Week 3 Flashcards
What is the main opioid receptor out of the three known?
- u - opioid receptor
What are the overall effects of opioid analgesics? [sedative, analgesic, amnesic, etc]
sedative and analgesic
When do withdrawal sx of opioids start?
6-12 hours after last dose
What occurs when opioid analgesic activates u opioid receptor? (3)
- u opioid receptor interacts with G protein to change ion channel gating
- In neurons, opioid agents cause opioid receptors to open K+ channels → hyperpolarization (less pain signals)
- also causes closer of VG Ca2+ channels → this is on presynaptic neuron so NT are not released
How do opioids affect bowel movements?
- many u opioid receptors are located in GI tract → opioid agents cause delayed stool transit, increased water reabsorption, and overall constipation
at times opioids can be used to tx diarrhea
List some common
1. full u agonists
2. partial u agonists
3. opioids used for withdrawal sx
- fentanyl, morphine, codeine, methadone, hydrocodone, heroin, oxycodone, opium, etc
- buprenorphine, nalbuphine, butorphanol (“bu”)
- methadone, buprenorphine
List some common drugs that are
1. u antagonists
2. opioids used for diarrhea (do not cross BBB, have no analgesic properties)
- naloxone (narcan), naltrexone
- loperamide, diphenoxylate
Do opioids cause miosis or mydriasis?
miosis (pupil constriction)
What are the sx seen with opioid withdrawal
Rhinorrhea, Lacrimation, Yawning, Hyperventilation, Hyperthermia, Muscle aches, Vomiting, Diarrhea, Anxiety → **moist symptoms **
Why are methadone and buprenorphine used to help with opioid withdrawal sx?
- they have long half lives so when tapered off they don’t have extreme sx and are easier to manage for a pt
buprenorphine is partial u agonist ; methadone is full u agonist
What drug can mimic parkinson’s disease?
MTMP - it can destroy dopamine neurons and lead to drug induced parkinson’s
How does levodopa cause beneficial changes to patient with parkinsons? (MOA)
- Levodopa is precursor to dopamine and CAN cross BBB (unlike dopamine)
- Once inside brain/CNS, DOPA decarboxylase converts levodopa into dopamine for CNS use
Why is Carbidopa given with levodopa for parkinson’s patients
- DOPA decarboxylase converts levodopa into dopamine both in and outside the CNS.
- Since carbidopa doesn’t cross BBB - it works outside the CNS to inhibit DOPA decarboxylase and increase bioavailability of levodopa
What is the purpose of Entacapone and Tolcapone in parkinsons treatment?
- COMT converts levodopa to 3-OMD (thus decreasing levodopa bioavailability)
- Both of these drugs inhibit COMT
When is entacapone or tolcapone used over carbidopa
- usually tolcapone and entacapone are given after patient has used levodopa and carbidopa and is starting to experiencing on-off syndrome and wearing off reaction
What is the difference between entacapone and tolcapone?
- tolcapone works in both peripheral and central COMT
Major side effect of tolcapone that can make providers favor entacapone?
- hepatic failure
Side effects of levodopa?
1. with too much in periphery
2. too much centrally
3. chronic levodopa use (2)
- GI distress, N/V, cardiac arrhythmias, orthostatic hypotension
- Neurospychiatric sx like anxiety, agitation, insomnia, confusion, hallucinations
- Wearing off rx (at end of each dose) and on-off phenomenon (periods of akinesia with periods of improved mobility)
Why is levodopa contraindicated in psychiatric patients?
levodopa is contraindicated in psychotic patients because the method of treating psychotic patients is blocking CNS dopamine (too much dopamine in psychotic patients)
ex: schizophrenia
How is selegiline used for in parkinsons patients?
MOA: increases availability of dopamine in CNS by inhibiting MAO-B, which increases dopamine
- How is ropinirole used for in parkinsons patients?
- Side effects
- MOA: D2 dopamine receptor agonist
- can enhance impulse control disorders like gambling, shopping, hypersexuality
- How is pramipexole used for in parkinsons patients?
- Side effects
- MOA: D3 dopamine receptor agonist - an important initial tx
- can enhance impulse control disorders like gambling, shopping, hypersexuality
- How is amantadine used for in parkinsons patients?
- Why is it not used over levodopa
- MOA: enhances the effect of endogenous dopamine by increasing its synthesis/release and inhibiting its re-uptake
- Can alleviate dyskinesia sx but not as effective as levodopa and effects are short lived. Added as adjunctive to levodopa.
- How is trihexyphenidyl and benztropine used for in parkinsons patients?
- What sx does it improve and NOT IMPROVE in parkinsons?
- Side effects?
- MOA: Antimuscarinic agents used to tx parkinsons
-> parkinson’s shows less dopamine in substantia nigra and with it unbalanced high levels of ACh → these drugs can balance out the effects of ACh to what dopamine can do on basal ganglia
- MOA: Antimuscarinic agents used to tx parkinsons
- Improve tremor and rigidity of Parkinson’s but no effect on bradykinesia
- Memory issues
suffix of local anesthetics
-caine
How do you differentiate from name of drug if local anesthetic is amide or ester?
