(Aust Prescr 1998;21:60-3)
Letters, which may not necessarily be published in full, should be restricted to not more than 250 words. When relevant, comment on the letter is sought from the author. Due to production schedules, it is normally not possible to publish letters received in response to material appearing in a particular issue earlier than the second or third subsequent issue.
Editor, - I would like to draw your readers' attention to the discrepancy between the product information for moclobemide and paroxetine.
The product information for moclobemide reads `There are limited data ... to support the safety of changing from low to moderate doses of serotonin reuptake inhibitors (SRI) to moclobemide 300 mg/day by ceasing the SRI on one day and starting moclobemide on the next.'
The product information for paroxetine reads `MAO inhibitors should not be introduced within 2 weeks of therapy with paroxetine.'
These appear to be in conflict.
Julian Fidge
Graduate medical student
University of Queensland
Herston, Qld
The Editor comments:
Both statements quoted in Julian Fidge's letter are correct and not in
conflict. There are limited data to support the safety of changing from low
to moderate doses of selective serotonin reuptake inhibitors (SSRIs) to moclobemide
300 mg/day by ceasing the SSRI one day and starting moclobemide on the next.
The product information for paroxetine, and for other SSRIs, refers only to
potential interactions with (irreversible non-selective) monoamine oxidase
inhibitors (MAOIs). There is no reference in the current Australian product
information for any SSRI regarding interactions (if any) with reversible selective
inhibitors of monoamine oxidase A in general, or moclobemide in particular.
Moclobemide is more restricted in actions and is a different monoamine oxidase inhibitor to the old MAOIs. The letter highlights the confusion which may arise when lumping medicines into classes. It may not be entirely clear which medicines are, or are not, members of a specific class. Furthermore, the effects of one drug in the class may not occur with the other members of that class.
For advice on changing antidepressant treatment, see the advice
in the `Psychotropic Drug Guidelines' Edition 3, 1995 of the Victorian Medical
Postgraduate Foundation Therapeutics Committee. (This does not include advice
on subsequently registered antidepressants.)
Editor, - Since my intern days, I have always used one needle to draw up a medication into a syringe (except for plastic ampoules, where I fit the syringe nozzle directly), then replaced this needle with a second one for the actual injection. Since talking to doctors who use the one needle for both purposes, I am unable to confidently justify my `wastage'. Is there a risk of a glass fragment (or rubber, in the case of the rubber-sealed ampoules) attaching itself to the needle tip?
Justin Coleman
General Practitioner
Sumner Park, Qld
Dr Paul Nisselle, the Australasian Secretary of the Medical
Protection Society, comments:
The Medical Protection Society does not have any cases in its international
database of a patient asserting damage resulting from using one needle to both
aspirate medication from an ampoule and inject the medication into the patient.
The rationale, as I understand it, for using two needles when aspirating from a rubber-sealed ampoule is:
• the needle will be significantly blunted having perforated the rubber seal, and hence the subsequent injection will be more traumatic to the patient than when a fresh, perfectly sharp needle is used
• the outside of the needle may be contaminated going through the rubber, and that contamination could then be transferred to the patient if the same needle is used
• most rubber-sealed ampoules were used for multi-dose administration, and hence it was thought that changing to a second needle reduced the possibility of patient-to-patient transmission of contamination or infection.
Generally speaking, multi-dose ampoules have been abandoned, and hence the latter point does not arise.
With a glass-topped ampoule, I see no particular reason for using one needle to draw up the medication and another to inject it. If there are any single-dose, rubber-topped ampoules, then continuation of using two needles may well be appropriate in that circumstance, as there will still be the blunt needle problem.
However, to repeat, I know of no instance where a patient
has come to harm and sought compensation as a result of using only one needle
to aspirate and then inject medication from a single-dose ampoule.
Editor, - I am writing to you in response to Dr David Sharpe's question to the PBAC regarding the quantity of sumatriptan tablets supplied by pharmacists under the Pharmaceutical Benefits Scheme (PBS) (Aust Prescr 1997;20:87). As a pharmacist, I would like to bring the following points to Dr Sharpe's, as well as your other readers', attention.
It is ironic that Dr Sharpe's question should be published in an issue of Australian Prescriber accompanied by a report of 3 deaths due to myocardial infarction in patients taking sumatriptan (in one case the prescription was for 12 tablets at a time).1 These unfortunate incidents point to the critical level of care necessary in prescribing and dispensing such drugs and, at the very least, should discourage doctors from prescribing larger quantities of drugs such as sumatriptan.
