone, lamotrigine, and sodium valproate in 10%, 20% and 30% conc. in pet. after informed consent. Positive reactions persisting on D3 and D4 were considered significant.
  
  
  RESULTS
  Clinical patterns were exanthematous drug rash with or without systemic involvement (DRESS) in 18 (75%), Stevens-Johnsons syndrome/toxic epidermal necrolysis (SJS/TEN) overlap and TEN in 2 (8.3%) patients each, SJS and lichenoid drug eruption in 1 (4.2%) patient each, respectively. The implicated drugs were phenytoin in 14 (58.3%), carbamazepine in 9 (37.5%), phenobarbitone in 2 (8.3%), and lamotrigine in 1 (4.7%) patients, respectively. Twelve (50%) patients elicited positive reactions to implicated drugs; carbamazepine in 6 (50%), phenytoin alone in 4 (33.3%), phenobarbitone alone in 1 (8.3%), and both phenytoin and phenobarbitone in 1 (8.33%) patients, respectively. Cross-reactions occurred in 11 (92%) patients. Six patients with carbamazepine positive patch test reaction showed cross sensitivity with phenobarbitone, sodium valproate and/or lamotrigine. Three (75%) patients among positive phenytoin patch test reactions had cross reactions with phenobarbitone, lamotrigine, and/or valproate.
  
  
  CONCLUSIONS
  Carbamazepine remains the commonest anticonvulsant causing ACDRs and cross-reactions with other anticonvulsants are possible. Drug patch testing appears useful in DRESS for drug imputability and cross-reactions established clinically.
authors.affiliation: T N Shiny, Vikram K Mahajan, Karaninder S Mehta, Pushpinder S Chauhan, Ritu Rawat, Rajni Sharma, Department of Dermatology, Venereology and Leprosy, Dr. R. P. Govt. Medical College, Kangra, Himachal Pradesh 176001, India.
authors.forename: T N
authors.initials: TN
authors.lastname: Shiny
authors.affiliation: T N Shiny, Vikram K Mahajan, Karaninder S Mehta, Pushpinder S Chauhan, Ritu Rawat, Rajni Sharma, Department of Dermatology, Venereology and Leprosy, Dr. R. P. Govt. Medical College, Kangra, Himachal Pradesh 176001, India.
authors.forename: Vikram K
authors.initials: VK
authors.lastname: Mahajan
authors.affiliation: T N Shiny, Vikram K Mahajan, Karaninder S Mehta, Pushpinder S Chauhan, Ritu Rawat, Rajni Sharma, Department of Dermatology, Venereology and Leprosy, Dr. R. P. Govt. Medical College, Kangra, Himachal Pradesh 176001, India.
authors.forename: Karaninder S
authors.initials: KS
authors.lastname: Mehta
authors.affiliation: T N Shiny, Vikram K Mahajan, Karaninder S Mehta, Pushpinder S Chauhan, Ritu Rawat, Rajni Sharma, Department of Dermatology, Venereology and Leprosy, Dr. R. P. Govt. Medical College, Kangra, Himachal Pradesh 176001, India.
authors.forename: Pushpinder S
authors.initials: PS
authors.lastname: Chauhan
authors.affiliation: T N Shiny, Vikram K Mahajan, Karaninder S Mehta, Pushpinder S Chauhan, Ritu Rawat, Rajni Sharma, Department of Dermatology, Venereology and Leprosy, Dr. R. P. Govt. Medical College, Kangra, Himachal Pradesh 176001, India.
authors.forename: Ritu
authors.initials: R
authors.lastname: Rawat
authors.affiliation: T N Shiny, Vikram K Mahajan, Karaninder S Mehta, Pushpinder S Chauhan, Ritu Rawat, Rajni Sharma, Department of Dermatology, Venereology and Leprosy, Dr. R. P. Govt. Medical College, Kangra, Himachal Pradesh 176001, India.
authors.forename: Rajni
authors.initials: R
authors.lastname: Sharma
keywords: Anticonvulsant hypersensitivity syndrome; Carbamazepine; Drug patch test; Drug rash with eosinophilia with or without systemic involvement; Lamotrigine; Phenobarbitone; Phenytoin; Sodium valproate; Stevens-Johnsons syndrome; Toxic epidermal necrolysis