title: Cross-reactivity between darunavir and trimethoprim-sulfamethoxazole in HIV-infected patients.
abstract: OBJECTIVE
  Both darunavir (DRV) and trimethoprim-sulfamethoxazole (TMP-SMX) carry a sulfonamide moiety and a warning for this cross-reactivity is given in the label of DRV. The aim of this study was to investigate the potential cross-reactivity between both drugs.
  
  
  METHODS
  Retrospective cohort study with a nested case-control study.
  
  
  METHODS
  HIV-infected patients that received DRV-containing antiretroviral therapy at any time during the period of their HIV infection were included. Patients with no history of TMP-SMX use were excluded. The incidence of a DRV allergy, according to the Naranjo probability scale, was investigated in patients with an allergy to TMP-SMX compared with those without such an allergy. In order to identify possible risk factors associated with a DRV allergy among patients allergic to TMP-SMX, a nested case-control study was subsequently performed.
  
  
  RESULTS
  A total of 405 patients were included, of whom 79 (17.5%) had a history of allergy to TMP-SMX. A DRV allergy was seen in four patients (5.1%) with a TMP-SMX allergy compared with four (1.2%) without a TMP-SMX allergy (P = 0.05). Patients with a TMP-SMX allergy were at higher risk for a DRV allergy (odds ratio 4.29; 95% confidence interval, 1.05-17.56). No additional risk factors for a DRV allergy among patients allergic to TMP-SMX were identified in the nested case-control study.
  
  
  CONCLUSIONS
  Although DRV allergy is uncommon, making cross-reactivity with TMP-SMX a rare clinical problem, it appears to exist more often in the background of a TMP-SMX allergy.
authors.affiliation: aDepartment of Internal Medicine and Infectious Diseases, University Medical Center Utrecht, Utrecht bDepartment of Internal Medicine, Onze Lieve Vrouwe Gasthuis, Amsterdam cDepartment of Clinical Pharmacy, University Medical Center Utrecht, Utrecht, The Netherlands.
authors.forename: Bianca S
authors.initials: BS
authors.lastname: Buijs
authors.forename: Guido E
authors.initials: GE
authors.lastname: van den Berk
authors.forename: Charlotte P
authors.initials: CP
authors.lastname: Boateng
authors.forename: Andy I
authors.initials: AI
authors.lastname: Hoepelman
authors.forename: Erik M
authors.initials: EM
authors.lastname: van Maarseveen
authors.forename: Joop E
authors.initials: JE
authors.lastname: Arends
mesh_terms: D000328:Adult; D000368:Aged; D019380:Anti-HIV Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D000069454:Darunavir / Q000008:administration & dosage / Q000493:pharmacokinetics*; D004342:Drug Hypersensitivity / Q000453:epidemiology*; D004347:Drug Interactions; D005260:Female; D015658:HIV Infections / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D019380:Anti-HIV Agents; D000890:Anti-Infective Agents; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D000069454:Darunavir