Pharmacology of Neurodegenerative diseases, epilepsy and migraine Flashcards
what are the someone symptoms for parkinsons disease
progressive disease
tremor of rest
bradykinesia, rigidity
postural defect: tendency to stoop
what is the mortality of parkinsons disease
due to complications of severe rigidity
what is the pathophysiology of parkinsons
progressive degeneration of neurons in the substantia nigra: loss of DA transmission
leads to imbalance of input to the cortex - DA/ACh balance
what medication can quickly produce parkinsonian symtpoms
injection of MPTP
(a neurotoxin that kills dopamine-producing neurons)
what are the classes of dopamine receptors
D1 receptors (excitatory) and D2 receptors (inhibitory)
what is the effect of D1 receptor class
Excitatory
Increase cAMP
PIP hydrolysis
Ca2+ mobilization and PKC activation
what is the effect of D2 receptor class
Inhibitory
decrease cAMP
increase K+ currents
decrease Ca2+ currents
what does parkinsons inhibit
the thalamus and reduces thalamic stimulation of the cortex
What is the goal of Parkinson therapy
re-establish balance of striatal signaling
increase DA signaling and Decrease mACh signaling
what type of medication is levodopa
DA precursos
what is the MOA of levodopa
crosses the BBB
actively taken up into neurons (amino acid transporter)
converted to DA by DA decarboxylase
what are the adverse effects of Levadopa
dyskinesia
hallucinations/confusion (cautiously treat psychosis with antipsychotics)
peripheral effects: Nausea, hypotension, arrhythmia
why can Levadopa cause Nausea
DA receptors in the gut are affected
What is Carbidopa
adjunct therapy - peripheral inhibitor of levadopa (l-aa decarboxylase)
what is the purpose of Carbidopa
prevents conversion to DA in periphery
does NOT cross the BBB
reduces peripheral side effects (nausea) and allow more drug to reach the brain
what is the mainstay treatment for parkinsons disease
Levodopa-Carbidopa
what is Entacapone
a levodopa adjunct therapy - inhibits COMT enzyme mostly in the periphery
prevents degradation of Levodopa
what is COMT
catechol-o-methyl transferase
secondary pathway to metabolize levodopa as well as DA and NE
what are the adverse effects of Entacapone
dyskinesia, nausea and diarrhea
what is the efficacy of levodopa
extremly effective early in treatment
overtime one may develop motor flunctuation
how is motor fluctuation effect reduced
by increasing number of dosages
what is the benefit of increasing the number of levodopa dosages
to decrease motor fluctuation
what is the MOA Selegiline
Beta inhibitor that prevents metabolism of DA
selective for striatum, mild effect
reduced the dose of devodopa needed
what is another beta inhibitor that can be used for parkinsons treatment
Rasagiline
what are the adverse effects of selegiline
some amphetamine - like side effects (partly metabolized to amphetamine)
possibility of serotonin syndrome
what is the metabolism of selegiline
metabolized in the liver by CYP450 enzymes
possible serotonin syndrome induced by foods containing tyramine or combining with SSRIs or CYP450 substrates
what is a dopamine receptor agonist medication
Bromocriptine
Ropinerole
(pramipexole, perogolide, apomorphine)
what is Bromocriptine
DA receoptor agnoist: ergot alkaloid - D2 receptor agnoists
some avitivty at D1, D3 and 5-HT receptors
used to delay the need for using levodopa and also for advanced parkinsons
what are the side effects of Bromocriptine
more risk of psychotic effects and risk of cardiac valve fiborsis in long-term use
what is Ropinerole
dopamine receptor agonist
less selective than bromocriptine has D2, D3, D4 receptor agonist receoptos
what is ropinerole also beneifical in treating
restless leg syndrome
what are the adverse effects of ropinirole
metabolized by CYP450 thus could cause drug interaction
mostly has replaced bromocriptine therapeutically due to reduced side effects - less risk of cardiac valve fibrosis and D3 agonisms is linked to increased risky behavior
the agnoism of D3 is linked to what
increased risky behavior (gambling, hypersexuality)
what are non-DA parkinson treatments
MACh receptor agonists and antivirals
what is trihexyphenidyl
mACh receptor agonists
effective at reducing dyskinetic movements and spastic contractions - often given in combination with DA agonists
what is another option for mACh receptor agonists that is less commonly used
Benztropine
what are the adverse effects of trihexyphenidyl
anticholinergic side effects: sedation, confusion, constipation, urinary retention
pharmacokinets: excreted unchanged
what is amantadine
anti-viral drugmechanism by increaseing DA release and blocking NMDA gluamate receptors
less effective than levodopa
what may amatadine casue
confusion/psychosis
what is huntinggtons disease
dominant inherited disorder characterized by involunatary movements, personality changes and bradykinesia
what type of vulnerability does huntingtons disease have
selective,
mutant gene expressed throughout brain
neuronal loss is limited to caudate/putamen, striatum and loss of GABA function
what is the treatment for huntingtons
very difficult to treat becasuse of its effects on multiple neuronal systems
based on most pronounced symptoms: psychosis and chrea
what is the psychosis treatment for huntingtons
neuroleptic D2 blockers such as Haloperidol
what is the chorea treatment for huntingtons
inhibitor of neurotransmitter storage such as Deutetrabenazine
what is Deutetrabenazine
inhibitor of VMAT-2
prevents storage of neurotransmitter in vesicles
reduced uncontrolled hyperkinetic movements
where is Deutetrabenzine metabolized
P450 (CYP2D6)
some patient sare poor metabolizers
long half-life relative to tetrabenazine