title: Trends in metformin utilisation and dose appropriateness in Australia.
abstract: OBJECTIVE
  The study aimed to (1) determine the trends in the utilisation of metformin in Australia, (2) determine the appropriateness of metformin dosing in an Australian teaching hospital and (3) gather the opinions of prescribers on the relationship between metformin dose and renal function.
  
  
  METHODS
  National prescription data between 1990 and 2012 were accessed. A retrospective audit (2008-2012) of metformin doses and patient renal function (20 % random sample of all in-patients prescribed metformin) was conducted at St Vincent's Hospital (SVH), Sydney. Prescribers of metformin were interviewed (semi-structured; consultants at SVH) or surveyed (Australian endocrinologists) to gather their understanding of metformin dosing in relation to renal function.
  
  
  RESULTS
  Metformin utilisation increased fivefold nationally between 1995 and 2012. Metformin tended to be under-dosed in SVH patients with normal renal function (83.5 %) and over-dosed in patients with impaired renal function (estimated glomerular filtration rate (eGFR) <30 mL/min, 50 %). Consultants indicated that metformin doses needed to be reduced in renal impairment. Most endocrinologists (61 %) were comfortable prescribing metformin down to eGFRs around 30 mL/min.
  
  
  CONCLUSIONS
  The use of metformin increased greatly over the period of the study. Metformin is prescribed frequently for patients with eGFR values below the minimal level approved in the product label (60 mL/min). While prescribers expressed their understanding of the need to reduce metformin doses in patients with renal impairment, we found that metformin doses were higher than appropriate in patients with impaired renal function. Metformin may be used safely when renal function is poor provided dosage is appropriately reduced.
authors: Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Darlinghurst, New South Wales, 2010, Australia.|St Vincent's Hospital Clinical School, Faculty of Medicine, University of New South Wales, Sydney, Australia.
authors: J
authors: J
authors: Moon
authors: Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Darlinghurst, New South Wales, 2010, Australia.|School of Medical Science, Faculty of Medicine, University of New South Wales, Sydney, Australia.
authors: S S
authors: SS
authors: Kumar
authors: Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Darlinghurst, New South Wales, 2010, Australia.|School of Medical Science, Faculty of Medicine, University of New South Wales, Sydney, Australia.
authors: G G
authors: GG
authors: Graham
authors: Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Darlinghurst, New South Wales, 2010, Australia.|Centre for Health Systems & Safety Research, Australian Institute of Health Innovation, Faculty of Medicine, Macquarie University, Sydney, Australia.
authors: M T
authors: MT
authors: Baysari
authors: Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Darlinghurst, New South Wales, 2010, Australia.|School of Medical Science, Faculty of Medicine, University of New South Wales, Sydney, Australia.
authors: K M
authors: KM
authors: Williams
authors: Diabetes and Metabolism Research Division, Garvan Institute of Medical Research, Sydney, Australia.
authors: W
authors: W
authors: Chen
authors: Diabetes and Metabolism Research Division, Garvan Institute of Medical Research, Sydney, Australia.
authors: A
authors: A
authors: Viardot
authors: Diabetes and Metabolism Research Division, Garvan Institute of Medical Research, Sydney, Australia.
authors: J R
authors: JR
authors: Greenfield
authors: Department of Clinical Pharmacology and Toxicology, St Vincent's Hospital, Darlinghurst, New South Wales, 2010, Australia. r.day@unsw.edu.au.|St Vincent's Hospital Clinical School, Faculty of Medicine, University of New South Wales, Sydney, Australia. r.day@unsw.edu.au.|School of Medical Science, Faculty of Medicine, University of New South Wales, Sydney, Australia. r.day@unsw.edu.au.
authors: R O
authors: RO
authors: Day
mesh_terms: D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000503:physiopathology; D004363:Drug Utilization / Q000639:trends*; D005919:Glomerular Filtration Rate; D006784:Hospitals, Teaching / Q000639:trends; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D008687:Metformin / Q000008:administration & dosage / Q000627:therapeutic use*; D009517:New South Wales; D051437:Renal Insufficiency / Q000188:drug therapy / Q000503:physiopathology
chemical_list: D007004:Hypoglycemic Agents; D008687:Metformin
keywords: Dosing appropriateness; Metformin; Renal function