Australia to adopt INNs

The Therapeutic Goods Administration (TGA) has announced that it will proceed with international harmonisation of drug names used in Australia from April 2016. For the past decade or so, since the United Kingdom moved to the World Health Organization’s International Nonproprietary Names (INNs), we’ve been in the anomalous situation of using former British Approved Names despite these no longer being used in the UK (nor listed in the British Pharmacopoeia). The TGA website has a list of affected drugs.

Some changes are trivial:

  • Substitution of “ph” with “f” (e.g. cefalexin, guaifenesin)
  • Substitution of “y” with “i” (e.g. amoxicillin, ciclosporin)
  • Substitution of “th” with “t” (e.g. indometacin)

Others are more significant (and will require dual-labelling for 3 years), for example:

  • Dosulepin (dothiepin)
  • Formoterol (eformoterol)
  • Furosemide (frusemide)
  • Glycopyrronium bromide (glycopyrrolate)
  • Hydroxycarbamide (hydroxyurea)
  • Lidocaine (lignocaine)

On the contentious subject of adrenaline vs epinephrine, the TGA has followed the UK practice where dual-labelling “adrenaline (epinephrine)” will be used indefinitely.

HbA1c now funded for diagnosis

From 1 November 2014, glycated haemoglobin (HbA1c) testing is now funded on the Medicare Benefits Schedule for the diagnosis of diabetes mellitus – MBS item 66841 (up to once every 12 months).

MBS item 66841

The Australian Diabetes Society and other international organisations have recommended since 2011 that an HbA1c ≥48 mmol/mol (≥6.5%) can be used to establish a diagnosis of diabetes.1 Until now this has been impracticable in Australia as it was only Medicare-funded for patients with established diabetes, however this new listing on the MBS provides clinicians with a more practical and efficient way to make the diagnosis.

Reference:
1. d’Emden M, et al. The role of HbA1c in the diagnosis of diabetes mellitus in Australia. Med J Aust 2012;197:220–1. (full text)

eGFR vs CrCl

Estimated glomerular filtration rate (eGFR) and creatinine clearance (CrCl) are often, incorrectly, used interchangeably when discussing renal function and drug dose adjustment.

Creatinine clearance, usually estimated using the 1976 Cockcroft-Gault formula rather than actually measured by (notoriously unreliable) 24-hour urine collection, has traditionally been used for drug dosing as it is relatively standardised despite overestimating renal function due to tubular secretion of creatinine. In addition to the usual caveats associated with basing renal function estimates on serum creatinine (acute illness, muscle mass, diet, etc), accuracy of the formula is limited by changes to serum creatinine assays and the rise in obesity since 1976.

Renal function is assessed nowadays using formula-derived eGFR (actual GFR is impracticable to measure routintely). Until recently this was usually calculated using the MDRD formula (1999), which has been well validated but has limited accuracy above 60 mL/min. Laboratories in Australia now report eGFR calculated using the superior CKD-EPI formula (2009). Although both of these formulae give better estimates of true renal function (GFR) than CrCl, they are both still based on serum creatinine with its associated caveats above.

Some studies have shown a reasonable concordance between CrCl (Cockcroft-Gault) and eGFR (MDRD) with respect to drug dosing,1 whereas others have noted significant differences.2–3 At the end of the day, CrCl and eGFR are not the same thing and prescribers should remain vigilant as to which measurement has been used to formulate dosage adjustment recommendations.

References:
1. Stevens LA, et al. Am J Kidney Dis 2009;54:3342
2. Wargo KA, et al. Ann Pharmacother 2006;40:124853
3. Park EJ, et al. Ann Pharmacother 2012;46:117487

Biotechnology descriptors

Whilst giving a presentation at grand rounds recently, I noted that approved names for biological medications in Australia are suffixed with a three-letter abbreviation – the “biotechnology descriptor” – to indicate the biotechnology production system used, e.g. insulin lispro (rbe).

The most common biotechnology descriptors are:

  • ghu – gene-activated human cell line
  • rbe – recombinant bacteria Escherichia coli
  • rch – recombinant Chinese Hamster ovary cell line
  • rmc – recombinant mouse cell line
  • rys – recombinant yeast Saccharomyces cerevisiae

Incidentally, I cringe whenever someone refers to this group of medications as “biologics” – an Americanism that has crept into the Australian medical lexicon. Australian English still retains the “-ical” ending (rather than shortening to “-ic” in American English), therefore we should continue to refer to these medications as “biologicals”.

A day in the life of a medical registrar

14 new patients post-take (1 DOA)
7am consultant rounds
Interviewed by the police
Discussion with an Assistant Coroner
Rescued from a difficult dilemma by one of the geriatricians (again)
Spoke with the hospital Director of Medical Services
AWOL patient urinating on the hospital front lawn
Challenging discussions with families about end-of-life issues
Asked for two consults at 4pm (because my consultant specifically wanted me to ask)
Somehow didn’t get shouted at for the late consults
Finished my ward round after-hours
Left the hospital at 7.30pm

… and very grateful for my fantastic intern Angela!

Leeches in modern medicine

Leeches have been used medicinally for centuries, with their most well-known role in the former practice of blood-letting. In modern medicine, however, the medicinal leech (Hirudo medicinalis) has found a niche role in plastic/reconstructive surgery where it can be used to reduce venous congestion and encourage microcirculation.

medicinal leeches

medicinal leeches

Specially prepared leeches are attached to the relevant part (e.g. at-risk surgical flap) and allowed to feed. Once gorged they detach themselves and are collected for re-use. Heparin wipes may be used at the bite site to prolong the therapeutic anticoagulation effect.

medicinal leeches

At our centre, collected leeches are prepared for re-use by placing in them saline – apparently this encourages them to regurgitate their initial feed. Subsequent feeds are less effective, so after 1-2 feeds the leech is “retired” using concentrated saline and flushed down a sluice sink.