Ch 27: Skeletal Muscle Relaxants Flashcards
neuromuscular blockers
can get muscle relaxation w/out deep depression
effects of neuromuscular blockers
- 1st cause muscle weakness, then flaccid & unexcitable
- larger muscles more resistant & recover quicker (diaphragm last)
act as:
depolarizing agents
non-depolarizing agents
depolarizing agents
- can cause arrhythmia (stimulates mus. & Nic receptors of heart… decrease inotropicity & chronotropicity)
- Succinylchlorine: paralysis takes 1 minute
non-depolarizing agents
- can cause hypotension (hist. release; give w/ antihistamine)
- Vecuronium, doxacurium
Spasmolytics
can reduce spasticity & spasms
Spasticity
abnormal stretch reflex, especially. w/ rapid lengthening of muscle: appears mostly due to “higher centers” (upper motor neuron lesion)
Spasms
afferents from damaged muscle tissue excites outflow from alpha motor neurons
Centrally acting agents
Diazepam
Baclofen
Tizanidine
Direct acting agents
Dantrolene sodium (Dantrium) Botulinum toxin (botox)
Diazepam
facilitates GABA-a activity
- causes sedation (problem)
- useful w/ spasms/spasticity (acts in the cord)
- causes sedation, hangover, tolerance
Baclofen
primary agent for spasticity
(beta-chlorophenyl- GABA)
- activates GABA in cord & increases K+ conductance (hyperpolarization)
- inhibits alpha motor activity
- given orally or intrathecal to subarachnoid space near affected area (can have problems w/ delivery system {pump, catheter} & tolerance)
Side effects of Baclofen
initial drowiness
fatigue
headache
Tizanidine
alpha 2 adrenergic agonist
- reinforce pre- and post-synaptic inhibition in cord
side effects of Tizanidine
drowsiness
hypotension
dry mouth
(studies show equal efficacy as diazepam, baclofen & dantrolene in several types of spasticity)
Dantrolene sodium (Dantrium)
primary use for MS
- inhibits calcium release from SR in “excited” muscle cells
- block receptor site on SR that opens the channels that calcium exits (ryanodine site)
side effects of Dantrolene sodium (Dantrium)
generalized muscle weakness
drowsiness
dizziness
- severe hepatotoxicity
Botulinum Toxin (Botox)
- binds ACh- containing vesicles and prevents exocytosis
can be injected into muscles
(takes days- weeks to elicit effect, last 2-3 months) - for spasmodic torticollis
laryngeal dystonia
Gabapentin
used in conjunction with other meds
- GABA-mediated inhibition of alpha motor n.
Opioid Analgesics
“without pain” (pain relief)
- sometimes called narcotic analgesics or narcotics
morphine
was once known to be a analgesic
- comes from a poppy seed after flowers fall off
(white latex, which is sticky and thick) is the “crude” opium
opioid receptor types
Mu
delta
kappa
(agonists of these receptors either block Ca2+ entry presynaptically {no transmitter release} or increase K+ conductance {hyper polarize cells})
Mu
analgesis
respiratory depression
dependence
Delta
analgesia at spinal level
kappa
analgesia at spinal level
Effects of opioid agonists
analgesia euphoria sedation respiratory depression cough suppression miosis trunk rigidity reduce GI motility rate
analgesia
reduce pain in sensory and affective (emotional) components
euphoria
pleasant, floating sensation
(free from anxiety & distress)
- can give dysphoria during/when stop taking
** can bring addicts back
sedation
drowsiness
cough suppression
reduce activity at cough “centers”
miosis
pupil constriction (seen in addicts; no tolerance to this)
trunk rigidity
increase tone of large trunk muscles
can block w/ neurons muscle blockers
reduce GI motility rate
can be constipating/ used to reduce severe diarrhea
Uses for opioid analgesics
analgesia
(use of morphine and others to reduce pain)
acute pulmonary edema
(slow breathing & shortness of perception of shortness of breath & anxiety)
cough
(use of dextramethorphan)
diarrhea
(slows GI motility .. esp. Loperamide)
pre-anesthesia
(sedating, anxiolytic, analgesic)
opioid side effects
tolerance
physical dependence
psychological dependence
tolerance
” need higher doses”
esp. analgesic, euphoric, and resp. depression
physical dependence
“rebound” effect opposite to acute administ
- hyperventilation, diarrhea, anxiety, hostility
psychological dependence
“NEED” to take to reserve disphorea
opioid agents
agonists
antagonists
agonists
- strong agonist
(morphine, methadone, fentanyl, levorphanol. For severe pain) –> act as mu and kappa - mild/mod agonist
codeine, hydrocodone, oxycodone, loperamide (lower efficacy at mu and kappa) - mixed agonist/antagonist
butorphanol, pentazocine
adequate analgesia, less tolerance and dependence, less resp depression and O.D. Activate kappa and sigma, block mu
antagonists
naloxone
naltrexone (for O.D.)
