A nurse noticed that Molly was having a seizure.
2(a) (5 minutes)
(i) What drug treatment would be appropriate to manage Molly’s seizure?
(ii) What drug treatment would be appropriate should she require ongoing prophylaxis for seizures?
2(b) Outline the mechanisms of action and the adverse side effects of the drugs you identified in
(i) and (ii) above. (5 minutes)
2(a) Treatment should consider cause of seizure
(e.g. manitol if it is ICP causing pressure)
- Phenytoin is good for prevention of seizure post neurosurgery
- - It is a barbiturate derivative and is still widely used, except for absence seizures.
- Pharmacokinetics: narrow range of plasma concentrations to cause adverse side effects
- - hence therapeutic drug monitoring (TDM) is essential
- Mechanism/Target: blocks voltage-gated sodium channels by selectively binding to the channel in the inactive state and slowing its rate of recovery.
- - prolongs effective refractory period and suppresses ventricular pacemaker automatically, and shortens action potential in the heart
- Adverse effects: Decreased bone mineral density
- - suicidal ideations
- - Can be associated with fetal abnormalities
- Carbamazepine (Tegritol TM ) also Na+ channel blocker (similar to phenytoin), especially good against complex partial seizures
- - Side effects - nausea, headache, rash, dizziness, double-vision
- - Potent enzyme inducer, difficult to titrate. Interacts with numerous other common drugs.
- - May lead to SIADH as it increases release of ADH. Causes reduction in blood cells and platelets. Induces CYP450 so multiple drug interactions including birth control pills. Teratogen.
shows zero-order (saturation) kinetics; clearance is independent of plasma conc, duration of drug action dependent on dose, relationship between dose and steady-state conc steep and unpredictable. plus everyone responds differently to this drug!