title: Analogues of erectile dysfunction drugs: an under-recognised threat.
abstract: OBJECTIVE
  To investigate the problem of drug analogue adulteration in male erectile dysfunction health products.
  
  
  METHODS
  Survey of over-the-counter male erectile dysfunction health products available in convenience stores and pharmacies in Hong Kong.
  
  
  METHODS
  Tertiary referral centre for clinical toxicology analysis in Hong Kong.
  
  
  METHODS
  The pattern and extent of adulteration of male erectile dysfunction health products with sildenafil, tadalafil, and vardenafil as well as their structurally modified analogues.
  
  
  RESULTS
  Of 26 products studied, one (4%) was found to contain undeclared sildenafil, while 14 (54%) contained drug analogues of different kinds. The latter included acetildenafil, hydroxyacetildenafil, hydroxyhomosildenafil, and piperidenafil. The first three were analogues of sildenafil and the last was an analogue of vardenafil. One young patient presented with ataxia after taking an acetildenafil-containing product.
  
  
  CONCLUSIONS
  The positive rate of concealed drug analogues in male erectile dysfunction health products is alarmingly high. Such analogues are difficult to detect by ordinary laboratory methods, and might be used in an attempt to evade regulatory inspection. Without going through the stringent drug testing process, the adverse effects of these chemicals remain largely unknown and unpredictable. Effective surveillance system and control measures are needed urgently. The medical profession and the public should be alerted to this under-recognised threat.
authors.affiliation: Hospital Authority Toxicology Reference Laboratory, Princess Margaret Hospital, Laichikok, Hong Kong.
authors.forename: W T
authors.initials: WT
authors.lastname: Poon
authors.forename: Y H
authors.initials: YH
authors.lastname: Lam
authors.forename: C K
authors.initials: CK
authors.lastname: Lai
authors.forename: Albert Y W
authors.initials: AY
authors.lastname: Chan
authors.forename: Tony W L
authors.initials: TW
authors.lastname: Mak
mesh_terms: D000328:Adult; D001259:Ataxia / Q000139:chemically induced*; D002243:Carbolines / Q000737:chemistry; D003625:Data Collection; D004340:Drug Contamination; D007172:Erectile Dysfunction / Q000188:drug therapy; D006723:Hong Kong; D006801:Humans; D007093:Imidazoles / Q000737:chemistry; D008297:Male; D004366:Nonprescription Drugs / Q000009:adverse effects / Q000737:chemistry*; D010726:Phosphodiesterase Inhibitors / Q000737:chemistry* / Q000592:standards; D010879:Piperazines / Q000737:chemistry; D028321:Plant Preparations / Q000009:adverse effects / Q000737:chemistry*; D011687:Purines / Q000737:chemistry; D011744:Pyrimidinones / Q000737:chemistry; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000737:chemistry; D000068581:Tadalafil; D014227:Triazines / Q000737:chemistry; D000069058:Vardenafil Dihydrochloride
chemical_list: D002243:Carbolines; D007093:Imidazoles; D004366:Nonprescription Drugs; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D028321:Plant Preparations; D011687:Purines; D011744:Pyrimidinones; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D000068677:Sildenafil Citrate; C526114:hydroxyacetildenafil; C526115:piperidenafil