Epilepsy - 2

Question 1

Which AEDs can cause blood dyscrasias?

Answer 1

C Vet PLz

carbamazepine
valproate
ethosuximide
topiramate
phenytoin
lamotrigine
zonisamide

report signs of infection, bruising or bleeding

Question 2

What is the therapeutic range for phenytoin?

Answer 2

10-20mg/L (same as theophylline) (or 40-80micromol/L

Question 3

How does hepatic impairment affect phenytoin?

Answer 3

increased risk of accumulation and toxicity due to decreased protein binding in hepatic impairment, hypoalbuminaemia, or hyperbilirubinaemia

is high protein bound drug

Question 4

What are the symptoms of phenytoin toxicity?

Answer 4

SNATCHED

slurred speech
nystagmus
ataxia
confusion
hyperglycaemia
diplopia, blurred vision

Question 5

What are the side effects of phenytoin?

Answer 5

PHENYTOIN

P45 inducer
hirsutism
enlarged gums (gingival hypertrophy)
nystagmus
teratogenicity
osteopenia - induces vitamin D metabolism
interferes with folic acid: anti-folate, risk of blood dyscrasia
neuropathy

changes in appearance: acne, hirusutism, gingival hypertrophy

Question 6

How must phenytoin be given if being enterally fed?

Answer 6

interrupt feeding for 2 hours before and after dose

more frequent monitoring may be necessary

Question 7

What supplementation is needed in phenytoin use?

Answer 7

induces vitamin D metabolism

vitamin D supplementation in patients who
- are immobilised for long periods
- who have inadequate sun exposure or dietary intake of calcium.

Question 8

How does the HLA-B*1502 allele affect patients on phenytoin?

Answer 8

individuals of Han Chinese or Thai origin, may be associated with an increased risk of Stevens-Johnson syndrome.

Question 9

What are red flags for phenytoin?

Answer 9

blood dyscrasia: report signs of infection, bruising, bleeding, withdraw if leucopenia

skin disorder: report rash - SJS in Han Chinese or Thai patient

hepatotoxicity: dark urine, jaundice, n+v - discontinue

Question 10

What is the MHRA warning for phenytoin?

Answer 10

risk of death and severe harm from error with injectable phenytoin

IV side effects if given too quickly: respiratory depression, hypotension heart failure

Question 11

What monitoring is needed for phenytoin?

Answer 11

blood counts
vitamin D
TDM: 10-20mg/LW

Question 12

What are the main drug interactions for phenytoin?

Answer 12

increased anti-folate effect: methotrexate, trimethoprim

anticonvulsant effect antagonised: SSRIs, mefloquine, tramadol, quinolones, antipsychotics

Question 13

What is the therapeutic range for carbamazepine?

Answer 13

4-12mg/L

Question 14

What are the symptoms of toxicity for carbamazepine?

Answer 14

I HANDBAG

incoordination
hyponatraemia
ataxia
nystagmus
drowsiness
blurred vision and diplopia
arrhythmias
gastrointestinal disturbances

Question 15

What are the red flags for carbamazepine?

Answer 15

blood dyscrasia: leucopenia, thrombocytopenia - report signs of infection, bruising or bleeding

skin disorder: rash, SJS, TEN - report rash

hepatotoxicity: dark urine jaundice

discontinue for all

Question 16

What side effects are dose related for carbamazepine?

Answer 16

dizziness, drowsiness, ataxia, nausea, blurred vision

more common at the start and in elderly: MR reduced side effects

Question 17

Which AEDs are associated with increased risk of major congenital malformations, neurodevelopment disorders?

Answer 17

carbamazepine, phenobarbital, phenytoin, and topiramate

Question 18

What is the risk associated with the presence of HLA-B1502 allele and HLA-A3101 allele?

