Week 3 Flashcards
(127 cards)
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