Exam 9: GI/CNS Flashcards
stomach protective mechanisms
bicarbonate - neutralizes H+ that penetrates the mucus
prostaglandins - stimulate secretion of mucus and bicarb
COX enzymes - prostaglandin synthesis?
antacids
aluminum, calcium, magnesium, sodium bicarb
decrease acidity by neutralizing w/ alkaline substances, decrease pressure on sphincters, increase good acid in stomach
magnesium: contra w/poor renal function, can cause diarrhea
aluminum - constipation
calcium - hypercalc & metabolic alkalosis
sodium - HTN & HF
take 1 hr apart from other medications because impacts absorption
cimetidine
H2 blocker - OTC - not recommended now
liver enzyme inhibitor -> can’t take w/ a lot of meds
crosses BBB -> CNS effects, antiandrogen effects -> gynecomastia, reduced libido, impotence
famotidine
H2 blocker - decrease the secretion of gastric acid
65% decrease in acid release
no liver enzyme inhibition -> less drug interaction, less ADRs
omeprazole/pantoprazole
PPI - decrease the secretion of gastric acid (sometimes for critically ill)
90% decrease in acid release (most effective) -> irreversibly blocks pump at parietal cells
ADR: long term -> PNA, osteoporosis (dec absorption of calc), rebound acid hypersecretion, hypomagnesemia (dec absorb), gastric cancer
teaching for ADRs: hypomag s/s (?), 30 min to 1 hr before eating (before breakfast)
sucralfate
indic: PUD, not GERD (sometimes for critically ill)
coats the ulcer and protects from acid
misoprostol
MOA: analog of prostaglandin (stimulates mucus and bicarb secretion)
NSAID related ulcers
off label for abortion
H. pylori treatment
most PUD caused by H. pylori (70%)
multiple abx + antisecretory agent (H2 or PPI) for 10-14 days
Clarithromycin
Amoxicillin
Metronidazole
Bismuth
Tetracycline
ondansetron
antiemetic - most effective (Zofran)
MOA: Serotonin 5HT3 receptor antagonist (disrupt the pathway to CTZ) and in the intestinal wall/stomach
PO, ODT, IV - uses: CINV, PONV, hyperemesis
ADR: drowsy, HA, diarrhea, QT prolong-> Torsades, serotonin syndrome
Education: rest, notify of pregnancy, notify of irregular HR
EKG - contra: Torsades, brady, blocks
haloperidol/droperidol
dopamine antagonists (butyrophenones)
PONV, CINV
ADRs: EPS, Sedation –> respiratory depression, hypo, prolong QT EKG
pull from other deck
dopamine antagonists ADRs
anticholinergic, sedation -> resp depress (promethazine) , EPS (haldol), tissue injury, hypo
metoclopromide
dopamine antagonists & prokinetic (empties stomach) (Reglan)
PONV, CINV (DM gastroparesis, GERD) contras: GI bleed, obstruct, perf
ADR: high doses -> sedation, diarrhea, EPS (tardive)
promethazine
dopamine antagonists (Phenergan) (phenothiazines)
IV, dark vial protected from light (filtered needle),
tissue injury at site (toxic), contra: less than 2 yrs
ADRs: sedation -> respiratory depression,
lorazepam
MOA: enhances GABA
CINV
methylprednisolone/dexamethasone
off-label use for CINV
used with arepitant or zofran
aprepitant
blocks neurokinin-type receptors in CTZ
unrelenting PONV & CINV -> delayed effectiveness
ADR: fatigue
dymenhydrinate/diphenhydramine
(Dramamine)/(Benadryl)
antihistamine for motion sickness, contra: glaucoma
ADRs: sedation, anticholinergic effects
admin 30-1hr prior to motion activity (as early as possible)
scopolamine
anticholinergic for motion sickness (most effective), contra: glaucoma
transdermal patch behind ear - apply 4 hours before activity
ADR: anticholinergic side effects (can’t see, can’t pee, can’t spit, can’t poop)
dronabinol/nabilone
cannabinoid - activates cannabinoid receptors near CTZ
CINV, used to stimulate appetite in patients w/AIDs
ADR: abuse potential, tachy, hypo, drowsy
controlled substance, avoid other CNS depressants
antidiarrheals
note if pt actually needs - often standing orders
E. coli - most common (cipro tx)
C. diff - metronidazole & vancomycin
bismuth subsalicylate
Pepto
antidiarrheal, antiemetic, PUD tx contra: pts w/coag disorders, kids w/viral febrile illness
educ: tarry stools, contains aspirin, OD=ringing in ear (aspirin tox)
Diphenoxylate with Atropine
antidiarrheal (lomotil)
