Neurological drugs Flashcards
2 examples of L-dopa/peripheral decarboxylase inhibitors?
Co-beneldopa (levodopa and benserazide) and Co-carledopa (levodopa and carbidopa)
How do L-dopa/peripheral decarboxylase inhibitors work?
Crosses BBB and is converted by dopa decarboxylase to replace deficient dopamine in the basal ganglia. The non-L-dopa component of the drug reduces peripheral side effects
L-dopa/peripheral decarboxylase inhibitors are used in Parkinson’s disease, in what eye condition should they not be given?
Closed-angle glaucoma
Why can’t dopamine itself be used as a drug in Parkinsonism disorders
Doesn’t cross BBB
How should drugs used to treat Parkinson’s be discontinued?
Gradually
5 examples of anti-convulsants, each with different mechanism of action*?
Phenytoin, carbamazepine, sodium valproate, lamotrigine, levetiracetam
How does phenytoin work?
Blocks voltage gated Na+ channels preventing spread of epileptic discharges
Indications for phenytoin use?
Status epilepticus, tonic-clonic seizures, focal seizures
What side effects effecting the face can result from phenytoin use?
Facial coarsening, gingival hypertrophy and tenderness, rash, acne, hirsutism
Why should phenytoin be withdrawn gradually?
Abrupt withdrawal can precipitate status epilepticus
How does carbamazepine work?
Increases GABA mediated inhibitory CNS transimission, reduces electrical excitability of cell membranes by blocking Na+ channels
Indications for carbamazepine?
Tonic-clonica and partial seizures, trigeminal neuralgia, bipolar prophylaxis, adjunct in acute alcohol withdrawal, diabetic neuropathy
Contraindications to carbamazepine?
AV node conduction abnormalities, history of bone marrow depression, acute porphyria
How does sodium valproate work?
Increases GABA content of the brain by inhibiting GABA transaminase, preventing GABA reuptake. Also decreases conc. of aspartate (an excitatory neurotransmitter).
Indications for sodium valproate?
All forms of epilepsy, migraine prophylaxis, mania
What is the result of giving 2 or more anticonvulsants?
Increased anticonvulsant effects and sedation
How does lamotrigine work?
Blocks voltage gated Na+ channels, inhibits repetitive firing of neurones and inhibits glutamte release, preventing epileptic seizures
Indications for lamotrigine?
Focal and tonic-clonic seizures, Lennox-Gastout syndrome seizures, absence seizures in kids, prevention of depressive episodes in Bipolar Affective Disorder
When using lamotrigine, why is it important for patients to spot signs of skin disorders?
Could precede Stevens-Johnsons or toxic epidermal necrosis
How does levetiracetam work?
Partially inhibits Ca++ channels, partially reverses reductions in GABA currents
Indications for levetiracetam?
Focal seizures, myoclonic seizures
What is the interaction of levetiracetam and methotrexate?
Reduces methotrexate clearance so need to monitor levels