At the same time however, Dr Sharpe seems to be unaware of the structure and the regulations governing supply of medicines under the PBS by pharmacists. The $5.20 per sumatriptan prescription represents the dispensing charge per PBS item of $4.34 plus a 10% mark up on cost price. This is a professional fee approved and set by the government. On the other hand, most pharmacists these days have a good idea of most of their patients' medication history and do not merely function as suppliers of medicines. The fee charged for prescriptions in many instances includes various value-added services such as provision of Consumer Medicines Information, information on drug interactions and, in the case of drugs such as sumatriptan, possible discussion with patients and their doctors regarding the latest adverse reaction reports.
I believe pharmacists are entitled to their $4.34 professional
fee!
Rick Samimi
Pharmacist
Neutral Bay, N.S.W.
Reference
1. Fatal outcomes after sumatriptan. Aust Adverse Drug
Reactions Bull 1997;16:15.
Bioequivalence of Coumadin and Marevan
Editor, - The debate about the existence of two brands of warfarin has centred around the bioequivalence of the two products.1,2 We have noticed a difference in bioavailability of up to 26% between brands of warfarin in one individual in a comparative study.3 No such study has been performed in Australia; however, to cover the possibility, the PBAC has recommended a warning note accompany PBS listings for warfarin brands and strengths.2
The Boots Company has suggested that a lack of testing of these products does not imply that they are not bioequivalent, but that caution should be exercised if brand substitution occurs. Our experience with a single patient indicates that the brands are not bioequivalent. The patient was on a dose of 4 mg of warfarin, initially provided by 1 x 1 mg, 1 x 3 mg Marevan, and had an INR = 2.7. Upon completion of that supply, the patient was given Coumadin (2 x 2 mg) and subsequently presented with an INR = 4.4. After questioning, we established that the patient was well and that brand substitution had occurred. The Coumadin was stopped and replaced with Marevan and the INR returned to an acceptable level. It was fortunate that the initial INR was not higher as the brand substitution could easily have placed the patient at risk of haemorrhage. It is reasonable to suggest from this patient that the brands are not bioequivalent. There is a report of similar instability in 15 patients who had their brand of warfarin substituted.4
As brand substitution is not allowed for warfarin products on the Pharmaceutical Benefits Scheme, hospital and community pharmacists should be wary about generic prescriptions and involve themselves in educating doctors and patients. Not only should they check which brand the patient is currently on, but also stress to the patient the importance of staying on that particular brand, in order to avoid possible variations in anticoagulant status.
V. Williams
Haematology Department
R. Vining
Pharmacy Department
Women's and Children's Hospital
Adelaide, S.A.
References
1. Healy DF. Warfarin tablets [letter]. Aust Prescr 1996;19:6-7.
2. Fry FK. Warfarin tablets [letter]. Aust Prescr 1997;20:33.
3. Muller FO, Steyn JM, Hundt HK, Luus HG. Warfarin bio-availability: a comparison of 4 products. S Afr Med J 1988;74:566-7.
4. Richton-Hewett S, Foster E, Apstein CS.
Medical and economic consequences of a blinded oral anticoagulant brand change
at a municipal hospital. Arch Intern Med 1988;148:806-8.
Current concepts in the management of cardiac arrest
Editor, - I read Dr John Holmes' `Current concepts in the management of cardiac arrest' and saved the wall chart (Aust Prescr 1997;20:41-5 and reprinted as insert to Aust Prescr 1997, Vol. 20 No. 4). Thank you for this excellent article and publication.
I would share an experience that relates to the decision to stop treatment. Many years ago, on a footpath in the city,I came across a man who, while jogging, had a cardiac arrest. With an assistant, we applied CPR for 40 minutes before the arrival of an intensive care ambulance crew who were prepared to abandon this man. After having oxygen and sodium bicarbonate, he sat up, was loaded into the ambulance and taken to hospital. I heard no more until some 3 months later.
On a Sunday morning, he came to my house to thank me for my perseverance and said that he had some further cardiac arrests in the hospital and was now about to return to his work as a civil engineer. I understand that `one swallow does not a summer make'. My concern is that, with the technologicalisation of our world, statistics will come to totally dominate everything that we do.
Throughout the CPR, this man, although his perfusion status clearly had deteriorated, maintained reactive pupils. Yet, in spite of my pointing this out to the otherwise very well-trained ambulance officers, they decided that more than 20 minutes without technological assistance was enough to declare someone dead.
On this rather slim level of experience, I would nonetheless still take exception to the statement `Cardiac arrest with no return of spontaneous circulation for greater than 30 minutes is usually hopeless'. I would certainly emphasise that withdrawal of treatment could be considered, but not in the absence of a clear clinical assessment. For example, if the neurological reactivity is still present, then maybe not abandoning hope at this stage is still indicated.
