Pharmacology for neuromuscular Flashcards
Neostigmine (Prostigmin) class
Cholinesterase inhibitor
Neostigmine (Prostigmin) MOA
Prevents degradation of acetylcholine by cholinesterase
Increases the amount of acetylcholine available to active receptors, thus increasing muscle strength
Improves impulse transmission at the neuromuscular junctions throughout the body
What is acetylcholinesterase?
Acetylcholinesterase is an enzyme that normally breaks down acetylcholine → Neostigmine binds to cholinesterase, taking it up the medication is broken down instead of acetylcholine
Neostigmine (Prostigmin) description
Therapeutic doses increase the force of muscle contraction. At toxic levels, the medication does the opposite and reduces the force of muscle contraction → cholinergic crises
Parasympathomimetic → acetylcholine is the primary neurotransmitter of the parasympathetic nervous system
Indications for neostigmine (Prostigmin)
Used as treatment for Myasthenia Gravis, reverses muscle relaxants
neostigmine (Prostigmin) therapeutic effect
Improved muscle strength
Additional info for neostigmine (Prostigmin)
Administered IV, IM, and Subcutaneous injection (poorly absorbed in the GI tract)
Does not cure Myasthenia Gravis but provides symptom relief
Lifelong use
Adverse effects of neostigmine (Prostigmin)
Excess acetylcholine → excessive salivation, increased gastric secretions, increased tone/ motility of GI tract, urinary urgency, bradycardia, and sweating, bronchial constriction
Toxic doses can cause accumulation of acetylcholine that leads to paralysis of respiratory muscles and worsened muscle weakness
Cholinergic Crises
SLUDGE and the Killer Bs:
S: salivation
L: lacrimation
U: urination
D: diaphoresis/ diarrhea
G: gastrointestinal cramping
E: emesis
B: bradycardia
B: bronchospasm
B: bronchorrhea
Contraindications and precautions for neostigmine (Prostigmin)
Hypersensitivity
Bowel obstruction
Bladder obstruction
Cardiac issues → bradycardia, arrhythmias
Asthma
Nursing considerations and assessment for neostigmine (Prostigmin)
Monitor patient for improvement → increased ability to swallow and open eyelids
Nursing considerations and assessment for neostigmine (Prostigmin)
Monitor patient for improvement → increased ability to swallow and open eyelids
Patient may need to adjust dosage based on activity level (situational)
Assess patient for signs of underdosage (difficulty swallowing, ptosis) and overmedicating (excessive salivation, sweating, bradycardia, urinary urgency, increased GI motility, bronchoconstriction)
Monitor for Myasthenic crisis (under medicating) → extreme muscle weakness and
Monitor for cholinergic crisis (over medicating) → extreme muscle weakness and eventual paralysis and respiratory failure
Reversal agent for excessive muscarinic stimulation (cholinergic crisis) is Atropine
Patient should wear a medic alert bracelet
Myasthenic crisis vs cholinergic crisis
The patient with myasthenia gravis is in suspected cholinergic crisis. Which medication do you anticipate the health care provider will order?
Anticholinergic (Atropine)
Levodopa MOA
Crosses the blood brain barrier and converts to dopamine once it reaches the brain → thus restoring a balance between acetylcholine and dopamine
Indications for levodopa
Parkinson’s disease
Therapeutic effect of levodopa
Reduction in symptom severity, improvement in carrying out ADL’s
Does not cure PD or delay disease progression
Additional info of levodopa
Administered orally
Therapeutic response can take several months
Most effective drug for PD
Effectiveness of Levodopa decreases over time (symptoms are usually well controlled in first 2 years of treatment and effectiveness declines)
A small fraction of medication reaches the brain when it is given alone, and for this reason, Levodopa is given in combination
Levodopa/ Carbidopa (Sinemet)
Carbidopa has no therapeutic effects on its own
When levodopa is taken on its own, only a small portion reaches the CNS → this requires high doses that lead to more side effects
Carbidopa delays the process of peripheral drug metabolism, allowing for more levodopa to enter the brain
Adverse effects of levodopa/ carbidopa (Sinemet)
Nausea and vomiting → due to activation of dopamine receptors in the chemoreceptor trigger zone of the medulla
Dyskinesias → can cause movement disorders; tics, head bobbing, grimacing, rapid involuntary jerking, writhing movements, etc
Postural hypotension
Psychosis → visual hallucinations, vivid dreams, paranoia
CNS effects → anxiety, agitation, memory loss, cognitive impairment, issues with impulse control
Other side effects → can darken sweat and urine
Precautions and contraindications of levodopa/ carbidopa (Sinemet)
Hypersensitivity
Nursing considerations of levodopa/ carbidopa (Sinemet)
On/ Off phenomenon
Wearing-off phenomenon
Patients should avoid high protein meals → compete for absorption in gut
Assess for parkinsonian and extrapyramidal symptoms before and during therapy (shuffling gait, bradykinesia, drooling, pill rolling, tremors, twisting motions, masked face, rigidity)
Monitor blood pressure frequently during therapy
Patient should not transfer to a standing position abruptly
pramipexole (Mirapex) classification
Nonergot dopamine receptor agonist
pramipexole (Mirapex) MOA
Stimulates dopamine receptors in the striatum
Therapeutic effect of pramipexole (Mirapex)
Improve ability to carry out ADL’s → improvement in motor symptoms
Does not cure PD or delay progression of disease
Additional info of pramipexole (Mirapex)
Used on its own in early PD
Used in combination with other Parkinson’s drugs in advanced PD
Effects take several weeks to develop
Given orally
Adverse effects of pramipexole (Mirapex)
Associated with activating dopamine receptors → nausea, dizziness, sleepiness, confusion, hallucinations
When taken on its own, patients do not experience dyskinesias (abnormal movements)
When taken in combination with levodopa, the risk of developing orthostatic hypotension, hallucinations, and dyskinesias increases
“Sleep attacks” are overwhelming and irresistible sleepiness that come on without warning → ++ dangerous
Impulse control disorders → compulsive gambling, shopping, binge eating, hypersexuality
Nursing considerations & assessment of pramipexole (Mirapex)
Patients should be warned about potential to develop drowsiness → patients should not take sedating medications or alcohol while on pramipexole and should be asked about existing sleep disorders
Patients recently started on pramipexole should avoid driving or engaging in dangerous activities until they know whether it affects their wakefulness
If patient experiences sleep attacks, the medication should be discontinued
Monitor blood pressure regularly → advise patient to change positions slowly