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Step 1: Neurology Rx

Terms in this set (109)

What is the mechanism of action of Phenytoin?
Use dependent blockade of Sodium channels increasing the refractory period, inhibition of glutamate release. Also decreases the flow of calcium ions. zero order kinetics.

also: Class IB antiarrhythmic
Which epilepsy drugs are Na+ channel inactivators
salt on your PCL
Phenytoin
Carbamazepine
Lamotrigine
What toxicity does Phenytoin have?
PHENYTOIN:
P: P-450 interactions H: Hirsutism E: Enlarged gums (gingival hyperplasia) N: Nystagmus Y: Yellow-browning of skin T: Teratogenicity: fetal hydantoin syndrome (cleft-lip, hear issues) O: Osteomalacia due to decreased Vit D absorption I: Interference with folic acid absorption (hence anemia)-megaloblastic N: Neuropathies: vertigo, ataxia, headache Lupus like symptoms, Lymphadenopathy, Stevens-Johnson Syndrome
What side effect does Carbamazepine have?
-agranulocytosis, aplastic anemia
- Stevens-Johnson syndrome
- SIADH → dilutional hyponatremia
- ↓ vitamin D absorption → vitamin D deficiency → osteomalacia
- Teratogenic effects: spina bifida, cleft lip/palate

CYP450 induction
What side effects does Lamotrigine have?
Severe rash, nausea, headache. Stevens-Johnson syndrome. MUST titrate slowly

call me if you get a rash!!
Which epilepsy drugs work by increasing GABAA action?
Levy break listening to LedZep w/ABA w/barbies and benzos

Levetiracetam
Tiagabine
Vigabatrin
Phenobarbital
Benzos (diazepam, lorazepam)
What is the mechanism of Gabapentin?
Designed as a GABA analogue, but primarily inhibits high-voltage activated calcium channels which may decrease glutamate and NE release.
What side effects does Gabapentin have?
Peripheral edema, sedation, ataxia. (Hepatotoxicity)
What side effects does Phenobarbital have?
Sedation, tolerance, dependence, induction of cytochrome P-450
Which drugs act both via Na inactivation and GABAa increased action?
Top! Valedictorian! Has it all!

Topiramate:
-Inhibits excitatory neurotransmission through action on AMPA/kainate subtype glutamate receptors
-Enhances GABA-activated chloride channels
-Sodium channel blocker

Valproate:
-Sodium channel inactivation. May affect potassium levels.
-Direct GABA agonist (by inhibiting GABA transaminase)
What side effects does Topiramate have?
kidney stones (due to a weak inhibition of carbonic anhydrase), somnolence and loss of appetite--weight loss, mental dulling
What side effects does Valproic acid have?
GI symptoms, rare but fatal hepatotoxicity, spina bifida in fetus (contraindicated in pregnancy), weight gain, thrombocytopenia, tremor
Which epilepsy drug is 1st line in neonates
Phenobarbital (barbie! for babies)
What enzymes should you measure with Valproic acid?
Liver enzymes due to fatal hepatotoxicity
What is the mechanism of action of Ethosuximide?
Blocks Thalamic T-type Calcium channels
What side effects does Ethosuximide have?
EFGHIJ

Ethosuximide causes Fatigue GI distress Headache Itching and SJS
Which anti-epilepsy drugs are CYP450 inducers?
Phenytoin, carbamazapine, phenobarbital
1st line for the following:
1. Partial seizures (simple and complex) 2. tonic clonic 3. absence 4. status epilepticus 5. eclampsia 6. neonates 7. bipolar + seizures 8. trigeminal neuralgia 9. postherpetic neuralgia 10. absence + tonic clonic
1. Partial seizures (simple and complex)- Carbamazpine 2. Tonic clonic- Phenytoin, Carbamazepine, Valproic acid 3. Absence- Ethosuximide 4. Status epilepticus- 1st benzo, then phenytoin= be no phenny 5. Eclampsia- MgSO4 6. Neonates- Phenobarbital 7. bipolar + seizures valproate 8. trigeminal neuralgia carbamazepine 9. postherpetic neuralgia gabapentin 10. absence + tonic clonic valproate
What are the Barbiturates?
Phenobarbital, Pentobarbital, Secobarbital

