Neuro Drugs Flashcards
Epinephrine, Brimonidine
alpha 2 agonists
- decreased aqueous humor synthesis
- SE (epi): mydriasis, do not used in closed-angle glaumcoma
- SE (brimonidine): blurry vision, ocular hyperemia, foreign body sensation, ocular allergic reactions, ocular pruritis
timolol, betaxolol, carteolol
beta blockers
- decreased aqueous humor synthesis
- no pupillary or vision changes
acetazolamide
carbonic anhydrase inhibitor
- decreased aqueous humor synthesis, no pupillary or vision changes
- SE: somnolence, paresthesias, urinary alkalosis
pilocarpine, carbachol
- direct cholinomimetics
- increase outflow of aqueous humor via contraction of the ciliary muscle and opening of trabecular meshwork
- SE: miosis and cyclospasm (contraction of ciliary muscle)
physostigmine, echothiophate
indirect cholinomimetics
- use pilocarpine in emergencies, very effective at opening meshwork into canal of Schlemm
- SE: miosis and cyclospasm (contraction of ciliary muscle)
latanoprost (PGF2a)
prostaglandin that increases outflow of aqueous humor
- darkens the color of the iris (browning)
opioid analgesics (names)
morphine, fentanyl, codeine, loperamide, methadone, meperidine, dextromethorphan, diphenoxylate
opioid mechanism
- acts as agonists at opioid receptors (mu = morphine, delta = enkephaline, kappa = dynorphin) to modulate synaptic transmission - opens K channels, closes Ca channels –> decreased transmission
- inhibit release of Ach, norepi, 5HT, glutamate, substance P
opioid clinical use
- pain
- cough suppression - dextrmethorphan
- diarrhea - loperamide, diphenoxylate
- acute pulmonary edema
- methadone maintenance for heroin addicts
opioid tox
- addiction, resp depression, constipation, miosis, additive CNS depression with other drugs
- tolerance does not develop to miosis and constipation
- uncommon: RUQ pain bc morphine causes smooth muscle contraction –> sphincter of oddi contraction
- tox treated with naloxone or naltrexone
butorphanol
mech: mu-opioid receptor partial agonist and kappa-opioid receptor agonist, produces analgesia
- used in severe pain, causes less respiratory depression than full agonists
- can cause opioid withdrawal if the patient is also taking a full agonist
- overdose not easily reversed with naloxone
tramadol
- very weak opioid agonist, also inhibits serotonin and norepi reuptake
- used in chronic pain
- tox: similar to opioids, decreases seizure threshold, serotonin syndrome
pentazocine
opioid narcotic with partial agonist activity and weak antagonist activity at mu receptors
- can cause withdrawal in a dependent person
ethosuximide
- used in absence seizures
- blocks thalamic T-type Ca channels
- side effects: GI, fatigue, headache, urticaria, SJS
- “sucks” to have silent seizures
phenytoin
- used in all seizure types except absence, can be used in status
- increase Na channel inactivation, zero-order kinetics
- nystagmus, diplopia, ataxia, sedation, gingival hyperplasia, hirsuitism, peripheral neuropathy, megaloblastic anemia, teratogen, SLE-like syndrome, induction of cytochrome P-450, lymphadenopathy, SJS, osteopenia
carbamezapine
- used in all types of seizures except absence
- increases Na channel inactivation
- SE: diplopia, ataxia, blood dyscrasias, liver tox, teratogenesis, induction of P-450, SIADH, SJS
- 1st line treatment for trigeminal neuralgia
valproic acid
- used in all types of seizures, 1st line in T-C seizures
- increases Na channel inactivation, increased [GABA] by inhibiting GABA transaminase
- SE: GI distress, rare but fatal hepatotox (measure LFTs), neural tube defects, tremor, weight gain
- also used for myoclonic seizures and bipolar disorder
gabapentin
- used in all types except absence seizures
- primarily inhibits high-voltage-activated Ca channels, designed as GABA analog
- SE: sedation, ataxia
- also used for peripheral neuropathy, postherpetic neuralgia, migraine prophylaxis, bipolar disorder
phenobarbital
- used in all types except absence seizures
- increased GABAa action
- SE: sedation, tolerance, dependence, induction of P450, cardiorespiratory depression
- 1st line in neonates
lamotrigine
- used in all types of seizures
- blocks voltage gated Na channels
- SE: SJS
barbituates (phenobarb, pentobarb, thiopental, secobarbital) mech and use
- mech: facilitate GABAa action by increasing duration of Cl channel opening, thus decreasing neuron firing
- contraindicated in porphyria
- used as sedative for anxiety, seizures, insomnia, induction of anesthesia (thiopental)
whats so special about thiopental?
