Question

Which one of the following statements is TRUE regarding drugs used in parkinsonism?

• A. Amantadine causes ankle oedema
• B. Levodopa is particularly effective in reducing tremor
• C. Amantadine is more effective than levodopa
• D. Antimuscarinics are effective in drug-induced parkinsonism

Hint:

Amantadine's classic side effects are ankle oedema and livedo reticularis. Levodopa helps tremor least of the cardinal signs, and only central antimuscarinics work in drug-induced parkinsonism.

Answer 1

The Correct Option is A

Step 1: Recall the main drugs used in parkinsonism.
The major drug classes are levodopa (with carbidopa), dopamine agonists, amantadine, and antimuscarinic (anticholinergic) agents. Each acts differently and has its own side effect profile.

Step 2: Check option 1, amantadine and ankle oedema.
Amantadine is known to cause peripheral oedema, most often around the ankles, along with livedo reticularis, a mottled purplish skin discoloration on the legs. This is a well documented adverse effect. This statement IS true.

Step 3: Check option 2, levodopa and tremor.
Levodopa works best against bradykinesia (slowness of movement) and rigidity. Its effect on tremor is present but usually the weakest and slowest of the three cardinal signs to respond, tremor often improving last, if at all. So calling levodopa "particularly effective" for tremor is incorrect.

Step 4: Check option 3, amantadine versus levodopa.
Amantadine has a faster onset of action than levodopa but is a much weaker drug overall, used mainly for mild symptoms or as an add-on. Levodopa remains the most effective drug for parkinsonism. So amantadine being "more effective" is incorrect.

Step 5: Check option 4, antimuscarinics in drug-induced parkinsonism.
Antimuscarinics do help in drug-induced parkinsonism, but only the centrally acting ones (drugs that cross into the brain, such as trihexyphenidyl), because the problem there is an imbalance between dopamine and acetylcholine in the brain, not in peripheral tissue. The statement as worded, calling all antimuscarinics effective, is too broad and therefore not strictly correct.

Step 6: Final answer.
Only the statement about amantadine causing ankle oedema is fully correct as written.
\[ \boxed{\text{Amantadine causes ankle oedema}} \]