title: Ethyl propionate is more effective and less cytotoxic than methyl tert-butyl ether for topical gallstone dissolution.
abstract: OBJECTIVE
  Ethyl propionate and isopropyl acetate were identified as gallstone solvents with more favorable physicochemical properties than the currently used solvent methyl tert-butyl ether (MTBE). In this study, their efficacy and toxicity were compared.
  
  
  METHODS
  To compare efficacy, matched stones from 33 patients were subjected to dissolution with each solvent. To evaluate cytotoxicity, jejunal segments of the anesthetized rat were exposed to each solvent or saline; the segments were then perfused with markers for active absorption and passive permeability.
  
  
  RESULTS
  For 23 gallstone sets that dissolved completely with all three solvents, the average dissolution time was shorter with ethyl propionate (38 +/- 8 minutes) than with MTBE (60 +/- 13 minutes) (P = 0.03) or isopropyl acetate (55 +/- 12 minutes) (P < 0.001). Four stones did not dissolve with ethyl propionate, seven with MTBE, and eight with isopropyl acetate. After 2 minutes of exposure to the solvents, the dry weight of the segments decreased by 36% after MTBE but was unchanged after the other two solvents (P < 0.001). MTBE caused more inhibition of active absorption than the other solvents (P < 0.001) and a greater increase in passive permeation (P < 0.03).
  
  
  CONCLUSIONS
  Ethyl propionate and isopropyl acetate are less toxic to the intestinal mucosa than MTBE, and ethyl propionate is more effective for gallstone dissolution.
authors.affiliation: Department of Medicine, University of Connecticut School of Medicine, Farmington 06030, USA.
authors.forename: S F
authors.initials: SF
authors.lastname: Zakko
authors.forename: J C
authors.initials: JC
authors.lastname: Scirica
authors.forename: M C
authors.initials: MC
authors.lastname: Guttermuth
authors.forename: J
authors.initials: J
authors.lastname: Dodge
authors.forename: J J
authors.initials: JJ
authors.lastname: Hajjar
mesh_terms: D000085:Acetates / Q000627:therapeutic use* / Q000633:toxicity*; D000818:Animals; D002769:Cholelithiasis / Q000628:therapy*; D006801:Humans; D066298:In Vitro Techniques; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000187:drug effects*; D007583:Jejunum / Q000187:drug effects*; D008297:Male; D008738:Methyl Ethers / Q000627:therapeutic use* / Q000633:toxicity*; D011422:Propionates / Q000627:therapeutic use* / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012997:Solvents / Q000627:therapeutic use* / Q000633:toxicity*; D013997:Time Factors
chemical_list: D000085:Acetates; D008738:Methyl Ethers; D011422:Propionates; D012997:Solvents; C069372:isopropyl acetate; C043243:methyl tert-butyl ether; C069373:ethyl propionate