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

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8th September 2009

The MHRA and CHM have published the August edition of Drug Safety Update. This issue gives drug safety advice on oseltamivir and zanamivirfor pandemic swine influenza, and on herbal products.

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

Oseltamivirand zanamivir: safety information
As use of oseltamivir and zanamivir for the management of the swine influenza A/H1N1 pandemic will increase in the coming weeks and months, this DSU article outlines some of the key facts on their safe use. Updates on the latest information are available from the MHRA website.

There is substantial experience of use of oseltamivir and zanamivir and both have favourable risk-benefit profiles. Oseltamivir is given orally and zanamivir is given by inhalation. The National Pandemic Flu Service is directing anyone with a kidney disorder or who may be pregnant to their healthcare professional; zanamivir has been procured for these individuals. Health professionals should follow Health Protection Agency advice, but it is important to weigh the likely benefits of treatment against possible harms, including side effects.

The most common side effects of oseltamivir are nausea, vomiting, diarrhoea, abdominal pain, and headache. These may usually occur after the first dose and will usually stop as treatment continues. The frequency of these effects is reduced if the drug is taken with food. More-serious side effects are very rare. Recognised side effects of zanamivir are very rare, but may include allergic-type reactions such as swelling of the face, mouth, or throat; skin rash; or hives. Acute bronchospasm or serious decline in respiratory function (or both) have been seen in patients with a history of asthma or chronic obstructive pulmonary disease (COPD), and in those without a history of respiratory disease. The product information for both antiviral medicines lists neuropsychiatric disorders as a possibleside effect. These events were added to the productinformation as a precautionary measure and a causal association is uncertain.

The DSU article also offers information on drug interactions; use in renal impairment and shelf-life for oseltamivir; and the use of zanamivir in patients with asthma or COPD.

As we reported in a previous blog, the MHRA has set up the Swine Flu ADR Portal, a special web-based system for reporting suspected adverse drug reactions to oseltamivir and zanamivir.

Herbal products: safety update
This article points out that the number of reports of adverse reactions that are suspected to be associated with herbal products is very low and encourages everyone to report any case of an adverse reaction suspected to have been caused by a herbal product or products. Increasing the number of good-quality reports increases the chance of detecting potential side effects and assists assessment of the risk.

As well as providing advice about herbal medicines, the MHRA is responsible for monitoring the safety of herbal medicines in the UK. Key areas of concern about herbal medicines include:

  • Poor and variable quality of unlicensed or unregulated products
  • Deliberate adulteration with potentially toxic ingredients such as heavy metals, arsenic, and prescription-only medicines (including products that have been banned because of safety concerns)
  • Lack of detailed product information.

When submitting a report to the Yellow Card Scheme for a herbal product, the same reporting forms and procedures should be used as for medicines. However, because herbal products can differ depending on the formulation or the species involved, and may be associated with different side-effect profiles, some extra details should be provided, particularly as much information as possible about the herbal product suspected to be involved, such as:

  • The brand name (if it has one)
  • The list of ingredients
  • Ideally, a copy of package labelling
  • Details of the manufacturer.

For serious adverse reactions, it is worth considering asking the patient to retain the herbal product in case the MHRA wishes to test the product.

Monitoring the impact of regulatory actions
To ensure it effectively safeguards public health, the MHRA is committed to monitoring the effect of the actions it takes on medicines. An article in this month’s DSU explains the collaborative work and research that the MHRA engages in to help ensure that its decisions have a positive outcome for patients and the public.

Rotigotine▼ patches: lifting of prescribing restrictions
Prescriptions for rotigotine transdermal patches are no longer limited to one month’s supply and they can once again be prescribed in line with the approved indications of idiopathic Parkinson’s disease or restless legs syndrome. Patients should store their patches in the refrigerator, but not in the freezer. There is no need to bring the patch to room temperature before application.

‘First Steps’ infant medicine feeder: recall due to overdose risk
Anyone who has purchased this infant medicine feeder should stop using the product and dispose of it. The medicine feeder has two scales, millilitres (ml) and teaspoons (tsp). Confusion between the scales led to a serious overdose when a six-month-old infant was repeatedly administered 2.5 tsp (about 13ml) of paracetamol instead of 2.5ml.

Other articles
Patient Information Leaflet of the month: Symbicort

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