title: [Original preparations versus generics--latanoprost: how similar is different?].
abstract: BACKGROUND
  To test the interchangeability of the commercially available (in Germany) latanoprost drugs and their generics respectively, the concentration of the active substance was tested. Guidelines of the European Medicines Agency postulate a sufficient bioequivalence, if the range of the agent is within 80-125% of the original drug.
  
  
  METHODS
  All compounds of latanoprost were procured registered. The concentration of latanoprost and benzalkoniumchloride was measured by high-performance liquid chromatography (HPLC) in a validated reference labroratory for 23 generics. In addition, the mean volume of drops and the pH of the formulation were measured. The packaging label and the readability of the enclosed information leaflet were checked.
  
  
  RESULTS
  All products contained less than 50 μg/ml latanoprost. The deviating reduction of the active substance (mean: - 7.39%, ± 2.8%) was accompanied by fluctions of the eyedrops' mass (mean: 0.03 g, ± 0.002 g). The concentration of benzalkonium chloride was mostly increased (median: 5.45%, min: - 2.5%, max: 11.5%). The pH of the original drug and the generics (median 6.78, min: 6.62, max: 6.81) was similar to the original drug, but was significantly different from an unpreserved formulation (pH 7.18). Due to type size, the packaging leaflet was illegible for humans with impaired vision.
  
  
  CONCLUSIONS
  Before prescribing generics in ophthalmology, different factors have to be considered, which might influence the amount of IOP lowering in effect. In the absence of healthcare research it is still unclear, how different bottle forms of eyedrops--such as appearance (e.g. Cyrillic characters) or pressure point (administration)--reduce the adherence of glaucoma patients.
authors.affiliation: Department für Augenheilkunde, Universitäts-Augenklinik, Universitätsklinikum Tübingen, Schleichstr. 12, 72076, Tübingen, Deutschland, martin.leitritz@med.uni-tuebingen.de.
authors.forename: M A
authors.initials: MA
authors.lastname: Leitritz
authors.forename: H-P
authors.initials: HP
authors.lastname: Lipp
authors.forename: B
authors.initials: B
authors.lastname: Voykov
authors.forename: F
authors.initials: F
authors.lastname: Ziemssen
mesh_terms: D000959:Antihypertensive Agents / Q000032:analysis / Q000737:chemistry; D004353:Drug Evaluation, Preclinical; D004348:Drug Labeling / Q000145:classification*; D016568:Drugs, Generic / Q000032:analysis* / Q000737:chemistry*; D005858:Germany; D000077338:Latanoprost; D011461:Prostaglandins F, Synthetic / Q000032:analysis* / Q000737:chemistry*; D013810:Therapeutic Equivalency
chemical_list: D000959:Antihypertensive Agents; D016568:Drugs, Generic; D011461:Prostaglandins F, Synthetic; D000077338:Latanoprost