Pharmacology Flashcards
Entacapone
- COMT inhibitor (catechol-o-methyltransferase)
- Dopamine is metabolized by COMT –> 3-o-methyldopa
- by inhibiting conversion, it extends plasma half-life of dopamine
- administered concomitantly with levodopa
- increase duration of action of levodopa, reduce off periods
Levodopa
- dopamine precursor
- after ingestion, it is converted in the brain and peripherally to dopamine by dopa-decaroboxylase
- peripheral conversion –> SE (nausea & dyskinesias due to dose and duration of therapy); carbidopa inhibits peripheral conversion (that is why it is adminsitered with levodopa)
Pramipexole & Ropinirole
- dopamine agonists at D2 and D3 receptors
Rasagiline, Selegiline
- selective MAOB inhibitors (involved in dopamine metabolism)
- SE selegiline: insomnia (converted into methamphetamine)
Trihexyphenidyl
- anticholinergic
- treatment of tremor (thought to result from excess Ach)
- SE: cognitive dysfunction (esp older), constipation, dry eyes/mouth, urinary retention
Amantadine
- antiglutamatergic
- also used in treatment of PD
- increases presynaptic dopamine release, inhibits reuptake of synaptic dopmaine
Barbiturates
- phenobarb, pentobarb, thiopental, secobarbital
- facilitate GABAa action by increasing duration of Cl- channel opening, thus decreasing neuron firing
- OD can cause CNS depression, respiratory and cardiovascular depression, induces CYP 450
Benzodiazepines
- Diazepam, lorazepam, midazolam
- facilitate GABAa action by increasing frequency of Cl- channel opening
- most have long T1/2 (except midazolam)
- CNS depression, less risk of resp depression and coma than with barbiturates
- tx OD with flumazenil
Memantine
NMDA receptor antagonist; used for tx of alzheimers dementia (moderate-severe disease in adjunct to a AchE inhibitor, usually donepezil)
AchE inhibitors
Donepezil, galantamine, rivastigmine
- rivastigmine can also be used in Parkinson’s dementia
Pimavanserin
new 5-HT2A receptor inverse agonist that has been shown to reduce psychosis in Parkinson’s disease without worsening motor symptoms
Fingolimod
- acts on sphingosine-1 phosphate receptors (S1P1 receptor) –> decrease in release of lymphocytes
- first oral agent for treatment of MS
- side effects: macular edema, bradycardia
Antipsychotics associated with TD
fluphenazine and haldol
Drugs used to tx essential tremor
- combo of primidone and propranolol shown to be more effective than either alone (each reduces tremor by 50%)
- can also use topiramate, gabapentin, and benzo (clomazepam)
- in severely resistant cases, can consider DBS to ventra intermediate nucleus of thalamus
Tysabri (Natazulimab)
Monoclonal AB for relapsing MS
- MOA: selectively binds to alpha-4 subunit of integrin (cell adhesion molecule)
- reduces ability to inflammatory cells to cross BBB into CNS –> decreased inflammation
- need to screen for JC virus
Teriflunomide (Aubagio)
For RRMS
- selectively and reversibly inhibits DHOD (dihydroorate dehydrogenase) which is mitochondrial enz necessary for pyrimidine synthesis
- immunomodulatory effects which is useful in MS
- may cause transaminitis
Alemtuzumab (Lemtrada)
monoclonal AB useful for relapsing MS
- binds to CD52 (T and B lymphocytes)
- has serious side effects (emergency of 2/2 autoimmune dx)
- only approved to pts who have failed 2 other MS medications