Thiopental!!!
In what condition are Barbiturates contraindicated in?
Porphyria
What is the clinical use of Barbiturates?
Anxiety, seizures, insomnia, induction of anesthesia (thiopental)
What side effects do Barbiturates have?
Respiratory and cardiovascular depression, CNS depression (can be exacerbated with alcohol use), dependence, drug interactions, induces P-450 System.
How is an overdose of Barbiturates treated?
Supportive, assist with respiration and maintain blood pressure
What are the five drug types that can treat Glaucoma?
Alpha-agonists, B-blockers, Diuretics, Cholinomimetics, and Prostaglandins
What are the alpha-agonists used to treat Glaucoma? mechanism? contraindications? side fx?
Decrease aqueous humor synthesis via vasoconstriction:

Epinephrine (alpha-1) not ok for closed angle b/c mydriasis

Brimonidine (alpha-2) "brim of your eye"

side fx: Blurry vision, ocular hyperemia, foreign body sensation, ocular allergic reactions, ocular pruritus. really only ones with all these eye issue side fx
What are the B-blockers used to treat Glaucoma? MOA?
Decrease aqueous humor synthesis

Timolol, Betaxolol, and Carteolol

(Tim is crying at the Beta Block Cart)
(Timolol, Glaucoma, Betaxolol, Beta Block, Carteolol)
What diuretics are used to treat Glaucoma? MOA?
Acetazolamide

Decreases aqueous humor synthesis via inhibition of carbonic anhydrase
What direct cholinomimetics are used to treat Glaucoma?
Pilocarpine and Carbachol

(You'll Cry [glaucoma] if you eat a Pile'O'Crap in an emergency b.c of the Direct Carbs)
What indirect cholinomimetics are used to treat Glaucoma?
Physostigmine and Echothiophate

(You can't see with stigma and echos, it's too indirect)
How do cholinomimetics work to treat Glaucoma?
Increase the outflow of aqueous humor via contraction of ciliary muscle and opening of trabecular meshwork
When do you use Pilocarpine? side fx?
In emergencies, very effective in opening meshwork into canal of Schlemm

side fx: Miosis and cyclospasm (contraction of ciliary muscle)
What Prostaglandin is used to treat Glaucoma? side fx?
Latanoprost a PGF2-alpha agonist

Darkens color of iris (browning, latanoprost) and can lengthen eyelashes

(LA tan produced frats, 2 alpha males with long eyelashes)

Be sure to remember that this is a prost = PG analog in case a different prost is given
What are the opioid analgesics?
Morphine, Fentanyl, Codeine, heroin, methadone, meperidine, dextromethorphan, diphenoxylate.
What is the mechanism of action of opioid analgesics?
Act as agonists of opioid receptors to modulate synaptic transmission- open Potassium channels, close calcium channels, and decrease synaptic transmission.
Match the 3 opioid receptors with their respective opiod peptides
mu = morphine (UM)
delta = enkephalin (DElta)
kappa = dynorphin (KD)
What do opioids inhibit the release of?
"PANGS" Substance P, ACh, NE,Glutamate, Serotonin
Which opioid can be used for cough suppression
Dextromethorphan

(meth orphans dont cough)
Which opioids can be used to treat diarrhea? How?
Loperamide and Diphenoxylate
by acting on the mu receptor in the GI tract, slowing motility

(don't poop at the opera, lo-operamide)
(stop the hen from pooping oxy= diphenoxylate)
What toxicity do opioids have?
Addiction, respiratory depression, constipation, miosis, additive CNS depression with other drugs.

biliary colic b/c can cause SM contractoin @ Oddi
Which opioid can act as an antagonist? side fx to consider?
Pentazocine is a partial agonist and a weak antagonist
Butorphanol is also partial u agonist, k agonist

When given to a patient that is dependent upon opioids, morphine, it will produce withdrawal fx
What two side effects of opioids don't develop tolerance?
Miosis and constipation.
What is opioid toxicity treated with?
Naloxone, or naltrexone (opioid receptor antagonist)
Maintenance programs from heroin addict consist of what?
Methadone
or
Buprenorphine + naloxone

b/c long half life and high potency- helps with withdrawal symptoms, good oral bioavailability
What is the mechanism of Butorphanol? use?
Kappa-opioid receptor agonist and Mu-opioid receptor partial agonist

produces analgesia

Severe pain (migraine, labor, etc). Causes less respiratory depression than full opioid agonists
What is the problem with Butorphanol overdose?
It is not easily reversible with naloxone.
What is the mechanism of tramadol? use? tox?
Very weak opioid agonist. Also inhibits serotonin and norepinephrine reuptake.

