title: A comparison of active ingredients and preservatives between brand name and generic topical glaucoma medications using liquid chromatography-tandem mass spectrometry.
abstract: BACKGROUND
  This work compares the concentration of active ingredients and preservatives in commonly used brand name versus generic glaucoma medications.
  
  
  METHODS
  Active ingredient and benzalkonium chloride (BAK) concentrations in brand name latanoprost and dorzolamide-timolol were each compared to two generic counterparts using liquid chromatography-mass spectrometry at baseline and after exposure to 25°C and 50°C for 30 days. Micro flow imaging was used to quantify particulate material greater than one micron in diameter.
  
  
  RESULTS
  Brand name formulations contained active ingredients and BAK in concentrations that were generally in agreement with their package inserts at baseline. The two generic formulations of latanoprost contained baseline levels of active ingredients that were 10% greater than their labeled value. Generic latanoprost formulations had significant loss of active ingredient concentration after exposure to 25°C and 50°C for 30 days. Both generic and brand name dorzolamide-timolol appeared relatively resistant to degradation. BAK concentrations remained stable at 25°C but decreased in some bottles at 50°C. Bottles of both generic medications had higher levels of particulate matter compared to brand name versions.
  
  
  CONCLUSIONS
  Exposure to temperatures at the high end of the labeled value may lead to a significant decrease in concentration of active ingredients in generic formulations that could influence clinical efficacy. Re-evaluation of intraocular pressure lowering efficacy may be indicated in glaucoma patients switching from brand name to generic formulations.
authors: University of Colorado Hospital Eye Center, Department of Ophthalmology, Aurora, CO 80045, USA. Malik.Kahook@gmail.com
authors: Malik Y
authors: MY
authors: Kahook
authors: Robert D
authors: RD
authors: Fechtner
authors: L Jay
authors: LJ
authors: Katz
authors: Robert J
authors: RJ
authors: Noecker
authors: David A
authors: DA
authors: Ammar
mesh_terms: D000959:Antihypertensive Agents / Q000032:analysis*; D001548:Benzalkonium Compounds / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004338:Drug Combinations; D004340:Drug Contamination; D004355:Drug Stability; D004356:Drug Storage; D016568:Drugs, Generic / Q000737:chemistry*; D005901:Glaucoma / Q000188:drug therapy; D000077338:Latanoprost; D055553:Prescription Drugs / Q000737:chemistry*; D011310:Preservatives, Pharmaceutical / Q000032:analysis*; D011461:Prostaglandins F, Synthetic / Q000032:analysis*; D013449:Sulfonamides / Q000032:analysis*; D053719:Tandem Mass Spectrometry; D013876:Thiophenes / Q000032:analysis*; D013999:Timolol / Q000032:analysis*
chemical_list: D000959:Antihypertensive Agents; D001548:Benzalkonium Compounds; D004338:Drug Combinations; D016568:Drugs, Generic; D055553:Prescription Drugs; D011310:Preservatives, Pharmaceutical; D011461:Prostaglandins F, Synthetic; D013449:Sulfonamides; D013876:Thiophenes; C479140:dorzolamide-timolol combination; D000077338:Latanoprost; D013999:Timolol