diphenoxylate = opioid -> decrease intestinal motility (most effective)
atropine = added to counteract anticholinergic effects and make non addictive
sched V
Loperamide
antidiarrheal (immodium) - bulk forming
analog of meperidine but no narc or pain effect, doesn’t cross BBB
Polycarbophil/methycellulose
constipation tx -> same as dietary fiber (bulk-forming laxatives) (citrocel/metomucil)
sometimes used for diarrhea as well
take w/ 8oz H2O –> can solidify in GI tract w/o adequate liquids
contras: pts w/hypercalcemia for FiberCon
Docusate Sodium
constipation tx (stool softener) –> increases intestinal fluid secretion and inhibits reabsorption so stains in stool
prevent straining for BM often in hospital
Bisacodyl/senna
stimulant laxative -> irritates nerve endings in the intestinal mucosa to stimulate motility and fluid movement in bowel
PR: burning sensation, 6-8 hr onset
Magnesium hydroxide/sodium phosphate
(milk of mag) (fleet) osmotic laxative -> retains and draws water into lumen to soften feces
ADRs: substantial fluid loss, magnesium contra for renal, sodium contra for HF/HTN
educ: encourage to drink, renal function labs
lactulose
saline osmotic laxative
uses: constipation & hepatic encephalopathy -> known to pull serum ammonia into the bowel for excretion
Polyethylene Glycol
is bowel prep when combined with electrolyte solution
Golytely and Move-Prep
bristol stool chart
4 is ideal, want a 4-5 and don’t want to see 1-3 or 6-7
alosetron
IBS-D tx
slows down bowel, increases absorption of H2O and Na+, increases firmness of BM
ADRs: constipation, impaction, obstruction, ischemic colitis
orlistat
weight loss tx
inhibits gastric and pancreatic lipases to decrease absorption of fats
ADRs: oily rectal seepage, leaky flatulence, fecal urgency, vit deficiencies
carbedopa/levadopa
dopaminergic - converts to dopamine, crosses BBB
carbe allows more levo to enter brain (2% vs 10%) –> important because can give smaller dose and fewer ADRs
N/V, dyskinesia, psychosis, hypotens, dysrythmias
on-off phenomenon –> abrupt loss of effect
don’t eat high protein meals (spread throughout the day)
interacts w/ antipsychotics, MAOIs (HTN)
pramipexole
dopamine agonists - directly stimulates dopamine receptors
early/mild s/s, better absorption
no dyskinesias, but still hallucinations/daytime drowsy/postural hypo
entacapone
COMT inhibitors - blocks enzyme that inactivates dopamine
given w/ levodopa to be more effective (longer 1/2 life) and smaller doses
“stalevo” = levo/carbe/entacapone
ADRs: levo’s adrs
benztropine
anticholinergic - lowering acetylcholine compared to dopamine
reduces tremors/rigidity, not as effective as other agents
anticholinergic ADRs
selegiline
MAO-B inhibitor stops breakdown of dopamine
used alone or w/levodopa
start early in disease
large doses –> inhibit MAO-A as well (norepi & serotonin) –> also need to be careful of tyramine rich food (HTN crisis) and serotonin syndrome
amantidine
Parkinsons - MOA unclear, originally antiviral
Alzheimers
neurodegenerative, no cure
acetylcholine 90% below norm, neurofibrillary tangles, neuritic plaque
areas the control breathing and HR eventually destroyed –> death
Donepezil hydrochloride
acetylcholinesterase inhibitors (stop the enzyme that breaks down acetylcholine)
all levels of severity
ADRs: GI, dizzy, HA, bronchoconstriction, bradycardia (cholinergic effects)
avoid anticholinergic drugs (atropine, diphen, etc)
Rivastigmine
acetylcholinesterase inhibitors (stop the enzyme that breaks down acetylcholine)
for mild/moderate and don’t stop disease just help w/ s/s, stopped as disease progresses
same ADRs
Memantine
NMDA receptor antagonist
receptor triggered by excessive glutamate in Alzheimers that allows toxic levels of calcium into cell
MOA: slow/controls the influx of calcium into cells
only drug approved for severe s/s
ADRs: well tolerated, some dizzy, HA, confusion, constipation, hallucination
seizure causes
fever, epilepsy, genetic disorders, infx, hypoxia at birth, TBI, stroke, cancer
abnormal firing of cerebral neurons
decrease in GABA and increase in glutamate
febrile seizure tx
??
