The Drug Safety Update is an NHS Evidence accredited provider
14 June 2010
- advice on the risk of medication errors and inappropriate use of rivastigmine transdermal patches for Alzheimer’s dementia
- advice not to use quinine routinely for nocturnal leg cramps
- a ‘Stop press’ article on hypersensitivity and infusion reactions with bevacizumab▼.
Drug Safety Update is an essential read for everyone whose professional practice involves medicines. It is published every month in electronic format only.
Drug safety advice in this edition:
Use of rivastigmine (Exelon) transdermal patch for Alzheimer’s dementia
Medication errors and inappropriate use of rivastigmine transdermal patch have been reported, some of which resulted in overdose and required hospital admission. The most frequently reported causes were lack of patch removal and application of more than one patch at the same time. Symptoms of rivastigmine overdose include nausea, vomiting, diarrhoea, hypertension, and hallucinations. Bradycardia and/or syncope, associated with malaise or falls, may also occur.
It is important that health professionals instruct patients and caregivers on the proper use of the transdermal patch, particularly that:
- only one patch should be applied per day to healthy skin on the upper or lower back, upper arm, or chest
- the patch should be replaced by a new one after 24 hours, and the previous day’s patch must be removed before application of a new patch to a different skin location
- application to the same skin location within 14 days should be avoided to minimise skin irritation
- the patch should not be cut into pieces.
Rivastigmine should only be started if a caregiver is able to regularly give and monitor treatment. If an overdose is suspected, all rivastigmine patches should be removed immediately and no further patch should be applied for the next 24 hours.
Use of quinine for nocturnal leg cramps
Quinine should not be a routine treatment for nocturnal leg cramps, and should only be used when cramps regularly disrupt sleep. Quinine should only be considered:
- when cramps are very painful or frequent
- when other treatable causes of cramp have been ruled out
- when non-pharmacological measures (e.g. passive stretching exercises) have been ineffective
After an initial trial of four weeks, treatment should be stopped if there is no benefit. Quinine is generally well tolerated at the doses used for leg cramps. However, adverse events may include tinnitus, impaired hearing, headache, nausea, disturbed vision, confusion, flushing, and abdominal pain — treatment should be stopped if these occur. Thrombocytopenia is also a rare but potentially life-threatening adverse reaction associated with quinine.
Hypersensitivity and infusion reactions with bevacizumab (Avastin)
Health professionals should be aware that infusion reactions and hypersensitivity reactions have been reported commonly (>1/100–<1/10) during treatment with Avastin. Symptoms reported have included dyspnoea, flushing, rash, hypotension or hypertension, oxygen desaturation, chest pain, rigors, and nausea or vomiting. These reactions normally resolve quickly if the infusion is stopped immediately. More information is available here.
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