HNN Flashcards
Selegiline
Selective MAO-B inhibitor
Used to treat PD
Prevents effects of MPTP neurotoxin
reduces breakdown of dopamine in the CNS, especially at the corpus striatum
Gold standard treatment for PD
Levodopa + Carbidopa
Carbidopa
- peripheral decarboxylase inhibitor
- prevents peripheral conversion of levodopa to dopamine by blocking dopa decarboxylase
- increases cerebral levodopa bioavailability and reduces the peripheral adverse effects of dopamine (e.g. nausea, hypotension)
- used to treat PD in combination with levodopa
- allows a much lower dose of levodopa (80% less)
NB: Motor complications develop in 50% of all PD patients after 6 years of levodopa therapy. disease continues to progress, and patients accumulate long-term disability
Levodopa
- most effective agent in the management of Parkinson’s symptoms
- precursor for dopamine, used because dopamine itself cannot cross the blood-brain barrier.
- Peripherally metabolised to dopamine and then to adrenaline/NA, which can cause altered blood pressure/nausea
- combined with carbidopa which blocks the conversion of levodopa to dopamine in the periphery, this allows a much lower dose of levodopa (80% less)
- avoid protein-rich meals (impair levodopa absorption - Dietary amino acids can inhibit active transport across the BBB by competing with levodopa)
Pramipexole
- D2/3 selective agonist
- used to treat PD
- may be used in combination with levodopa or as initial monotherapy in younger patients
- less effective in symptom control than levodopa and generally less well tolerated, but associated with fewer motor complications over a 5-year period.
- Domperidone is used as an antiemetic when initiating DA therapy
- Since Dopamine has various functions in brain, these agonists can act on other systems causing side effects such as hallucinations, compulsive behaviour (e.g. excessive gambling)
Ropinirole
- D2/3 selective agonist
- used to treat PD
- may be used in combination with levodopa or as initial monotherapy in younger patients
- less effective in symptom control than levodopa and generally less well tolerated, but associated with fewer motor complications over a 5-year period.
- Domperidone is used as an antiemetic when initiating DA therapy
- Since Dopamine has various functions in brain, these agonists can act on other systems causing side effects such as hallucinations, compulsive behaviour (e.g. excessive gambling)
Entacapone
- Catechol-o-methyltransferase (COMT) Inhibitor
- Used to treat PD
- reduces the peripheral metabolism of levodopa, making more levodopa available to enter the brain
- prolong dopamine activity by blocking breakdown.
Tolcapone
- Catechol-o-methyltransferase (COMT) Inhibitor
- Used to treat PD
- reduces the peripheral metabolism of levodopa, making more levodopa available to enter the brain
- active in periphery and brain
- prolong dopamine activity by blocking breakdown.
Memantine
inhibits glutamate by blocking NMDA receptors
Used in treatment of alzheimers
Donepezil
acetylcholinesterase inhibitor
Used in treatment of alzheimers
Rivastigmine
acetylcholinesterase inhibitor
Used in treatment of alzheimers
In which patients should antipsychotic drugs be avoided?
Dementia with Lewy bodies
causes hypersensitivity to neuroleptics
General mechanism of action of Anxiolytics and sedatives
cause sleep and reduce anxiety
Bind to the GABA-A receptor and potentiate the action of the endogenous receptor.
Upon activation, the GABA-A receptor selectively conducts Cl− through its pore, resulting in hyperpolarization of the neuron.
This causes an inhibitory effect on neurotransmission by diminishing the chance of a successful action potential occurring
Two main classes of anxiolytics and sedatives
barbiturates (eg pentobarbitone)
Benzodiazepines (eg diazepam)
antipsychotic drugs
drugs that are effective in relieving the symptoms of schizophrenic illness
