3.2 Anticonvulsants And Ep

Question 1

Medicines that reduce sei thresholds?

Answer 1

Antibiotics (Penicillins, Cephalosporins, Quinolones)
Antidepressants (Bupropion, TCAs, SSRIs, MAOIs)
Antipsychotics (Clozapine, Chlorpromazine, Haloperidol, Olanzapine, Risperidone, Pimozide)
Bronchodilators (Aminophylline, Theophylline)
Antihistamines (Diphenhydramine, Promethazine)

Question 2

Specific meds that reduce sei threshold?

Answer 2

Baclofen
Ciclosporin
Dexamfetamine
Lithium!
Methylphenidate
Tacrolimus
Tramadol!
Sumatriptan
Erythromycin
Metronidazole
Amitriptyline
Isoniazid

Question 3

Phenytoin indications?

Answer 3

Tonic clonic seis
Focal sei - when other AEDs ineffective
Status epilepticus

Question 4

Phenytoin conversions?

Answer 4

Phenytoin sodium is not equivalent to phenytoin base
100mg sodium = 92mg base

Question 5

Phenytoin cautions?

Answer 5

Enteral feeding: interrupt feed 2 hours before and after dose
IV use: hypotension, respiratory depression, hf, formulation is irritant thus given through central line using filter
Highly protein bound: caution in pts with low albumin

Question 6

Phenytoin side effects?

Answer 6

Acne
Hirsutism
Coarsening facial hair
Gingival hypertrophy: maintain good oral hygeine

Question 7

Phenytoin overdose signs?

Answer 7

Nystagmus: repetitive uncontrolled eye movements
Diplopia: double vision
Slurred speech
Confusion
Hyperglycaemia
Ataxia: no muscle control in arms and legs

Question 8

Phenytoin monitoring?

Answer 8

Han Chinese and Thai pts increased risk of SJS
IV administration: HR and BP
Therapeutic range: 10-20mg/L
Liver function test and FBC

Question 9

Phenytoin counselling?

Answer 9

Recognise blood disorders and skin disorders
Maintain good oral hygiene
Recognise signs of toxicity and seek medical advice

Question 10

Phenytoin interactions?

Answer 10

Enzyme inducer: lots of interactions
Pharmacokinetics: small increase in dose can result in large increase in plasma drug concs