Parkinson's disease Flashcards
what is the biggest risk factor for PD?
The biggest risk factor for the disease is age, which has major implications for public health as the lifespan of the world’s population increases.
what is bradykinesia?
slowness of movement
what are the other cardinal features of PD?
The cardinal features of the disease are bradykinesia, tremor when at rest (pill-rolling tremor), postural instability and cogwheel rigidity.
what is cogwheel rigidity?
Cogwheel rigidity describes the jerky resistance when limbs are moved.
PD presents as asymmetrically or symmetrically?
The disease presents asymmetrically and patients continue to report a ‘bad side’ as the disease progresses, although pure unilateral disease is rare, and usually raises concerns that some other disease process is occurring if this is the case.
how postural instability affects in PD?
Postural instability is an important milestone in PD, and typically more than half of patients will reach this stage within 10 years of diagnosis. This problem comprises an impairment of righting reflexes, which leads to impaired gait and increased risk of falling.
Features of PD?
Patients typically display a characteristic stooped posture and loss of arm swing when walking, which is often a very helpful early diagnostic sign when seeing patients for the first time.
There is reduced blink frequency and facial expression (hypomimia), which, together with a low-volume (hypophonic), monotonous speech, may lead to significant difficulties in communication. All of this can easily be misdiagnosed as depression.
Writing becomes small (micrographia) and barely legible, with the words falling off the line as the patient continues to write.
which antiemetics can induce- Parkinsonism?
Cinnarizine, metoclopramide, prochlorperazine
which antipsychotics can induce- Parkinsonism?
Dose-dependent effects; clozapine least associated with abnormal movements
which other drugs can induce- Parkinsonism?
Sodium valproate, Non-steriodal antiinflammatory drugs, amiodarone, phenytoin, oral contraceptives
can lithium induce- Parkinsonism?
Lithium causes postural tremor; reports of Parkinsonism occurring with lithium have usually been in the context of prior exposure to neuroleptics
Drug-induced Parkinsonism is more common in which groups?
Drug-induced Parkinsonism is more common in the elderly and in women.
what are the clinical features of Drug-induced Parkinsonism?
The clinical features can be indistinguishable from PD, although the signs in drug-induced Parkinsonism are more likely to be bilateral at onset.
Drug-induced Parkinsonism is reversible or irreversible?
Withdrawal of the offending agent will lead to improvement and resolution of symptoms and signs in approximately 80% of patients within 8 weeks of discontinuation. Drug-induced Parkinsonism may, however, take up to 18 months to fully resolve in some cases. Further, in other patients, the Parkinsonism may improve after stopping the drug, only to then deteriorate. In this situation, the drug may have unmasked previously latent PD.
what is dyskinesia?
Dyskinesias are involuntary, erratic, writhing movements of the face, arms, legs or trunk.
co-careldopa or sinemet is formulated with?
carbidopa plus levodopa is known as co-careldopa (Sinemet)
co-beneldopa or madopar is formulated with?
benserazide plus levodopa is co-beneldopa (Madopar).
what is the drug regimen for immediate release of co-beneldopa?
Immediate-release co-beneldopa is usually commenced in a dosage of 50 mg, typically three times a day.
how levodopa affects the absorption?
The patient may be instructed in the early stage of the illness to take the drug with food to minimise nausea. Paradoxically, in more advanced PD, it may be beneficial to take levodopa 30 minutes or so before food, as dietary protein can critically interfere with the absorption of the drug.
side effects of levodopa?
Nausea, vomiting and orthostatic hypotension are the most commonly encountered side effects.
Later in the illness, and in common with all anti-Parkinsonian drugs, levodopa may cause vivid dreams, nightmares or even precipitate a confusional state, which tends to indicate that the patient is starting to develop a PD dementia.
what are the significant interactions with levodopa?
Levodopa can also enhance the hypotensive effects of antihypertensive agents and may antagonise the action of antipsychotics. The absorption of levodopa may be reduced by concomitant administration of oral iron preparations.
what is the bioavailability of immediate and controlled release levodopa formulations?
Levodopa in CR preparations has a bioavailability of 60– 70%, which is less than the 90– 100% obtained from immediate-release formulations. CR preparations have a response duration of 2– 4 hours, compared with 1– 3 hours for immediate release.
in what situations controlled release levodopa can be used?
simplifying drug regimens, in relieving nocturnal akinesia, and in co-prescribing with immediate-release levodopa during the day to relieve end-of-dose deterioration.
what are the problems associated with controlled release levodopa preparations?
Two commonly encountered problems with CR preparations are, first, changing the patient from all immediate-release to all CR levodopa. This is poorly tolerated, because CR levodopa has a longer latency than immediate-release levodopa to turn the patient ‘on’ (typically 60– 90 vs 30– 50 minutes), and the patient’s perception is that the quality of their ‘on’ period is poorer. Second, CR preparations should not be prescribed more than four times a day, because the levodopa may accumulate, causing unpredictable motor fluctuations and especially leading to dyskinesias later in the day.
