Anticonvulsants - Sodium Valproate Flashcards
What is sodium valproate used for?
1) Epilepsy (genaralised siezures)
2) Bipolar disorder
How does sodium valproate work?
- inhibits neuronal sodium channels
- less action potentials fires
- increases y-aminobutyric acid (GABA) in brian which is an inhibitory neurotransmitter so controls neuronal excitability.
What are the side effects of sodium valproate?
1) GI upset (nausea / vomiting)
2) neuro / psych (tremor, ataxia, behaviour change)
3) thrombocytopenia
4) increase in liver enzymes
5) Allergic reactions —> hair loss
6) RARE - liver injury, pancreatitis, bone marrow failure
7) Antiepileptic hypersensitivity syndrome
What is anti-epileptic hypersensitivity syndrome?
triad of
1) fever,
2) skin eruption,
3) internal organ involvement (ie, hepatitis, nephritis, lymphadenopathy)
Why should sodium valproate be avoided in women of child bearing age and 1st trimester of pregnancy?
Sodium Valproate is the antiepileptic drug with the highest risk of fetal abnormalities. e.g neural tube defect, craniofacial, cardiac and limb abnormalities.
When should sodium valproate be avoided?
- women at risk of pregnancy
- hepatic impairment
When is dose reduction of sodium valproate required?
-severe renal impairment
What are drug interactions of sodium valproate?
1) drugs metabolised by P450 enzymes (e.g. warfarin, oestrogen, progestogen) because sodium V increased P450 enzyme activity.
2) Drugs that inhibit cytochrome P450 inhibitors (e.g. macrolides, protease inhibitors)
3) drugs that displace Sodium V from protein binding sites e.g. aspirin.
4) SSRIs, tricyclic anti depressants, anti psychotics, tramadol
What route is sodium valproate administered?
Oral or IV
How is the safety of sodium valproate monitored?
- patient report
- liver function (prothrombin time) before start and in first 6 months of treatment.
