Author Question: A patient with Parkinson's disease is taking levodopa/carbidopa (Sinemet) and reports occasional ... (Read 142 times)

stock · **on:** Jul 23, 2018

A patient with Parkinson's disease is taking levodopa/carbidopa (Sinemet) and reports occasional periods of loss of drug effect lasting from minutes to several hours.

The nurse questions the patient further and discovers that these episodes occur at different times related to the medication administration. The nurse will contact the provider to discuss:
a. administering a catechol-O-methyltransferase (COMT) inhibitor, such as entacapone.
b. adding the DA-releasing agent amantadine to the regimen.
c. giving a direct-acting dopamine agonist.
d. shortening the dosing interval of levodopa/carbidopa.

Question 2

A group of nursing students asks a nurse to explain the blood-brain barrier. The nurse would be correct to say that the blood-brain barrier:

a. prevents some potentially toxic substances from crossing into the central nervous system.
b. causes infants to be less sensitive to CNS drugs and thus require larger doses.
c. allows only ionized or protein-bound drugs to cross into the central nervous system.
d. prevents lipid-soluble drugs from entering the central nervous system.

raenoj · **Reply #1 on:** Jul 23, 2018

Answer to Question 1

ANS: A
This patient is describing abrupt loss of effect, or the off phenomenon, which is treated with entacapone or another COMT inhibitor. Amantadine is used to treat dyskinesias. A direct-acting dopamine agonist is useful for gradual loss of effect, which occurs at the end of the dosing interval as the dose is wearing off. Shortening the dosing interval does not help with abrupt loss of effect.

Answer to Question 2

ANS: A
The blood-brain barrier can prevent some drugs and some toxic substances from entering the CNS. The blood-brain barrier in infants is not fully developed, so infants are more sensitive to CNS drugs and often require lower doses. The blood-brain barrier prevents highly ionized and protein-bound drugs from crossing into the CNS and allows lipid-soluble drugs and those that can cross via specific transport systems to enter.