SODIUM VALPROATE

Question 1

Monitoring

Answer 1

Liver function, full blood count, weight, BMI.

Question 2

Warning signs

Answer 2

• Persistent vomiting, abdominal pain, anorexia
• Jaundice, oedema, malaise drowsiness
• Loss of seizure control
• Suicidal ideation or behaviour

Question 3

Action and interactions

Answer 3

Actions Required

• All women of child bearing age must be enrolled in a pregnancy prevention programme. Prescribers should ensure the patient understands the risks associated with valproate use in pregnancy, the need to use highly effective contraception, the need for regular review of treatment and that the woman should rapidly consult her doctor if she is planning a pregnancy or becomes pregnant.
• Treatment in women of child bearing age should not have therapy initiated without a negative pregnancy test. They should also have regular pregnancy tests throughout therapy.
• Women of child bearing potential should use a highly effective method of contraception throughout treatment. A user independent contraceptive method such as an IUD or implant is preferred or two complementary forms of contraception including a barrier method should be used.
• Patients that are immobilised for long periods or have inadequate sun exposure or dietary intake of calcium should take vitamin supplementation.
• Category 2 antiepileptic, brand dispensing based on clinical judgement.
• Abrupt withdrawal should be avoided, the valproate dose should be reduced gradually over at least 4 weeks.

Interactions

• Effects of other psychotropics such as antipsychotics, MAO inhibitors, antidepressants and benzodiazepines potentiated.
• Anticoagulant effect of warfarin increased.

• Metabolism of lamotrigine reduced and its half-life almost doubled, leading to increased lamotrigine toxicity particularly serious skin reactions.

• Erythromycin and cimetidine may increase valproic acid plasma levels by reducing hepatic metabolism.
• Anti-epileptics with enzyme inducing effect decrease valproic acid plasma concentrations.