Muscle Relaxants Flashcards
Skeletal muscle (peripheral) relaxant
Dantrolene
MOA of Dantrolene
interfere with release of calcium from the sarcoplasmic reticulum of muscle cell
Does not cross BBB
Drug of choice for malignant hypERthermia (hypermetabolic syndrome) or tetanus
Dantrolene
Hypermetabolic syndrome:
- Often Fatal (hyperthermia, hyperkalemia, cell death)
- genetically determined idiosyncratic drug reaction
- rhabdomyolysis, shock, MODS (multiple Organ Dysfunction Syndrome)
This drug has a risk of rhabdomyolysis due to massive sympathetic discharge
Dantrolene
Central acting (spinal cord) muscle relaxants (2 answers)
methocarbamol and guaifenesin
MOA of methocarbamol
- Selective blockade of nerve impulse transmission in the spinal cord
- CROSSES BBB
- chemically related to guaifenesin
Tx of acute inflammatory/traumatic conditions and reducing mm spasm in cats, dogs, and horses
Methocarbamol
Route of Administration for methocarbamol
Oral tabs/Injectible
Irritating if IM/SQ admin
Methocarbamol pharmacokinetics
- Rapid oral absorption
- Relatively short half life
- Decreased T1/2 when admin IV
T/F: Patients on methocarbamol do not require ventilation, as is often the case with more potent drugs like neuromuscular-blocking agents
TRUE
paralytics –> ex. atricurium
Clinical uses for methocarbamol
- IVDD (Intervert Disk Disease)
- Tetanus
- Functional urethral obstruction/urinary retention (less common)
- Intoxication
Side Effects/Precautions for Methocarbamol
- Sedation, salivation, weakness, lethargy, and ataxia
- caution using injectable form w/ renal dz
- Avoid extravasation & administer IV injection slowly
- Expensive
MoA of Guaifenesin
- Acts mainly by BLOCKING nerve impulse transmission in the spinal cord, brain stem, and subcortical areas of the brain
- Some sedative and analgesic effects
Pharmacokinetics of Guaifenesin
Rapid onset
short duration of action (10-20 minutes)
considered long acting if used as part of an anesthetic induction and intubation protocol