rapidly wears off due to distribution into tissues, not because of metabolism
- barbituate used for induction of anesthesia and short surgical procedures
barbituates toxicity
- resp and cardiovascular depression
- CNS depression, dependence, drug interactions (p450 inducer)
- overdose treatment is supportive
long acting benzos
diazepam, flurazepam, chlordiazepoxide
intermediate acting benzos
LET
lorazepam, estazolam, temazepam
short acting benzos
TOM
- triazolam, oxazepam, midazolam
benzo mechanism
- facilitate GABAa action by increasing the frequency of Cl channel opening
- decrease REM sleep
benzo tox
- dependence, additive CNS depression effects with alcohol
- less risk of respiratory depression and coma than with barbituates
- treat overdoses with flumazenil (competitive GABA antagonist)
nonbenzo hypnotics
- zolpidem, zaleplon and eszopiclone
- act via the BZ1 subtype of the GABA receptor, effects reversed by flumazenil
- used for insomnia
- metabolized by p450
- tox: ataxia, headaches, confusion, short duration and only modest day-after psychomotor depression
- decreased risk of dependence, no muscle relaxing or anticonvulsant effects
MAC
minimal alveolar concentration
- lower MACs, higher potency
- drugs with increased solubility in lipids –> increased potency = 1/MAC
inhaled anesthetics names and effects
- halothane, enflurane, isoflurane, sevoflurane, methoxyflurane, NO
- mechanism unknown
- effects: myocardial depression, respiratory depression, nausea/emesis, increased cerebral blood flow, decreased cerebral metabolic demand, decreased GFR, decreased hepatic blood flow
inhaled anesthetics side effects
- hepatotox (halothane), nephrotox (methoxyflurane), proconvulsant (enflurane), expansion of trapped gas in body cavity (NO)
- can cause malignant hyperthermia, treat with dantrolene (usually due to ryanodine receptor mutation, this prevents further release of Ca)
midazolam
- most common drug used for endoscopy
- used adjunctively with gaseous anesthetics and narcotics
- may cause severe postop resp depression, decreased BP and anterograde amnesia
ketamine
- PCP analog that acts as a dissociated anesthetic
- blocks NMDA receptors
- CV stimulant
- causes disorientation, hallucination and bad dreams
- increased cerebral blood flow
propofol
- used for sedation in the ICU, rapid anesthesia induction, and short procedures
- less post op nausea than thiopental
- potentiates GABAa
local anesthetics
- block Na channels by binding to specific receptors on the inner portion of the channel
- need more in infected (acidic) tissue
- blocks small myelinated fibers > small unmyelinated fibers > large myelinated fibers > large unmyelinated fibers
- lose pain, then temp, then touch, then pressure
- tox: CNS excitation, cardiovascular tox, HTN, hypotension, arrhythmias
succinylcholine
- strong Ach receptor agonist
- produced sustained depolarization and prevents muscle contraction
- reversal of blockade not possible in phase I, cholinesterase inhibitors will overcome blockade in phase II (when the receptors are available but desensitized)
nondepolarizing neuromuscular blocking drugs
- tubocurarine, atracurium, mivacurium, pancuronium, vecuronium, rocuronium
- competitive antagonists, compete with Ach for receptors
- reversal of blockade with neostigmine, edrophonium and other cholinesterase inhibitors
dantrolene
- prevents release of Ca from the sarcoplasmic reticulum of skeletal muscle
- used to treat malignant hyperthermia and NMS because usually due to ryanodine receptor mutation
bromocriptine, pramipexole, ropinirole
dopamine agonist used in parkinsons
amantadine
increases dopamine release, also has antiviral activities
- tox: ataxia
selegiline
- selective MAOb inhibitor that prevents dopamine breakdown
- adjunctive agent to L-dopa in treatment of parkinsons
- may enhance adverse effects of L-dopa
entecapone, tolcapone
- COMT inhibitors that prevent L-dopa degredation
- entecapone inhibits peripheral destruction, and tolcapone inhibits peripheral and central destruction
benztropine
- antimuscarinic that improves tremor and rigidity in parkinsons but has little effect on bradykinesia
memantine
- NMDA receptor antagonist
- helps prevent excitotoxicity (mediated by Ca)
- tox: dizziness, confusion, hallucinations
donepezil, galantamine, rivastigmine
- AchE inhibitors used in alzheimers
- tox: nausea, dizziness, insomnia
Huntington drugs
- NT changes: dec GABA and Ach, inc dopamine
- haloperidol - D2 receptor antagonist
- tetrabenazine and reserpine - inhibit vesicular monoamine transporter, limit dopamine vesicle packaging and release
sumatriptan
- serotonin agonist
- inhibits trigeminal nerve activation, prevents vasoactive peptide release, half-life < 2 hours
- used in acute migraine and cluster headaches
- tox: coronary vasospasm (contraindicated in pts with CAD and prinzmetal angina), mild tingling
