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7 Cards in this Set
- Front
- Back
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Indication for L-dopa (levodopa) and Carbidopa (Sinemet)
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L-dopa is NOT a first line therapy for PD, but is given later in the course. Also given for elevation GH release and hyperprolactinemia
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drug action of L-dopa (levodopa) and carbidopa (sinemet)
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L-dopa is a precursor; carbidopa is a peripheral degredation inhibitor which does not cross BBB
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PK of L-dopa and Carbidopa
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oral bioavailablity is only 20-30%. Degredation in stomach and bowel is increased, absorption DECREASED by food (compete for transport across BBB w/Amino Acids)
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adverse events of L-dopa and carbidopa
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Dyskinesias (occur in 80% of the patients within 2-4 mo) which are head bobbing, rocking movements, faciolingual tics, gramacing; "organic brain syndrome"=confusion and delirium; hallucinations, paranoia, mania, persistent nausea and vomiting in 15%.
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Fluctuation of response to L-dopa and carbidopa
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SEVERE: "End-dose akinesia" where they are moving and then all of a sudden they "lock up" and are 'frozen.' Occurs in 30-40% of patients w/in first year. WATCH: in 5-8 years there is "burnout" of DA neurons and drug doesn't work anymore.
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Drug interactions with L-dopa and Carbidopa
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can cause HTN crisis when taken with MAOI- A (depression ones) such as phenelezine (but not with MAOI- B's like selegiline)
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When should you take L-dopa
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must be given two or three hours before a meal, competes with AA transporters to get into brain; may want to use w/DBS to decrease dosage and reduce side-effects
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