(Tram it all in with tramadol)

for Chronic pain

tox = Similar to opioids, can decrease seizure threshold.
Serotonin syndrome
What are the Benzodiazepine? MOA?
Diazepam, Lorazepam, Triazolam, Temazepam, Oxazepam, Midazolam, Chlordiazepoxide, Alprazolam

Ben likes it more frequently

Facilitate GABA-A action by increasing the frequency of Chloride Channel opening= Cl influx= hyperpolarization.
Decrease REM sleep.
Most have long half-lives.
Which Benzo's are short acting?
Triazolam, oxazepam, midazolam, alprazolam. Have a higher addictive potential.

"ATOM is small (short acting)"

Good for insomnia quick treatment
What is the clinical use of Benzo's?
Anxiety, Spasticity, status epilepticus, detoxification, night terrors, sleep walking, general anesthetic, and hypnotic (insomnia)
Which Benzo's are preferred for status epilepticus?
Lorazepam and Diazepam
What kind of anesthetic properties do Benzo's have?
Amnesia and muscle relaxation.
Midazolam use IV.
What toxicity do Benzos have? tx OD?
Dependence, additive depression effects with alcohol. Less risk of respiratory depression than with barbiturates. don't give with other sedatives.

Flumazenil. Competitive antagonist at GABA benzodiazepine receptor.
Which benzos can you use for pt with liver disease?
Out The Liver

Oxazepam Temazepam Lorazapam
What are the nonbenzodiazepine hypnotics? use? MOA? OD tx?
*Z*olpidem, ZaleploZolpidem, *Z*aleplon, Eszoiclone

Insomnia. Zolpidem is good for initiating sleep, and zaleplon is good for maintaining sleep.

MOA: Act via a BZ1 subtype of the GABA receptor.

Yes via Flumazenil
What anesthetic effect do drugs with decreased blood solubility have? Ex?
Rapid induction and recovery times. Low blood/gas partition coefficient.

Example: N2O
What anesthetic effect do drugs with increased lipid solubility have? Ex?
Increased potency. High blood/gas partition coefficient.

Example: Halothane
What does MAC mean? what does it vary with?
Minimal Alveolar Concentration at which 50% of the population is anesthetized.

Varies with age.
What are the inhaled anesthetics?
Halothane, Enflurane, isoflurane, Sevoflurane, methoxyflurane, and NO2

Halothane, NO2, "flurane"
What effects do inhaled anesthetics have?
Myocardial depression, respiratory depression, nausea/emesis, increase cerebral blood flow by decreasing cerebral metabolic demand, increase ICP
What toxicity do inhaled anesthetics have?
Malignant Hyperthermia inherited susceptibility

(except for Nitrous Oxide)
What toxicity does Halothane have?
Hepatotoxicity- necrosis, decreases hepatic BF, rarely given to adults, presents 2d-4wk after surgery, fulminant hepatitis- shrunken liver
What toxicity does Methoxyflurane have?
Nephrotoxicity b/c decreases GFR and increases renal vascular resistance
What toxicity does Enflurane have?
Proconvulsant
What toxicity does nitrous oxide have?
Expansion of trapped gas in body cavity
Tx for malignant hyperthermia
Cool, sedate, give dantrolene for muscle relaxation to prevent Ca2+ release from SR of skeletal muscle
What causes malignant hyperthermia?
Inhaled anesthetics (except N2O), succinylcholine

This is an inherited condition= RYR1 mutation which releases too much Ca2+ when given anesthetics
What are the intravenous anesthetics?
Barbiturates, Benzos, Arylcyclohexylamines (ketamine), Opioids, Propofol.

