Published: November 2005

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Watching Briefs - Dec 2005

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Prescriber Update 26(2): 21-22
November 2005

Medsafe Pharmacovigilance Team

Update on COX-2 inhibitors
Leflunomide - watch for respiratory symptoms
Isotretinoin - contraception is critical
Reminder about obtaining patient consent

Miconazole oral gel interaction with warfarin
Update on Salamol inhalers

Update on COX-2 inhibitors

Medsafe has recently concluded the updating of the data sheets for the following COX-2 inhibitors: Arcoxia® (etoricoxib), Celebrex® (celecoxib), Dynastat® (parecoxib), Mobic® (meloxicam) and Prexige® (lumiracoxib). These changes were recommended by the Medicines Adverse Reactions Committee (MARC), and are intended to best manage the cardiovascular risks of the COX-2 inhibitors and to identify those select patients in whom appropriate use may be warranted. Key points for prescribers are:

  • The decision to prescribe a selective COX-2 inhibitor should only be made if non-pharmacological interventions and simple analgesic therapies have been tried and found to lack analgesic efficacy or have unacceptable adverse effects in the individual patient; and after assessment of the individual patient's overall risks.
  • As the cardiovascular risks of the selective COX-2 inhibitors may increase with dose and duration of exposure, the shortest duration possible and the lowest effective daily dose should be used.
  • Patients on long-term treatment should be reviewed regularly, such as every three months, with regards to efficacy, risk factors and ongoing need for treatment.
  • Use in the peri-operative period is contraindicated in patients undergoing cardiac or major vascular surgery; and contraindicated in patients who have previously had a myocardial infarction or stroke.
  • Patients with significant risk factors for cardiovascular events should only be treated with a COX-2 inhibitor after careful consideration of the patient's overall risk and the potential risks and benefits of alternative analgesic therapies.
  • Prescribers should inform the individual patient of the possible increased risks when prescribing a COX-2 inhibitor for patients at high risk of cardiovascular adverse events.

Prescribers are additionally encouraged to continue reporting any suspect adverse reaction of clinical concern relating to the use of COX-2 inhibitors. These reports will assist Medsafe and MARC in the ongoing safety monitoring of these medicines.

Leflunomide - watch for respiratory symptoms

Leflunomide (Arava®) is a disease-modifying anti-rheumatic agent indicated for the treatment of rheumatoid arthritis. It is often used in conjunction with methotrexate. The Centre for Adverse Reactions Monitoring (CARM) has received seven reports of pneumonitis occurring in patients taking leflunomide together with methotrexate.  Clinical trial data indicate that pneumonitis can also occur with leflunomide alone. This disorder is characterised by dyspnoea, hypoxia and lung infiltrates. Initial symptoms in the CARM reports were various combinations of dyspnoea, cough, fever, lethargy, weight loss and influenza-like symptoms followed by rapid progression to acute respiratory compromise. Early recognition is important as pneumonitis can be life-threatening or lead to persistent disability. Patients should be informed about initial warning symptoms so that these can be investigated immediately and the suspect medicines discontinued.

Isotretinoin - contraception is critical

Information on this subject has been updated. Read the most recent information.

Isotretinoin is highly teratogenic, which means that effective contraception is essential for all women of childbearing age (including those with a history of infertility) for whom isotretinoin is a treatment option. Women should be counselled about the risk of teratogenicity so they know it is critical that they not become pregnant while on isotretinoin. Prescribers must also exclude pregnancy prior to starting isotretinoin, and inform women to continue using contraception for one month after stopping isotretinoin.

Reminder about obtaining patient consent

Prescribers are reminded of their obligation to obtain informed consent from patients when making treatment decisions. This requirement forms part of the Code of Health and Disability Services Consumers' Rights 1996, which states that every consumer has the right to be fully informed of the risks and benefits of the proposed treatment. The Code also states that consumers have the right to receive the information they need to make an informed choice or give informed consent.

If a clinician is considering prescribing an unapproved medicine (i.e. a medicine that has not been assessed by Medsafe against regulatory standards for safety, efficacy and quality), the onus is on the prescriber to satisfy themself that the medicine is of appropriate safety, quality and efficacy before deciding to prescribe it.

Medsafe considers that, in order for clinicians to comply with the Code, during the consultation the patient should be advised about 1) the unapproved status of the medicine; and 2) the information that led the clinician to decide why that particular unapproved medicine is the most appropriate treatment for the patient. It is only after this information has been communicated that the patient's informed consent for treatment with an unapproved medicine is considered to have been obtained.

Miconazole oral gel interaction with warfarin

Information on this subject has been updated. Read the most recent information.

Prescribers are reminded of the potentially severe interaction between miconazole oral gel (Daktarin® oral gel) and warfarin.  Clinically significant increases in the international normalised ratio (INR) of patients stabilised on warfarin have been reported following concomitant use of miconazole oral gel, due to systemic absorption.  Warfarin patients who are given miconazole oral gel should be monitored for change in anticoagulant effect and the dose of warfarin adjusted, if necessary. As miconazole oral gel can be purchased without a prescription, both pharmacists and prescribers should inform patients taking warfarin of the potential for this interaction.

Update on Salamol inhalers

Testing of the Salamol® brand of salbutamol inhalers has shown that blockages can be prevented by washing the device once every week. Remove the metal canister and rinse the plastic mouthpiece under warm water for 30 seconds, shake to remove excess water then leave it to air dry (overnight if possible). Reassemble the inhaler device once dry. Patients may wish to keep a spare inhaler handy for use while the cleaned inhaler is drying.

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