L. Handsjuk
Psychiatrist
Richmond, Vic.
Dr John L. Holmes, the author of the article, comments:
The issue of cessation of resuscitative efforts in cardiac arrest is always
difficult. Basic cardiac life support (i.e. cardiopulmonary resuscitation alone)
provides a circulatory output of only 500-750 mL/minute of relatively hypoxaemic
blood. This can maintain cerebral and myocardial viability for no more than
a few minutes. Whilst there have been several anecdotal reports of prolonged
cardiopulmonary resuscitation resulting in successful outcomes, in such cases
there may well have been cardiac activity and low grade spontaneous circulation
which is not easily detectable in the absence of physiological monitoring.
Dr Handsjuk rightly points out that resuscitation should be continued if there
is any evidence of ongoing neurological activity and reactive pupils are certainly
indicative of brain stem perfusion. However, resuscitation should be ceased
if, despite advanced cardiac life support interventions for 20-25 minutes,
the pupils have remained fixed and dilated and throughout the resuscitation
there has been a definite absence of spontaneous circulation.
This should be a positive clinical decision and is predicated on the knowledge
that, given the above criteria, outcomes are universally dismal.
Editor, - I would like to make a comment regarding dicloxacillin, which was listed in `New drugs' (Aust Prescr 1998;21:25-7).
With regard to adverse effects, I have recently been asked to see two patients having difficulty achieving adequate warfarinisation after taking dicloxacillin.
I realise that not all adverse effects can be listed in a summary of a new drug. However, I believe that the prolonged warfarin antagonism that occurs with drugs such as this should be brought to the attention of prospective users of a new drug.
John Gallo
Haematologist
Liverpool, N.S.W.
The Editor comments:
Dr Gallo is correct to highlight the interaction between warfarin and dicloxacillin.
As it is not possible to mention all the adverse effects of new drugs in a
brief comment, readers are always advised to consult the product information
before prescribing. The interaction is included in the product information
for dicloxacillin, but is not specifically mentioned in the product information
Editor, - Dr Joanne Hayes' letter to the Pharmaceutical Benefits Advisory Committee (`Your questions to the PBAC' Aust Prescr 1998;21:19) concerned a patient under psychiatric care who needed increased quantities of benzodiazepines. I have a similar patient.
I thought the response from the PBAC was inadequate because it did not solve Dr Hayes' problem. Are they saying we will turn a blind eye to your illegal back dating or forward dating of prescriptions in this situation?
There must be a better solution than the PBAC response. I would not have thought there would be an enormous number of patients, under the care of a psychiatrist, requiring 50 mg of diazepam a day on a long-term basis in Australia.
I would have thought a reasonable compromise situation might be that patients, under the care of a psychiatrist, requiring diazepam in a dose greater than 25 mg daily should be able to have an appropriate authority prescription.
Larry Light
General Practitioner
Altona, Vic.
Editor, - Dr Hayes' letter (`Your questions to the PBAC' Aust Prescr 1998;21:19) raises several points that the reply from the PBAC did not acknowledge.
• Although no doubt Dr Hayes' patient benefits greatly from her presence, and the talk that a general practitioner visit generates (the `soft end' of good medicine that non-clinicians seldom, and the bean-counters never, understand), on the face of it, Dr Hayes is acting as a deliverer of scripts for a drug ordered by someone else. Not only could this be seen as a somewhat demeaning role, but she may be exposed, at the psychiatrist's behest, to charges of over-servicing and inappropriate prescribing.
• If the PBAC cannot see its way to making special arrangements with general practitioners for such a case, at least it could make one with specialists. It would then fall to the specialist to explain the necessity for the unusual dosage, and the general practitioner's prescribing pattern would not be distorted on the pharmaceutical watchdogs' dossier. It would also release the general practitioner to make visits required by clinical, not bureaucratic, necessity.
• Much benzodiazepine use, according to the PBAC, was `inappropriate'. On page 4 of the same issue, the prescribing of cerebral vasodilators is called `undesirable'. Who is the judge of these things? Specialists in the relevant fields seem quite happy to prescribe both. Is an old person, with something lacking in his brain so that his nights are hellish and sleepless, more undesirably `dependent' on a sleeping pill (oxazepam is the present favourite) than a diabetic dependent upon insulin? If I ever get to that stage (and cannot afford a draught of vintage, cooled a long age in the deep-delved earth), I hope my general practitioner will have the compassion to do a bit of `inappropriate' prescribing.
Alasdair Livingston
Surgeon
Mitcham, S.A.