- amides have to i’s in the name like lidocaine, mepivacaine, etc
- esters have only one i like procaine, cocaine, tetracaine
What is the mechanism of action of local anesthetics? (3)
- local anesthetics are weak bases so in their uncharged form it can cross the cell membrane
- Inside the cell it binds to H+ to become charged
- Charged form is able to blocking OPEN STATE voltage gated Na+ channels - prevents depolarization to occur
Side effects of local anesthetics are uncommon but some can appear such as in…
1. CNS
2. Cardiovascular
3. Neurons/neurology
4. Blood
describe each side effect
- Initially cause stimulation (talkative, anxiety) and later can cause drowsiness
- Hypotension, arrhythmia, bradycardia, heart block
- Nerve injury if directly injecting drug into nerve
- amount of oxygen carried through blood is greatly reduced (hemoglobin can carry oxygen but is not able to release it effectively)
Cardiovascular side effects of local anesthetics usually are hypotension, bradycardia, and heart block but how is cocaine an exception to this?
- cocaine leads to hypertension and vasoconstriction
What local anesthetics cause methemoglobinemia (where hemoglobin is not able to release oxygen effectively)?
- prilocaine and benzocaine
Propofol
1. What type of drug?
2. MOA
- IV anesthetic
- Potentiate chloride current through the GABA-A receptor complex
- What effect does propofol have on anesthesia?
- What side effects can occur?
- induction and maintenance of anesthesia
- profound vasodilation -> hypotension
Etomidate
1. What type of drug?
2. MOA?
3. Benefit of this drug?
- IV anesthetic
- Potentiate Cl current through GABA-A receptor complex
- Preserves cardiovascular stability
Ketamine
1. What type of drug?
2. MOA
- IV anesthetic
- Inhibits NMDA receptor complex (which is usually activated by excitatory glutamate)
Affects on anesthesia by etomidate drug?
- for induction of anesthesia
- Affects on anesthesia by ketamine?
- Side effects?
- induction of anesthesia
- Dissociative anesthesia (eyes open with nystagmic gaze), unpleasant hallucinations, CV stimulation
When is benzodiazepines used as anesthetic?
- for conscious sedation for minor procedures (like colonoscopy)
- When is barbiturates used as anesthetic?
- What barbiturate is fast acting
- used for induction of anesthesia
- Thiopental - 5 to 10 minutes
Nitrous oxide
1. What kind of drug is this
2. pharamacokinetics in blood? (solubility in blood, onset of action, rate of recovery)
- inhaled anesthetic (laughing gas)
- less soluble in blood means gas will saturate the blood faster and partition into tissue -> faster onset of action.
- faster rate of recovery
Halothane
1. what kind of drug is this
2. pharamacokinetics in blood? (solubility in blood, onset of action, rate of recovery)
- inhaled anesthetic
- highly soluble in blood so slower onset of action and longer recovery
What does MAC mean for inhaled anesthetics?
the dose of anesthetic that causes 50% of patients to become unresponsive to painful stimuli
How can you determine potency of an inhaled anesthetic with MAC?
1/MAC
What are some side effects of inhaled anesthetics?
1. cardiovascular
2. pulmonary
3. blood
4. liver
5. kidney
6. muscle
- myocardial depression
- respiratory depression
- increased cerebral blood flow that can increase ICP
- Halothane can cause hepatotoxicity
- Enflurane can cause nephrotoxicity and seizures
- malignant hyperthermia
- What is malignant hyperthermia
- What can help treat this?
Can be a side effect of inhaled anesthetics
- Defective RyR releases excessive Ca2+ when introduced to anesthetic → leads to excessive ATP uptake by SR ⇒ lots of heat production (hyperthermia)
- This induces muscle damage (rhabdomyolysis)
- Dantrolene (muscle relaxant)
succinylcholine can also cause this side effect
Amyotraphic Lateral Scleroris (ALS) - Lou Gherig’s Disease
1. Pathophysiology
2. Does it show UMN or LMN sx?
- neurodegenerative disease - progressive degeneration of nerve cells of spinal cord and brain.
- Both - UMN (corticobulbar/corticospinal) and LMN (medullary and spinal cord) degeneration. No sensory or
bowel/bladder deicits.
-> LMN deicits: laccid limb weakness, fasciculations,
atrophy, bulbar palsy (dysarthria, dysphagia,
tongue atrophy).
-> UMN deficits: spastic limb
weakness, hyperrelexia, clonus, pseudobulbar palsy
(dysarthria, dysphagia, emotional lability).
ALS
1. what sx ultimately leads to death?
2. what tx is given for ALS?
- respiratory failure
- riluzole - not a cure but may extend survival
NMJ - where motor neuron meets what?
- meets a muscle fiber and causes muscle contraction
Myasthenia Gravis
1. pathophysiology
2. sx
- autoimmune condition- antibodies against post synaptic ACh receptors
- Fatigable muscle weakness—ptosis; diplopia; proximal weakness; respiratory muscle involvement; dyspnea; bulbar muscle involvement, dysphagia, dificulty chewing
Lambert-Eaton Myasthenia Syndrome (LEMS)
1. Pathophsyiology
2. Sx
3. Appears with what other disease
- Antibodies against calcium channels in the presynaptic membrane to decrease ACh release (this is more rare than myasthenia gravis)
- Slow onset with symmetric proximal muscle weakness + Autonomic symptoms (dry mouth, constipation, impotence) + Hyporelexia (decreased or absent reflex response) Improves with muscle use
- Paraneoplastic syndrome that classically occurs in small cell lung cancer
What sx presentation differentiates LEMS from myasthenia gravis?
- LEMS - muscle use will improve symptoms