AEDs
start low & slow, only control seizures 60-70% of the time, CNS depress and should not be stopped abruptly, SI risk
suppress discharge of over-firing neurons and suppress propagation of seizure
important to monitor serum levels for most AEDs -> adjust dosage, monitor adherence, determine the cause when seizures happen, identifying cause of toxicity (polypharm)
meds must be taken at the same time - to maintain small therapeutic range
many are liver enzyme inducers –> decrease effect of other drugs
top class causes Steven-Johnsons (flu-like, then rash)
alt tx when don’t work: vagus nerve stim, keto diet, neurosurg
Phenytoin
selective inhibition of sodium channels (influx)
very narrow range - 10-20 mcg/mL
ADR: gingival hyperplasia, rash, tissue damage at site, hypoten, dysrhy, teratogenic
toxicity - nystagmus, SJ synd, unclear thinking, diplopia, sedation, ataxia, cardiac depression
educ - soft toothbrush and dental appt
only dilute w/NS
Carbamazepine
suppression of sodium influx and potentiates GABA, less cognitive function effects than pheny
ADRs: rash, CNS (nystagmus, ataxia, sedation), bone marrow suppression (CBC), fetal harm, hypovolemia/natremia
oral contraceptives - need alternative decreases efficacy
warfarin - decreases effect, higher risk of clot
grapefruit - toxicity
Valproic acid
suppression of calcium influx, increases availability of GABA
broad spectrum of effectiveness (v for variety) –> all types of seizures
ADRs: GI, highly teratogenic, hepatotoxic and pancreatitis, hyperamonemia
Fosphenytoin
converts to phenytoin when metabolized
IV/IM - short term use for status eplilepticus
same ADRs as phenytoin
cardiac monitoring
Ethosuximide
suppression of calcium influx
indic: absence seizures
don’t stop abrupt, monitor closely
Phenobarbital
MOA: potentiates and mimics GABA
generalized and partial seizures, rarely used due to significant ADRs
fetal harm
Levetiracetam (Keppra)
MOA unknown, binds w/ GABA
widely used in acute care PO/IV, not for absence, off label for migraine, bipolar
least amount of ADRs and risk of abuse or dependence, mild drowsy/weak/CNS, safe in pregnancy
Lamotrigine (Lamictal)
blocks sodium and partially calcium, good for all types, also used bipolar
ADRs: CNS, teratogenic, derm, risk for SI -> increased behavior monitoring
Pregabalin (Lyrica)
analog of GABA –> inhibits calcium influx
ADRs: dizzy, sedation, blurred vision, hypersensitivity, abuse/dependence
dc slowly, avoid other CNS depressants
Topiramate (Topamax)
risk for SI
Gabapentin (Neurotin)
approved by FDA for partial seizures, analog of GABA, mostly for off-label like nerve pain
ADRs: well tolerated but, somnolence, nystagmus
no drug interactions
Oxycarbazepine(Trileptal)
most common of newer AEDs
gen and part seizures, blocks sodium channels, more expensive than older AEDs but better tolerated
ADRs: CNS, hypoNa, hypothyr, bone marrow suppression, rash/SJ, hypersens
status epilepticus treatment
LOC, tachy, HTN, fever, hypoglycemic, acidotic, hypoxic
immediate: airway, rescue med, hypoglycemia
IV –> glucose, AED, benzo (lorazepam)
migraines
etiology not known (no identifiable cause), but vessel dilation causes pain
CGRP increased (vasodilate & inflame), S5HT decreased (protective)
estrogen help only hormone related
sumatriptan
1st line for abortive, constricts intracranial vessels, PO/SQ/IN/transdermal (PO fastest onset <30 min, SQ=30 min, IN = <60 min)
MOH - medication overuse HA, turns episodic HA into chronic from too many abortive meds
ADRs: heavy arms/chest pressure, coronary vasospasm, teratogenic; contra: CAD/HTN
sero syn w/ SSRIs
opioids
INH agent
migraine lasts longer, so have to take more and more, MOH (acute -> chronic HAs)
ergotamine
2nd line abortive, PO/IN/sublingual/PR; contras: CAD/HTN/PVD
N/V (admin w/antiemetic), risk of dependence, rebound headaches, vasoconstrict and HTN w/triptans
OD = sever tissue ischemia in the periphery from constriction (gangrene)
ubrogepant
CGRP antagonist, very expensive
preventative migraine treatment
bblkrs (propanolol), TCAs, AEDs - get put on if more than 2 migraines a month
Serotonin receptor agonist
botox
preventative, can reduce # and severity of migraines
