Question

Given below are two statements:
Statement I: Levodapa is metabolized peripherally but capable of crossing Blood Brain Barrier, thus a best drug in treating Parkinsonism.
Statement II: Carbidopa crosses. Blood Brain Barrier, thus a best combination for protecting levodapa inCNS. 
In light of the above statements, choose the correct answer from the options given below:

• A. Both Statement I and Statement II are true
• B. Both Statement I and Statement II are false
• C. Statement I is true but Statement II is false
• D. Statement I is false but Statement II is true

Answer 1

The Correct Option is B

Let's analyze each statement to determine their correctness:

1. Statement I: "Levodopa is metabolized peripherally but capable of crossing Blood Brain Barrier, thus a best drug in treating Parkinsonism."
   • Explanation: Levodopa (L-DOPA) is the primary treatment for Parkinson's disease because it can cross the blood-brain barrier (BBB) where it is converted to dopamine, which is deficient in Parkinson's disease patients.
   • However, a significant amount of levodopa is metabolized peripherally (before reaching the brain), which reduces its effectiveness as a treatment. To mitigate this, it is often combined with a peripheral decarboxylase inhibitor like carbidopa, which does not cross the BBB. Therefore, without the combination, it is not considered the "best" drug on its own due to peripheral metabolism reducing its central effects.
2. Statement II: "Carbidopa crosses Blood Brain Barrier, thus a best combination for protecting levodopa in CNS."
   • Explanation: Carbidopa does not cross the blood-brain barrier. Its role is to inhibit the peripheral metabolism of levodopa, thus increasing the amount of levodopa available to cross into the brain.
   • By not crossing the BBB, Carbidopa ensures that more levodopa is available for central conversion to dopamine, which is crucial for its therapeutic effects in Parkinsonism. Therefore, this statement is false as it misrepresents Carbidopa's mechanism of action.

The examination of both statements indicates that:

• Statement I is misleading because it doesn't account for the role of peripheral metabolism without mentioning the adjunct use of a decarboxylase inhibitor.
• Statement II is factually incorrect regarding the ability of carbidopa to cross the blood-brain barrier.

Conclusion: Both Statement I and Statement II are false. Hence, the correct answer is: Both Statement I and Statement II are false.