The Medicines and Healthcare products Regulatory Agency (MHRA) has published Drug Safety Update for November 2013 (PDF).
This issue contains drug safety advice reminding clinicians of the new advice on switching between different manufacturers’ products of antiepileptic drugs and about the strengthened warnings on neuropsychiatric side effects associated with mefloquine.
Additionally, this update advises that there is new evidence on neurodevelopmental delay in children following maternal use of sodium valproate. A review is in progress but in the meantime clinicians are reminded that sodium valproate must not be used during pregnancy unless there is no effective alternative.
Finally, clinicians are warned that there have been cases of intraoperative floppy iris syndrome (IFIS) during cataract surgery have been reported in patients taking the atypical antipsychotics risperidone or paliperidone. Complications can arise during or after surgery and it is recommended that use of these drugs is notified on referrals for cataract surgery.
Action: Clinicians will find this publication to be a useful review of current issues in drug safety.
The Medicines and Healthcare products Regulatory Agency (MHRA) has written to healthcare professionals to provide information about switching between different manufacturers’ products of antiepileptic drugs (AEDs). This includes switching between branded products and generic products, and between different generic products of a particular drug.
Following a review of the available evidence and consideration of the bioavailability and pharmacokinetic characteristics of the different drugs it has been suggested that they could be classified into three categories:
- Category 1 (Phenytoin, carbamazepine, phenobarbital, primidone). For these drugs, doctors are advised to ensure that their patient is maintained on a specific manufacturer’s product.
- Category 2 (Valproate, lamotrigine, perampanel, retigabine, rufinamide, clobazam, clonazepam, oxcarbazepine, eslicarbazepine, zonisamide, topiramate). For these drugs the need for continued supply of a particular manufacturer’s product should be based on clinical judgement and consultation with patient and/or carer taking into account factors such as seizure frequency and treatment history.
- Category 3 (Levetiracetam, lacosamide, tiagabine, gabapentin, pregabalin, ethosuximide, vigabatrin). For these drugs it is usually unnecessary to ensure that patients are maintained on a specific manufacturer’s product unless there are specific concerns such as patient anxiety, and risk of confusion or dosing errors.
A patient information leaflet has been prepared and provides a summary of what these changes means.
Action: Clinicians will already be aware of the need to prescribe by brand for the specified medicines. This document is helpful in indicating where more flexible prescribing can be considered.
The Scottish Medicines Consortium (SMC) has issued its monthly advice on newly licensed medicines.
Atomoxetine (Strattera®) has been accepted for use in the treatment of attention-deficit/hyperactivity disorder (ADHD) in adults as part of a comprehensive treatment programme. They recommend that the presence of symptoms that were pre-existing in childhood should be confirmed.
Ondansetron orodispersible films (Setofilm®) have been accepted for restricted use in nausea and vomiting associated with emetogenic chemotherapy and post-operative nausea and vomiting (PONV). The review notes that generic preparations of ondansetron are available at a lower cost than the proprietary products.
Sodium phenylbutyrate granules (Pheburane®) have been accepted for use as an adjunctive therapy in the chronic management of urea cycle disorders. It is noted that this product provides an alternative to sodium phenylbutyrate tablets at no additional cost but is more expensive than an existing brand of sodium phenylbutyrate granules.
Action: Clinicians should be aware of the recommendations of the SMC. Routine use of rejected and restricted medicines should be avoided.
The manufacturer of mefloquine (Larium®) has written to healthcare professionals with an update on the risk of neuropsychiatric adverse reactions associated with use of this medication.
Mefloquine has been known to potentially cause neuropsychiatric adverse reactions such as abnormal dreams, insomnia, anxiety and depression for some time. Less frequently hallucinations, psychosis, suicide and suicidal thoughts have been reported. Due to the long half-life of mefloquine, such reactions may persist for several months after discontinuation of treatment.
This letter emphasises the importance of promptly stopping treatment in any patient with signs of neuropsychiatric reactions. It is also recommended that patients are advised about the type of symptoms they might experience that are associated with neuropsychiatric reactions and to stop taking the medication immediately and seek medical advice should they arise. To aid this, the letter includes some Patient Alert Cards and a contraindication check list to use before prescribing.
Action: Clinicians should already be aware of the neuropsychiatric reactions associated with mefloquine use. The prescribing aids included with this letter may prove useful in ensuring safer use of mefloquine.
MTRAC issued two new Commissioning Support reviews in October 2013. The reviews cover perampanel and zonisamide.
The perampanel (Fycompa®) summary advises that this drug is not suitable for prescribing in primary care for adjunctive treatment of partial seizures in epilepsy. It is recommended that prescribing should occur in a tertiary care setting and notes that patients are likely to receive continued specialist supervision.
The zonisamide (Zonegran®) summary advises that this drug is suitable for restricted prescribing under defined conditions as monotherapy for partial seizures in epilepsy. It is recommended that the treatment is initiated and stabilised by a specialist after which maintenance therapy can be issued in primary care. It is expected that patients would continue to receive follow-up in secondary care.
Action: Clinicians should be aware of these reviews and use the recommendations to guide appropriate use of these medicines in current practice.