Epilepsy is a common disorder affecting the brain, characterised by seizures. There are many different causes and types of epilepsy and diagnosis should involve a specialist medical practitioner, or specialist paediatrician in the case of children. The prevalence of epilepsy in the UK is estimated to be between five and 10 cases per 1,000 of the population and around two thirds of patients have their epilepsy well controlled by antiepileptic drugs.
Counselling points for commonly used antiepileptics
If a patient is prescribed carbamazepine, pharmacist should check whether it is prescribed by brand. If not, a note should be made on the PMR system to supply the same brand because there have been some reports of differences in bioavailability between different preparations. Pharmacists can take the opportunity to remind patients of early signs of toxicity and symptoms that could indicate potential blood, skin or liver disorders. These include fever, sore throat, rash, mouth ulcers or bruising. If a patient develops these symptoms they should be advised to consult their GP immediately.
Patients taking lamotrigine should be reminded of the signs and symptoms associated with blood disorders that could be suggestive of bone-marrow failure, such as anaemia, bruising and infection, with the advice to see their GP if any of these symptoms develop.
If sodium valproate is prescribed, pharmacists can check that appropriate liver function tests have been carried out. Sodium valproate requires liver function tests before therapy and during the first six months of treatment. Remind patients of adverse effects; in this case, the drug can cause blood and hepatic disorders and pancreatitis – signs and symptoms include bruising, nausea and vomiting and abdominal pain.
Women of childbearing age
Many antiepileptic drugs are teratogenic and could disturb the development of an embryo or foetus, so it may be appropriate to discuss family planning options.
In addition, many antiepileptic drugs are enzyme inducers that considerably decrease the effectiveness of oral contraceptives. Some oral contraceptives can still be used off licence after discussion with the prescriber. Patients may have concerns about their method of contraception and pharmacists can discuss the benefits of alternative methods, such as parenteral progesterone-only contraceptives and intra-uterine devices.
If a woman on antiepileptic drugs wishes to start a family she should discuss this with her specialist beforehand and pharmacists could offer support with any changes to medication. Pregnant women should be advised to register with the UK Epilepsy and Pregnancy register; they can also be encouraged to breastfeed if they are taking antiepileptic monotherapy.
Many antiepileptic medicines are modified-release preparations and it is important to check that they are being taken at a similar time each day and not crushed or chewed.
If a patient is having difficulty swallowing a preparation, many of the antiepileptic drugs are available as liquid formulations, chewable tablets or as granules that can be mixed with food. Ideally a patient would be adhering to their prescribed medication and be living seizure-free. Pharmacists could include questions in the MUR around whether a patient is still experiencing seizures and feed this back to the GP if symptoms seem to be worsening. This information supports local practices in gathering data for the quality outcomes framework.
Healthy living advice
Patients taking antiepileptic medications may benefit from advice around stopping smoking, alcohol, diet and exercise in the same way as any other patient.
Heavy drinking can cause seizures, however, small amounts of alcohol have not been shown to increase a patient’s risk of having seizures. Care should be taken because alcohol probably increases the central nervous system side effects of carbamazepine and can increase the sedative effects of other antiepileptics.
Discuss with the patient whether certain activities trigger a seizure and how they can try to avoid them. Nicotine has not been shown to interact with antiepileptic drugs but support and advice can be given to those who wish to stop smoking. Care should be taken with complementary therapies in those on antiepileptics; Chinese herbal medicines, St John’s wort and gingko biloba should all be avoided.
Victoria Tavares is a lecturer in pharmacy practice at Manchester Pharmacy School
Joint Formulary Committee. British National Formulary
Baxter K (ed). Stockley’s Drug Interactions