Pharm Flashcards
How does DA affect the basal ganglia pathways?
activates direct pathway by binding to D1 receptors in striatum
inhibits indirect pathway by binding D2 receptors in striatum
What is the major degeneration in Huntington’s?
GABAergic inhibitory neurons –> hyperkinetic
What percentage of nigrostriatal dopaminergic neurons are lost before the symptoms of PD? What does this mean for drugs?
70-80%, most antipsychotics fxn when 70% D2 receptors blocked –> why they cause Parkinson symptoms
What is the difference between acute pain and chronic pain?
acute - from tissue trauma and inflammation, serves protective role, gone when injury heals = adaptive because promotes healing by restricting use of damaged areas
chronic - >3-6 mos, maladaptive
How is neuropathic pain different than nociceptive?
from direct injury to nerves, not activation of nociceptors
What are some important features of nociceptive pain and how it is managed?
somatic easy to localize, visceral is harder
tissue injury usually apparent
opiates most often relieve but may need adjuvants
When are adjuvant meds most helpful?
neuropathic, bone, smooth muscle, or skeletal muscle pain
increased ICP pain
when pt drowsy but still in pain!
How is neuropathic pain generally managed?
relieved somewhat with opiates, often needs adjuvants
What are characteristics of bone pain?
pain in bony tissue, achy, deep
worse with movement
often well localized
What kinds of meds are used to treat bone pain?
NSAIDs, Cox2 inhibitors steroids radiation therapy calcitonin bisphosphonates opiates radiopharmaceuticals
What are characteristics of smooth muscle spasm pain?
intermittent, severe, sporadic, come and go pain
worsens with opiates
What kinds of meds are used to treat smooth muscle spasm pain?
anticholinergic/antispasmotic agents: hyoscyamine, dicyclomine, atropine, scopolamine
What are characteristics of skeletal muscle spasm pain?
voluntary muscle injury or neurons misfiring
worse w movement/change of position
pts may assume unusual postures to relieve
What kinds of meds are used to treat skeletal muscle spasm pain?
physical measures - ice, heat, etc.
meds = muscle relaxants = baclofen, benzodiazepenes, methocarbamol, cyclobenzaprine
How is increased ICP pain treated?
steroids = dexamethasone, methylprednisolone
consider seizure prophylaxis
What is the WHO pain ladder?
step 1: mild pain - non-opiates (acetaminophen/NSAIDs/aspirin), maybe adjuvants
step 2: moderate pain - opiate/acetaminophen combo drugs, maybe adjuvants, ceiling dose 4 g tyl/day, consider tramodol or vicoprofen
step 3: severe pain - opiates, but demerol not recommended
What is one visceral pain that actually improves w anti-inflammatory treatment?
capsular stretch pain - stretching of liver capsule due to tumor,cirrhosis, or hepatomegaly
How are equianalgesic doses used to switch between analgesics?
start new med at 50-75% of equianalgesic dose and go from there
What are some principles of dosing opiates?
individualize by gradually escalating dose
around-the-clock dosing for continuous or frequently recurring pain
PRN dosing should be available for breakthrough pain (rescue dosing)
How can you select long acting vs. short acting opioids?
if requiring meds every 4 hrs PRN, consider long acting
consider patient factors
When are IV/SQ options considered sooner in pain management?
losing oral route, high cost of med/day, pediatric compliance with po dosing
What are some important advantages/disadvantages of morphine, oxycodone, hydromorphone, fentanyl, methadone?
morphine: long acting is PR, no ceiling, easy to titrate, some stigma
oxy: more potent long acting but more euphoria, can’t give rectally
hydromorphone: when morphine is problem, safe in liver patients
fentanyl: less constipating, less stigma, hard to titrate, conversions vary, skin issues, cost issues
methadone: cheap, highly effective, long duration, more serious side effects - get EKG
How should rescue dosing be given?
breakthrough dosing should be 10-20% of total daily opiate equivalent
frequency if oral is every 1-2 hrs
frequency if IV is every 10-30 min
total amount of required breakthrough in 24 hrs divided by 2 and added to pt’s 12 hr opiate dose
What are the principles of opioid dose adjustment?
no ceiling of opioid except toxicity so doses can be large - watch for side effects
increase dose by 25-50% for mild-mod pain
increase dose by 50-100% for severe pain
increase rescue dose as baseline is increased
