title: The evaluation of the diuretic action of parenteral formulations of metolazone.
abstract: OBJECTIVE
  This study was design to compare the diuretic and natriuretic effects of the 2 parenteral formulations of metolazone and the combination of these 2 formulations of metolazone with the parenteral administration of furosemide. Metolazone is an anthracrene acid derivate and manifests a dual diuretic effect on the proximal and distal tubule with a minimal kaluretic effect. It is currently only marketed in an orally administrable formulation, and this has limited its utility in critically ill patients. Metolazone given orally and furosemide given orally or parenterally are frequently administrated together when furosemide alone is clinically inadequate at producing a desired diuresis.
  
  
  METHODS
  Sprague Dawley male rats (400 to 450 g) were divided into groups to receive a parenteral formulation of metolazone or furosemide administrated separately intraperitoneally (IP) or administrated IP in combination with one another. Tris buffer-administered IP was used as a control vehicle comparator. The urine volume voided over the following 24 hours was collected, measured and analyzed for sodium content.
  
  
  RESULTS
  Vehicle (Tris buffer) caused 9 +/- 1 mL/d output of urine with a sodium [Na+] concentration of 194 +/- 41 micromol/L (n=6 per group). Metolazone 2 mg/kg resulted in 16 +/- 3 mL/d urine output and sodium [Na+] of 278 +/- 76 micromol/L (n=6 per group). Furosemide 2, 4, and 6 mg/kg resulted in a volume of urine 9 +/- 1, 14 +/- 2 and 17 +/- 2 mL/d and [Na+] micromol/L of 194 +/- 41, 206 +/- 108, and 229 +/- 91, respectively. Metolazone 4 mg/kg combined with furosemide 4 mg/kg resulted in a urine volume of 21 +/- 1 mL/d and [Na+] of 326 +/- 108 micromol/L.
  
  
  CONCLUSIONS
  Combining metolazone and furosemide can cause an increase in urine volume and sodium excretion. Metolazone administrated parenterally in combination with the parenteral administration of furosemide appears to have an important clinical potential.
authors.affiliation: Division of Clinical Pharmacology, Rush University Medical Center, Chicago, IL 60612, USA. ivanacvetanovic@yahoo.com
authors.forename: Ivana
authors.initials: I
authors.lastname: Cvetanovic
authors.forename: Vasant
authors.initials: V
authors.lastname: Ranade
authors.forename: Janos
authors.initials: J
authors.lastname: Molnar
authors.forename: Andrew
authors.initials: A
authors.lastname: Whelton
authors.forename: John
authors.initials: J
authors.lastname: Somberg
mesh_terms: D000818:Animals; D004231:Diuresis / Q000187:drug effects*; D004232:Diuretics / Q000008:administration & dosage / Q000494:pharmacology*; D004338:Drug Combinations; D005665:Furosemide / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007274:Injections, Intraperitoneal; D008297:Male; D008788:Metolazone / Q000008:administration & dosage / Q000494:pharmacology*; D009318:Natriuresis / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004232:Diuretics; D004338:Drug Combinations; D005665:Furosemide; D008788:Metolazone