NPC Archive Item: November Drug Safety Update from MHRA/CHM

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12 November 2009

The MHRA and CHM have published the November edition of Drug Safety Update (DSU). Highlights include:

  • Orciprenaline (Alupent®) will be withdrawn from the UK market over the coming year, due to its unfavourable risk-benefit profile.
  • A reminder about the reporting arrangements for suspected adverse reactions to swine flu antivirals and vaccines, and discusses reports received for the antivirals so far.
  • Patients receiving bisphosphonates for cancer are at greater risk of jaw osteoneocrosis than patients receiving bisphosphonates for other conditions.
  • Narrow therapeutic index of colchicine and its toxicity in overdose
  • Movement disorders in children treated with vigabatrin for infantile spasms.
  • A ‘Hot topics’ article discusses the current legal situation regarding mixing of medicines, particularly for parenteral administration by and at the request of non-medical prescribers.
  • Updates to the patient information leaflets of all statins, and a clarification of advice about aspirin use given in oseltamivir▼ patient information leaflets.

Drug Safety Update (DSU) is an essential read for everyone whose professional practice involves medicines. It is published every month in electronic format only.

Orciprenaline (Alupent®) withdrawal
Orciprenaline is a non-selective, short-acting beta-agonist. It is significantly less effective than salbutamol in the extent and duration of bronchodilation that it achieves. It is also associated with a high risk of cardiac side effects, mainly palpitations and tachycardia, which occur before maximum bronchodilation is achieved because of its non-selectivity. The MHRA is, therefore, working with the manufacturer to achieve a planned voluntary withdrawal of orciprenaline over the next year. The product will continue to be available for several months, but it is recommended that patients are switched to a more selective beta-agonist at the earliest opportunity.

Adverse reactions to swine flu antivirals and vaccines
As we blogged recently, the MHRA has established a safety monitoring programme for swine flu vaccines to capture, evaluate, and monitor suspected adverse drug reactions (ADRs). Members of the public and healthcare professionals should report any suspected adverse reactions to pandemic swine flu vaccines or antiviral medicines used for the treatment or prevention of swine flu through the dedicated online reporting website. Since many patients who receive one of the new swine flu vaccines will also receive a seasonal flu vaccine around the same time the scope of this website has been extended to include reporting for all flu vaccines (ie, both seasonal and swine flu).

The most commonly reported suspected ADRs with oseltamivir▼ and zanamivir▼ are consistent with the signs and symptoms of recognised side effects, many of which can also be caused by flu-like illness. The balance of risks and benefits for both oseltamivir and zanamivir within their licensed indications remain positive. However, both drugs are ‘black triangle’ (▼), indicating that all suspected ADRs should be reported, even if they are already recognised. Reporting suspected ADRs enables the MHRA and CHM to have a better picture of the side effect profile of these drugs

Statin patient information leaflets
Statins are generally well tolerated by most people who use them. However, a review of statin safety from 2008 also identified the need for updates to the product information for all statins. Patients should be made aware that treatment with any statin may be associated with depression, sleep disturbances, memory loss and sexual dysfunction. Statins may very rarely be associated with interstitial lung disease. Patients should seek help from their doctor if they develop presenting features of interstitial lung disease such as dyspnoea, non-productive cough, and deterioration in general health (eg, fatigue, weight loss, and fever). Summaries of Product Characteristics (SPCs) and Patient Information Leaflets are being amended to include the potential for these reactions.

Mixing medicines by medical and non-medical prescribers
In palliative care, it is usual to mix two or more medicines in a syringe driver before administration. Strictly speaking, this creates an unlicensed medicine, which raises legal difficulties particularly for non-medical prescribers. In 2008, the MHRA realised that the legal position could potentially obstruct the provision of effective pain relief and symptom control to patients receiving palliative care. As a holding measure, it issued a statement that enforcement action would not be taken for breaches of medicines legislation by independent prescribers and nurses in palliative care who were engaged in mixing medicines, unless it would be in the public interest to do so. It subsequently became clear that mixing of medicines like this was not restricted to palliative care. The MHRA is pressing ahead with necessary legislative amendments. These include allowing non-medical prescribers to be able to mix medicines and direct others to mix, and allowing nurse and pharmacist independent prescribers to prescribe unlicensed medicines for their patients. The National Prescribing Centre (NPC) will be producing a short good-practice guide to support practice in the mixing of medicines post-legislation.

Bisphosphonates and osteonecrosis of the jaw (ONJ)
The risk of ONJ is greater for patients receiving intravenous bisphosphonates for cancer than for patients receiving oral bisphosphonates for osteoporosis or Paget’s disease. All patients with cancer should have a dental check-up before bisphosphonate treatment. During treatment, patients should be encouraged to maintain good oral hygiene; receive routine dental check-ups; and report any oral symptoms such as dental mobility, pain, or swelling.

Colchicine toxicity
Colchicine has a narrow therapeutic window and is extremely toxic in overdose. Patients at particular risk of toxicity are those with renal or hepatic impairment, gastrointestinal or cardiac disease, and patients at extremes of age. The symptoms of overdose are often delayed and all patients, even in the absence of early symptoms, should be referred for immediate medical assessment.

Vigabatrin for infantile spasms: risk of movement disorders and MRI abnormalities
Movement disorders have been reported in patients treated with vigabatrin for infantile spasms. If new movement disorders occur during treatment with vigabatrin, consideration should be given to dose reduction or a gradual discontinuation of treatment in consultation with specialist advice. Cases of abnormal brain MRI findings have also been reported, in particular in young infants treated for infantile spasms with high doses (≥125 mg/kg/day) of vigabatrin. The clinical significance of these findings is currently unknown.

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