30 Questions
Which enzyme do entacapone and tolcapone inhibit to block the conversion of dopamine?
Catechol-O-methyltransferase
What is the main route of excretion for the metabolites of safinamide?
Renal excretion
Which metabolite of entacapone is found in human plasma as an inactive form?
(Z)-entacapone
What are the most common adverse effects associated with safinamide?
Uncontrolled involuntary movements, nausea, insomnia, falls
Individuals using which of the following medications should not use safinamide?
Monoamine oxidase inhibitors
Which medication is significantly metabolized prior to excretion, with only 0.2% of the parent drug found unchanged in urine?
Entacapone
What is the main metabolic pathway for the parent drug of entacapone?
Glucuronidation by UGT1A9
Which enzyme is a selective and reversible inhibitor in the context of Parkinson's disease treatment?
Catechol-O-methyltransferase
What percentage of the urinary metabolites do the resulting glucuronides from the parent drug and the alkene isomer represent?
70% and 25%
Which neurological condition is tolcapone indicated for as an adjunct therapy?
Parkinson's disease
What effect does the nitro group have on the metabolism of the catechol of entacapone?
Blocks catechol-O-methyltransferase-mediated methylation
In the cocrystal structure of tolcapone, what interaction does the catechol of tolcapone form?
Interaction with Mg2+ ion, hydrogen bond to Asn170, and ionic-dipole interaction with Glu199
Which enzyme is inhibited by safinamide?
Monoamine oxidase
What is the primary route of elimination for the metabolites of entacapone?
Urine
Which compound may form directly by autooxidation of the parent drug carbidopa?
3,4-dihydroxyphenylacetone
What is the main mechanism of action for tolcapone in the treatment of Parkinson's disease?
COMT inhibitor
What are the most common adverse events in advanced Parkinson's disease patients treated with carbidopa?
Nausea and headache
Iron salts can reduce the bioavailability of carbidopa by:
Chelating carbidopa
Why does transfer not occur likely in the case of tolcapone?
Strong electron-donating effect of the nitro group
What is the primary metabolite of tolcapone?
Glucuronide of the more sterically accessible phenol
Which enzyme is responsible for mediating methylation to 3-Omethyl-tolcapone?
Catechol-O-methyltransferase
What percentage of tolcapone is found unchanged in urine?
0.5%
Which enzyme is not involved in the metabolism of tolcapone?
COMT
What is a minor metabolite formed from tolcapone?
An aniline that is subsequently acetylated
What are the most common adverse effects associated with tolcapone?
Nausea, anorexia, sleep disorder, vomiting
Which enzyme is primarily inhibited by tolcapone?
Catechol-O-methyltransferase
Which of the following is a dopamine receptor agonist used in the treatment of Parkinson's disease?
Pramipexole
What is the mechanism of action of apomorphine in the treatment of Parkinson's disease?
Stimulation of postsynaptic dopamine D2-type receptors
Which class of alkaloids is apomorphine related to?
Aporphine alkaloids
In the treatment of advanced Parkinson's disease, what is safinamide indicated for?
Hypomobility or 'off' episodes
Test your knowledge on the metabolism of entacapone, a drug primarily metabolized via glucuronidation by UGT1A9 to generate regioisomeric metabolites. Learn about the common adverse effects and metabolic pathways involved.
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