Drugs Used In Parkinsonism Flashcards
What happens in Parkinson’s disease?
●Progressive degenerative disease of the CNS of unknown etiology.(idiopathic)
●Affects mostly men over 65 years.
●The main problem is located in the extrapyramidal system.
●Destruction of the dopaminergic neurons in the substancia nigra and
●Decrease of the dopamine level in the neostratium.
What mainly happens in the disease Parkinsonism?
●Leads to reduction of dopaminergic inhibitory influence.
●Predominance of the acetylcholine exciting action.
What are the manifestations of Parkinsonism?
●Tremor
●Skeletal muscle rigidity (Increase their tone)
●Bradykinesia (slow movements)
●Patients often die as a result of long immobility.
(Pneumonia or thrombosis)
What drugs will cause Parkinsonism?
Treatment?
●Antipsychotics - haloperidol
□Reversible complication of the treatment with dopamine receptor antagonists.
Classify antiparkinsonian drugs?
●Drugs, that increase the activity of the dopaminergic system:
- dopamine precursor (levodopa) & dopaminergic receptor agonists
(bromocriptine)
- drugs increasing release and decreasing reuptake of dopamine
(amantadine). - MAO inhibitors (selegiline)
- COMT inhibitors (tolcapone)
●Drugs, that reduce the activity of the cholinergic system
(trihexyphenidyl).
What is the most effective drug for Parkinsonism?
●Levadopa (Suitable for monotherapy)
▪︎L-isomer of dihydroxyphenylalanine,
▪︎Dopamine precursor.
How to use levodopa?
●Penetrates through the blood-brain barrier and eliminates the deficiency of dopamine in the basal ganglia.
●The problem is that the part of levodopa is converted into dopamine outside the CNS,
●this is accompanied with both increasing of the severity of side effects and decrease of the efficacy.
●Therefore, used only in combination with a peripheral decarboxylase inhibitor
▪︎carbidopa
▪︎benserazide
(Trade names of such combined drugs are Sinemet, Madopar)
Side effects of levodopa? & their types?
●The side effects of levodopa are frequent and often serious.
●They are divided into two groups:
▪︎peripheral
▪︎central
Peripheral side effects of levodopa?
●Gastrointestinal
▪︎anorexia
▪︎nausea
▪︎vomiting
●Cardiovascular disorders
▪︎orthostatic hypotension
▪︎tachyarrhythmias
Central side effects of levadopa?
●Dyskinesia
●Mental disorders
▪︎anxiety
▪︎depression
▪︎aggressiveness
▪︎hallucinations
▪︎euphoria
Does levadopa causes on-off syndrome?
How will it happen?
●Yes,
●Change of akinesia on hyperkinesia & vice versa.
●Caused by - dopamine level fluctuations in the CNS &
Respective changes in the muscle tone.
Bromocriptine?
●Agonist of D₂ receptors.
●It is less effective, but safer
than levodopa.
●Bromocriptine can be used in combination with the latter.
Amantidine?
●The fast disappearance of the
therapeutical effect.(Main disadvantage)
●It is less effective than levodopa.
●Amantadine can be used in combination with the latter.
●The main side effects are,
▪︎mental,
▪︎dermatological
▪︎gastrointestinal disorders,
▪︎seizures.
Selengiline?
●Inhibits MAO
(monoamine oxidase - enzyme, which destroys dopamine)
●Increases dopamine level in brain.
●Used only in combination with other antiparkinsonian drugs.
Tolcapone?
●Inhibits COMT
(catechol-O-methyltransferase - enzyme)
(Which destroys dopamine)