(BB King on Opioids Proposes)
What kind of drug is thiopental? what is it used for and why? Why does the thiopental effect terminate so quickly? Where does it redistribute? What effect does Thiopental have on cerebral blood flow?
Induction of anesthesia and short surgical procedures. High potency and lipid solubility with rapid entry into the brain.

B/c it redistributes in skeletal muscle and adipose tissue!

Decreases cerebral blood flow
Benzo vs Barbituate MOA
Benzo increases frequency of Cl GABA

Barb Keeps Cl- GABA open longer, increases the inhibitory effects of GABA

Ben likes it frequently
Barb likes it longer
Which Benzo is commonly used for endoscopy?
Midazolam
What is the mechanism of Arylcyclohexylamines?
Ketamine. PCP analogs that act as dissociative anesthestics. Block NMDA receptors.
What side effects does Ketamine have? What effect does Ketamine have on cerebral blood flow?
Cardiovascular stimulant. Can cause disorientation, hallucinations, and bad dreams.

Increases cerebral blood flow so don't use in neurosurgery
Which opioids are using in anesthesia?
Morphine and fentanyl during general anesthesia.
What is the mechanism of Propofol? What is Propofol used for?
Potentiates GABA-A, need a drip to maintain the anesthesia
Sedation in the ICU, rapid anesthesia induction, and short procedures. Has less postoperative nausea than thiopental.
What are the ester local anesthetics?
Procaine, cocaine, and tetracaine

caine with only 1 i
What are the amide local anesthetics?
Lidocaine, Mepivacaine, bupivacaine

(amide's have 2 I's in them)
What is the mechanism of local anesthetics?
Block Sodium channels by binding to specific receptors on the inner portion of the channel.

Usually given with vasoconstrictors like epinephrine to enhance local action and decrease bleeding as well as decrease systemic concentration of the drug
What do local anesthetics preferentially bind to? How do local anesthetics enter the membrane?
Activated sodium channels, so most effective in rapidly firing neurons.

Enter in the uncharged form and then bind ion channels as charged form
What happens to local anesthetics in infected (acidic tissue)?
Alkaline anesthetics are charged and cannot penetrate membrane effectively. Will need more anesthetic.
What is the order of nerve blockade for local anesthetics?
Small myelinated> Small unmyelinated>large myelinated> large unmyelinated

(unmyelinated= sensory, myelinated=motor usually)
What is the order of sensory loss with local anesthetics?
pain, temperature, touch, and pressure
What toxicity do local anesthetics have?
CNS excitation, severe cardiovascular toxicity, hypertension, hypotension and arrhythmias.
What toxicity does benzocaine have?
Methemoglobinemia
What are the classes of neuromuscular blocking drugs?
Depolarizing = succinylcholine

Nondepolarizing = tubocurarine, atracurium etc.
How does succinylcholine help for surgery?
Strong ACh receptor agonist
Produces sustained depolarization with Na influx and K release, prevents muscle contraction
What are the phases of succinylcholine?
Phase 1 10min, prolonged depolarization, no reversal

Phase 2 20-30min- hours, ACh receptors are available but desensitized, can use cholinesterase inhibitors to reverse (neostigmine)
Succinylcholine complications
HyperCa2+
HyperK+
Malignant hyperthermia (RYR1)
What conditions are contraindicated with succinylcholine?
Myopathies, burns, G-B, denervation issues, b/c they have high nAChR so with succinylcholine bound, a large amount of K will be released dangerous hyperkalemia
How do the nondepolarizing neuromuscular drugs work? reverse?
Tubocurarine
Atracurirum etc.
Pancuronium etc.

