Epilepsy and other seizure disorders Flashcards
(46 cards)
Choosing an antiepileptic drug depends on
several factors, and the seizure type should determine the choice of treatment.
- A single antiepileptic drug should be prescribed wherever possible
- Most antileptics can be given twice daily and the dose should be kept as low as possible to encourage adherence.
- If treatment with one drug fails it should be stopped and another drug should be tried alone. The first drug should slowly be withdrawn only when the new regimen has been established.
- Combination therapy with 2 or more drugs may be necessary, but this increases the risk of interactions and side effects.
MHRA Advice: 3 risk-based categories of antiepileptic drugs: category 1
- Category 1: Phenytoin, Carbamazepine, Phenobarbital + Primidone. Patient should be maintained on a specific manufacturer’s product (specific brand).
Antiepileptic hypersensitivity syndrome
If after a few weeks the patient develops a rash, fever and lymphadenopathy this is indicative of antiepileptic hypersensitivity syndrome –> THE DRUG SHOULD BE STOPPED IMMEDIATELY.
Withdrawal
- Avoid abrupt withdrawal because this can cause severe rebound seizures.
- The dose should be reduced gradually, and in the case of barbiturates withdrawal of the drug may take months.
- Even in patients who have been seizure-free for several years, there is a significant risk of seizure-recurrence on drug withdrawal.
- In patients receiving several anti-epileptic drugs, only one drug should be withdrawn at a time.
Driving
If a driver has a seizure (of any type) they must stop driving immediately and inform the DVLA.
To continue driving, the patient must be seizure-free for atleast 1 year.
Patients who have had a seizure while asleep cannot drive for 1 year from the date of each seizure unless:
- The seizures occur only ever while asleep or
- A pattern of PURELY ASLEEP SEIZURES can be demonstrated over the course of 3 years IF the patient has previously had seizures whilst awake (or awake and asleep).
Pregnancy
- There is an increased risk of TERATOGENICITY associated with using antiepileptic drugs. The risk is highest for Valproate.
- It may be in the best interest of the fetus to withhold antiepileptics during the first trimester.
- Women of child-bearing potential who take anti-epileptic drugs should be given advice about the need for effective contraception to avoid unplanned pregnancy.
- If treatment with antiepileptic drugs must continue throughout pregnancy, then MONOTHERAPY is preferable at the lowest effective dose.
To reduce the risk of neural tube defects
• To reduce the risk of neural tube defects (defects of the brain, spine or spinal cord), folate supplementation is advised before conception and throughout the first trimester.
Breastfeeding
Women taking anti-epileptic monotherapy should be encouraged to breastfeed. All infants should be monitored for sedation, feeding difficulties, adequate weight gain and developmental milestones.
Types of seizures
- Focal = localised to one hemisphere of the brain
- Tonic-clonic = Tonic (body is rigid), Clonic (uncontrolled jerking)
- Myoclonic = shock-like jerks of muscles,
- Absence = spells of STARING.
first-line & 2nd line options for focal seizures
Carbamazepine and Lamotrigine;
2 line: Levetiracetam, oxcarbazepine, sodium valproate (consider treatment with phenytoin as adjunctive is poor control)
first-line & 2nd line treatment for tonic-clonic
Sodium Valproate;
2nd line: Lamotrigine
3rd line: if both contra, carbamazepine, oxcarbazepine
first-line & 2nd line options of absence seizures
Ethosuximide or Sodium Valproate.
2nd line: lamotrigine
Dravet syndrome:
Sodium valproate or topiramate are first line
Lennox-Gastaut syndrome:
Sodium valproate is first line
Atonic and tonic seizures:
Usually seen in childhood, sodium valproate is first line
Carbamazepine advice
It is essential to initiate this drug at a low dose and build it up slowly.
It may exacerbate tonic, atonic, myoclonic and absence seizures so should be avoided if these seizures are present.
Patients should be told how to recognise signs of blood, liver and skin disorders: fever, rash, mouth ulcers, bleeding or bruising. In this case: the drug should be WITHDRAWN IMMEDIATELY.
Gabapentin and Pregabalin
Gabapentin and Pregabalin are used for the treatment of focal seizures. They are not recommended if tonic, atonic, absence or myoclonic seizures are present.
Gabapentin safety information:
the levels of propylene glycol, acesulfame K and saccharin sodium may exceed the recommended WHO daily intake limits if high doses of gabapentin oral solution (ROSEMONT BRAND) are given to adolescents or adults with a low body weight (39-50kg)
- risk of severe resp. depression
Lamotrigine
- Lamotrigine can be used for focal, tonic-clonic, absence and as an adjunctive in atonic or tonic seizures.
- Myoclonic seizures may be exacerbated by Lamotrigine
- Valproate increases plasma-lamotrigine concentration whereas enzyme-inducing epileptics reduce it.
Lamotrigine SE
Skin reactions … Severe skin reactions including SJ syndrome and toxic epidermal necrolysis have developed especially in children, most rashes occur within the first 8 weeks. Consider withdrawal if rash or signs of hypersensitivity syndrome develop. Factors associated with increased risk of serious skin reactions include concomitant use of valproate, initial lamotrigine high dosing and more rapid dose escalation. Look out for signs of bone marrow failure: anaemia, bruising or infection.
Phenytoin
• Phenytoin is licensed for tonic-clonic and focal seizures but may exacerbate absence or myoclonic seizures.
• It has a NARROW THERAPEUTIC WINDOW and small dosage increases may produce LARGE increases in plasma concentration with acute toxic side-effects (Non-linear dose-plasma relationship).
- Similarly, a few missed doses or small change in drug absorption may result in a marked change in plasma-drug concentration. Thus, plasma-drug concentration should be monitored.
Phenytoin SE
- Rash: discontinue, if mild then re-introduce cautiously but discontinue immediately if recurrence
- Bradycardia & hypotension: With IV: reduce rate of administration if bradycardia or hypotension occur
- Overdose: symptoms of phenytoin toxicity include nystagmus, diplopia, slurred speech, ataxia, confusion and hyperglycaemia
- Blood or skin disorders: if fever, rash, mouth ulcers, bruising or bleeding seek medical attention urgent
- change in appearance (coarsening of hair)
- low vitamin D
- hepatotoxicity
- suicidal thoughts
Topiramate SE
This drug can be given alone or as an adjunctive treatment in generalised tonic-clonic or focal seizures.
Side effects: Acute myopia (close objects look clear but distant objects are blurry) with secondary angle-closure glaucoma typically occurring within 1 month of starting treatment. If raised intraocular pressure occurs, seek ophthalmological advice + stop topiramate as rapidly as feasible.
Sodium Valproate cautions
It is the drug of choice for many types of seizures. Take with or just after food unless e/c tablet.
Cautions: Liver dysfunction can occur when taking Valproate usually in the first 6 months, so liver function must be monitored. Raised liver enzymes during Valproate therapy are temporary but liver function must be monitored until return to normal – discontinue if abnormally long prothrombin time
- pancreatitis (abdominal pain, nausea, vomit)
Withdraw if persistent vomiting and abdominal pain, anorexia, jaundice, oedema, malaise, drowsiness or loss of seizure control. Discontinue treatment is symptoms of pancreatitis develop (abdominal pain, nausea or vomiting). Advise patients how to recognise symptoms of blood or liver disorders.
It should not be used in women and girls of child-bearing potential unless alternatives are ineffective/not tolerated due to its high teratogenic potential.
Gives false-positive urine tests for ketones
