USMLE Forum Archives - USMLE Step 1 - Pharmacology question #3
Pharmacology question #3
revision - 01-06-09 07:26
A 72-year-old patient presents complaining of shaking in his right hand and trouble starting movements. On physical examination, the patient has a resting tremor of the right hand that decreases with active movement. The man's face is expressionless, and his voice is very soft. Cogwheel rigidity is noted in both arms. He also has a slightly stooped posture, and a slow, shuffling gait.
Which of the following treatments for this disease works by inhibiting the metabolism of dopamine?
A. Benztropine
B. Bromocriptine
C. Levodopa
D. Pergolide
E. Selegiline
revision - 01-06-09 07:26
A 72-year-old patient presents complaining of shaking in his right hand and trouble starting movements. On physical examination, the patient has a resting tremor of the right hand that decreases with active movement. The man's face is expressionless, and his voice is very soft. Cogwheel rigidity is noted in both arms. He also has a slightly stooped posture, and a slow, shuffling gait.
Which of the following treatments for this disease works by inhibiting the metabolism of dopamine?
A. Benztropine
B. Bromocriptine
C. Levodopa
D. Pergolide
E. Selegiline
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#2
Re: Pharmacology question #3
revision - 01-07-09 01:30 Yes the correct answer is E.
This clinical vignette is classic for Parkinson's disease and all the answer choices are drugs used in the treatment of this disorder.
Selegiline (deprenyl) inhibits monoamine oxidase B (MAO-B). This form of MAO preferentially metabolizes dopamine, whereas MAO-A preferentially metabolizes norepinephrine
and serotonin.
Selegiline slows the breakdown of dopamine, thereby prolonging the clinical effects of levodopa.
Some studies show that selegiline may slow the progression of Parkinson's disease.
Benztropine is an antimuscarinic drug that may improve the tremor and rigidity of parkinsonism,
although it has little effect on the bradykinesia. It is thought to help maintain the balance of cholinergic and dopaminergic neurotransmission in the neostriatum.
Bromocriptine and pergolide are both dopamine receptor agonists.
Levodopa is the most effective drug for the treatment of Parkinson's disease and is the mainstay of treatment. Levodopa is a dopamine precursor that increases circulating dopamine levels in the striatum.
#3
Re: Pharmacology question #3 babbu5508 - 07-31-10 18:32 MAO inhibitors like selegiline or COMT inhibitors are the drugs which decrease the metabolism of dopamine and increase their levels..
#5
Re: Pharmacology question #3 babbu5508 - 08-29-10 00:52 parkinson's disease is due to loss of dopaminergic neurons in the nigrostraital pathway causing unopposed excess cholinergic activity
#8
Re: Pharmacology question #3 babbu5508 - 09-24-10 06:39 Microinvasive cancer (stage IA) is usually treated by hysterectomy (removal of the whole uterus including part of the vagina). For stage IA2, the lymph nodes are removed as well. An alternative for patients who desire to remain fertile is a local surgical procedure such as a loop electrical excision procedure (LEEP) or cone biopsy
#9
Re: Pharmacology question #3 babbu5508 - 09-24-10 06:40 MAO-B inhibitors (Selegiline and rasagiline) increase the level of dopamine in the basal ganglia by blocking its metabolization. They inhibit monoamine oxidase-B (MAO-B) which breaks down dopamine secreted by the dopaminergic neurons.
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