Answer 18

HLA-B*1502 allele
- in individuals of Han Chinese or Thai origin, is strongly associated with an increased risk of Stevens-Johnson syndrome
- needs pre sreening

HLA-A*3101 allele
- particularly in individuals of European or Japanese origin, is associated with an increased risk of cutaneous adverse reactions

Question 19

What monitoring is needed for carbamazepine?

Answer 19

TDM: 4-12mg/L
blood counts
hepatic function tests
renal function tests

Question 20

What are the main drug interactions for carbamazepine?

Answer 20

increased risk of hyponatraemia: diuretics, SSRIs, NSAIDs, aldosterone antagonists

increased risk of hepatotoxicity: tetracyclines, methotrexate, isoniazid, statins, sulfasalazine

Question 21

What supplementation is needed in carbamazepine use?

Answer 21

induces vitamin D metabolism

vitamin D supplementation in patients who
- are immobilised for long periods
- who have inadequate sun exposure or dietary intake of calcium.

Question 22

What are the prescription requirements for PPP drugs?

Answer 22

7 day prescription validity
30 day supply
exclude pregnancy before treatment

Question 23

What are the side effects of sodium valproate?

Answer 23

VALPROATE

vomiting/nausea
appetite increased
*liver failure
*pancreatitis
reversible hair loss
oedema
ataxia
teratogenicity, tremore
encephalopathy

hyponatraemia

Question 24

What are the red flags for sodium valproate?

Answer 24

hepatic dysfunction: report signs of liver toxicity

blood dyscrasia: leucopenia, thrombocytopenia - report signs of infection, bruising and bleeding

pancreatitis: report abdominal pain oedema, tachycardia

withdraw all

Question 25

What supplementation is needed in sodium valproate use?

Answer 25

vitamin D supplementation in patients who - are immobilised for long periods - who have inadequate sun exposure or dietary intake of calcium.

Question 26

What monitoring is needed for sodium valproate?

Answer 26

LFTs FBC

Question 27

What are the red flags for lamotrigine?

Answer 27

skin reactions: SJS, TEN - report rash blood disorder: bone marrow failure - report anaemia, bruising, or infection

Question 28

What are the red flags for vigabatrin?

Answer 28

encephalopathic symptoms: sedation, confusion, stupor visual field defects: report any symptoms, persist despite discontinuation (CI in visual field defects)

Question 29

What are the monitoring requirements for vigabatrin?

Answer 29

neurological function: psychosis, depression

Question 30

What are the red flags asoictaed with topiramate?

Answer 30

acute myopia with secondary angle-closure glaucoma - typically occurring within 1 month of starting treatment. raised IOP - withdraw

Question 31

What are the contraceptive requirements for topiramate?

Answer 31

highly effective contraception must be used during and for at least 4 weeks after stopping treatment

Question 32

What is the MHRA warning for gabapentin and pregabalin?

Answer 32

severe respiratory depression - report trouble breathing or shallow breathing - a noticeable change in breathing may be associated with sleepiness. dose adjustment in patients at higher risk of respiratory depression

Question 33

What is the MHRA warning for pregabalin?

Answer 33

increased risk of major congenital malformations - need to use effective contraception during treatment

Question 34

What monitoring is required for ethosuximide?

Answer 34

blood disorder: report bone marrow suppression

Question 35

What monitoring is required for phenobarbital?

Answer 35

TDM: 15-40mg/L - less useful due to tolerance

Question 36

What is the lines of treatment for status epileptics?

Answer 36

if resuscitation facilities are available 1st: IV lorazepam if resuscitation facilities are not available 1st: rectal diazepam or buccal midazolam (unlicensed) repeat dose if not stopped whiting 5-10 minutes 3rd: levetiracetam, phenytoin, sodium valproate

Question 37

How status epilepticus be managed?

Answer 37

positon patient to avoid injury support respiration: can provide oxygen maintain blood pressure correct hypoglycaemia IV thiamine: if alcohol abuse suspected pyridoxine: if suspected to be caused by deficiency