Competitive antagonists, compete w/ACh for receptors

Reverse:
Neostigmine with atropine (to prevent muscarinic effects s/a bradycardia)
Edrophonium
Other cholinesterase inhibitors
Dantrolene MOA, use
Prevents release of Ca2+ from SR, relaxes muscle

tx malig hyperthermia, NMS
Baclofen MOA, use
Inhibits GABA-B at spinal cord level, inducing skeletal muscle relaxation

Used for muscle spasms, acute LBP
Cyclobenzaprine MOA, use, side fx
Centrally acting skeletal muscle relaxant, similar to TCAs

Used for muscle spasms

Side fx- anticholinergics
5 types of parkinson disease drugs w/ex
>DA agonist: Bromocriptine
>Increase DA availability: Amantadine
>Increase L-DOPA availability: Levodopa, capones
>Prevent DA breakdown: Selegiline, COMTi
>Curb excess cholinergic activity: Antimuscarinics, Benztropine

BALSA
Deep brain stimulation for parkinson disease should go where?
Subthalamic nucleus- to allow movement
Restless leg syndrome tx of choice
DA agonists= ropinorole, pramipexole
Which DA agonists are preferred from parkinson disease and why?
Non-ergots are preferred (pramipexole, ropinirole)

b/c the ergot (bromocriptine) causes peripheral vasoconstriction, increasing BP
Bromocriptine MOA, use aside from PD, side fx
DA agonist, ergot

Use: PD, prolactinoma

Peripheral vasoconstriction increasing BP
Amantadine MOA, use aside from PD, side fx
Increases DA release and decreases reuptake (increases availability)

Use: PD, antiviral vs influenza A and rubella

Side fx: ataxia, livedo reticularis (lace)
L-Dopa MOA, side fx, long-term
Increases L-Dopa availability:
inhibits DOPA decarboxylase

side fx: >anxiety b/c increasing DA in brain
>arrhythmias from increased peripheral formation of catecholamines

longterm: "on-off" phenomnen, long-term use can lead to dyskinesia w/use and akinesia btwn doses, unpredictable
Entacapone MOA
Increases L-Dopa availability:
inhibition of COMT= prevents peripheral L-dopa degradation into 3-O-methyldopa
Selegiline MOA, use
Prevents DA breakdown:
inhibition of MAO-B = block DA conversion to 3-MT

Selegeline acts on MAO-B which preferentially metabolizes DA over NE/5HT = increased DA

Adjunctive agent to L-Dopa but may enhance the adverse fx of L-Dopa
Tolcapone MOA
Increases L-Dopa availability and prevents DA breakdown:
1- Inhibits central COMT = blocked conversion of DA to DOPAC
2- Inhibition of peripheral COMT= prevents peripheral L-dopa degradation into 3-O-methyldopa
Benztropine MOA, fx
Curb excess cholinergic activity:
Antimuscarinic (improves tremor and rigidity, little fx on bradykinesia)

Improves tremor and rigidity, Little effect on bradykinesia
What 2 mechanisms of drugs can be used to tx Alzheimers?
1- NMDA receptor antagonist (prevent excitotoxicity by reducing Ca2+) = Memantine

2- ACEi = Donepezil, galantamine, rivastigmine, tacrine
What ACEi are indicated for Alzheimers?
Donepezil
Galantamine
Rivastigmine
Tacrine

(Done Galanting Vastly want Talcon Meme)
Memantine MOA, use, side fx
NMDA receptor antagonist (prevent excitotoxicity by reducing Ca2+)

For Alzheimer

side fx: hallucinations, dizzy, confused

(Done Galanting Vastly want Talcon Meme)
What medications are indicated for Huntington disease?
Huntington results in decreased GABA and ACh, increased DA

Meds to tx excess movement and depression

Tetrabenzine, reserpine- inhibits vesicular monoamine transporter (VMAT) to limit DA vesicle packaging and release
Haloperidol- D2 receptor antagonist

(I got you an HD tv, 4 benzs and a serpent b/c i'm a halo angel)
Sumatriptans MOA (4), use, contraindications
1- Post-synaptic 5-HT1B/1D agonist
2- Inhibits trigeminal nerve activation
3- Prevents vasoactive peptide release
4- Induces vasoconstriction

migraine
cluster headaches

contraind: Can cause coronary vasospam: contraindicated in prinzmental angina, CAD
Benign essential tremor treatment
Primidone (this an anti-convulsant has phenobarbitol metabolites which can cause sedation and should be monitored)

PROPRANOLOL

Can use beta-blockers if primidone is not well tolerated
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